Abstracts of PhD, MSc, MPhil and Diplome ingenieur theses in agroforestry, 1987-1998

compiled by August B Temu, Jimmy Kiio, Marie Kimenye and Eunice Gimode

Training and Education Report No. 42

©1998 International Centre for Research in Agroforestry PO Box 30677 Nairobi, Kenya

Correct citation: Temu AB, Kiio J, Kimenye M, Gimode E. comps. 1998.

Abstracts of PhD, MSc, MPhil, and Diplome ingenieur theses in agroforestry, 1987-1998. Training and Education Report No. 42. Nairobi: ICRAF.

Printed by Industrial Printing Works PO Box 58059, Nairobi

Contents

CONTENTS iii Preface v

THESES SUBMITTED FOR THE DEGREE OF DOCTOR OF PHILOSOPHY (PHD) 1

Effects of agroforestry practice on growth of teak, crop production, and soil fertility 1 Mulch quality and nitrogen dynamics in an alley cropping system in the Peruvian Amazon 2 The impact of capital land labour availability on smallholder tree growing in Kenya 2 Human disturbances and vegetation dynamics in the Narok District of Kenya 3 Soil fertility and productivity aspects of alley cropping Leucaena leucocephala and Cassia siamea under semi-arid conditions at Machakos, Kenya 4 An investigation of the characteristics of drought tolerance for two varieties of Sesbania sesban (L.) Merrill, applications for the selection and improvement of multipurpose agroforestry species 5 Genetic assessment of perennial Sesbania species in agroforestry systems 6 Reproductive biology of Irvingia gabonensis (O'Rorke) Baill. in southern Nigeria: phenology, floral biology and varietal characteristics 7 The adoption of alley farming in Nigeria and Benin: the on-farm experience of IITA and ILCA 8 Investigation of athropods associated with agroforestry in Machakos, Kenya 9 Multipurpose tree primings as a source of nitrogen to maize (Zea mays L.) under semi-arid conditions in Zimbabwe 10 Limits to predictability: on-farm spatial and temporal variability and the design of on-farm agroforestry trials 11 Issues in the utilisation of indigenous knowledge in agroforestry research 11 Ecology and management of Uapaca kirkiana in southern Africa 13 The anatomy of innovation adoption: the case of successful agroforestry in East Africa 14 Species selection for alley cropping in western Kenya: system management, nutrient use efficiency and tree-crop compatibility (1988-1995) 15 Assessment and prediction of wood yield from agroforestry systems in Kenya 17 The diffusion of social forestry in semi-arid areas: a case study of Kitui District, Kenya 18 Tree-biomass decomposition, nitrogen dynamics, and maize growth under agroforestry conditions in the subhumid highlands of Kenya 19 Influence de Cordyla pinnata sur la fertilite d'un sol ferrugineux tropical et sur le mil et l'arachide dans un systeme agroforestier traditionnel au Senegal 20 Germination du palmier doum (Hyphaene thebaica Mart.) et analyse de son interaction avec le mil (Pennisetum glaucum L.) en zone semi-aride du Niger 20 Management of Calliandra calothyrsus in association with Pennisetum purpureum for increased dry season forage production on smallholder dairy farms in central Kenya 21

THESES SUBMITTED FOR THE DEGREE OF MASTER OF SCIENCE (MSC) AND MASTER OF PHILOSOPHY (MPHIL) 23

Biomass, volume and nutrient accumulation by six-year old Acacia albida under agroforestry at Mafiga, Morogoro, Tanzania 23 A study of alley cropping maize and green gram with Leucaena leucocephala (Lam.) De Wit at Mtwapa, Coast Province, Kenya 24 Plant nutrient aspects of mulch incorporation in alley cropping trials of semiarid Machakos, Kenya 25 Acacia, leucaena and sesbania green manures affect maize growth in the Tabora region of Tanzania 25

Inorganic and organic phosphorus transformations during 18 years of cultivation in the Amazon Basin 26 Decomposition of leaves from N-fixing trees in Zambian agroforestry 27 Effect of pruning frequency on the yield of maize/cowpea in a Leucaena alley cropping system 27 Evaluation of the nutritive value of some selected multipurpose trees and shrubs (MPTS) 28 The potential use of contour hedgerows for soil erosion control in the highlands of Kabale District, southwestern Uganda 30 Water and crop biomass dynamics in a Cassia siamea Lam. and Zea mays L. alley-cropping systems 30 Identification and characterization of browse plants in Kumasi District, Ashanti Region of Ghana 31 Decomposition and nutrient release patterns of leaf mulches of Leucaena leucocephala, Gliricidia sepium and Cassia spectabilis 32 The effect of season and shrub-grass combination of the fodder quality of three agroforestry plant species grown in Maseno, western Kenya 33 A preliminary quantitative survey of the insect-pest complex of some leguminous multipurpose trees in southern Nigeria 34 Identification of constraints and analysis of agroforestry interventions for improved livestock production of the Ejura livestock project and its environs (Ghana) 34 Effect of slash-and-burn practice and Leucaena leucocephala residue management on nutrient dynamics in the humid lowlands of Ghana 36 Evaluation of the potential of rotational tree fallows for sustaining maize production at Meatu, Shinyanga, Tanzania 37 Evaluation of the effect of hedgerow intercropping using Leucaena leucocephala and fertilizer application on growth and yield of garden eggs (Solanum melongena) 38 Urban home gardens in Kumasi metropolis, Ashanti Region of Ghana 39 Leucaena leucocephala and Gliricidia sepium supplementation of growing sheep fed rice straw: effects on feed intake, liveweight gain digestibility and rumen degradation characteristics 40 The influence of socioeconomic factors on the promotion and adoption of agroforestry technologies based on the traditional ngitiri system 41 Influence of some multipurpose tree species on soil fertility 42 Evaluation of indigenous fodder trees and shrubs in different agro-ecological zones of western Kenya 43 Potential use of Calliandra calothyrsus hedges with napier grass (Vennisetum purpureum) for soil erosion control in a high potential area of Embu, Kenya 43 Agroforestry adoption by small-scale farmers: a case study of pioneer tobacco company's agroforestry programme 44 The effect of Leucaena leucocephala mulch on the growth and yield of irrigated tomato (Lycopersicon esculentus Mill.) 45 Rooting characteristics and inorganic nitrogen distribution in three land-use systems on an Oxisol in western Kenya 46 Women and agroforestry in Kabale District, Uganda: an exploratory study of social issues affecting women's agroforestry behaviours and production 47 Propagation of Uapaca kirkiana using tissue culture techniques 47 Constraints and solutions to small-scale tree nursery management in the coffee based land-use systems of Murang'a District, Central Highlands, Kenya 49 An assessment of traditional agroforestry systems in Arua District, Uganda 50 Evaluation of incentive packages to farmers for tree planting: a case study of Ashanti Region of Ghana 51 Adoption and farmer perception of agroforestry practices by low resource farmers — a case study of Malawi 52 Typologie et dynamique des peuplements arbores du bas-glacis de Bondoukuy, ouest du Burkina Faso 53 Evaluation of multipurpose shrub legumes for use as nitrogen supplements in maize stover based diets for growing goats 54 Control of nitrogen mineralization from decomposing Gliricidia sepium leaves to optimize nitrogen uptake by maize crop 55 Factors contributing woodfuel scarcity and the consequent use of crop residues for domestic energy in rural Kenya 56

iv

Forest resource management for sustainable development: a case of Mount Meru Forest Reserve in northern Tanzania 57 Inventory of indigenous agroforestry systems in practice in the West Usambaras 58 Effect of Leucaena leucocephala biomass and sawdust on physical and chemical properties of the soil and on growth and yield of soyabean (Glycine max) 59 Propagation of Parinari curatellifolia Planch ex Benth. and Uapaca kirkiana Muell. Arg. by seeds and stem cuttings 59 Evaluation of pods from three acacia trees and leaves of Terminalia brownii and Berchemia discolor as dietary supplements for growing goats 60 An evaluation of tree/shrub species and provenances for fodder production, Embu, Kenya 61 Intake and digestibility of low quality rhodes grass hay and growth of sheep as affected by browse supplement and Magadi treatment 62 Tree planting under customary land and tree tenure systems in Malawi: an investigation into the importance of marriage and inheritance patterns 63 Analysis of some socio-economic factors that affect the adoption of agroforestry technologies in the Yensi Valley in Akwapim, Ghana 64

THESES SUBMITTED FOR DIPLOME (INGENIEUR AGRONOME) AND DIPLOME (INGENIEUR DES EAUX ET FORETS) 65

Possibilite d'utilisation d'arbustes comme source d'engrais vert dans la production du sorgho a Samanko 65 Disponibilite fourragere et commercialisation de fourrages ligneux sur les marches de Bamako 65 Possibilite d'utilisation d'arbustes comme source d'engrais vert dans la zone de Samanko : capacite fertilisante et perspectives agroforestieres 66 Commercialisation des produits forestiers non-ligneux sur les marches de Fana 67 Evaluation de provenances de Gliricidia sepium : perspectives agroforestieres de l'espece pour la production fourragere dans la zone semi-aride au Mali 67

INDIVIDUAL TRAINING OF SCIENTISTS AT ICRAF 69

ANNEX 1. SAMPLE APPLICATION FORM 73

V

Preface

The contribution of graduate students to the growth of science is well acknowledged in all disciplines. Through their thesis research, graduate students also facilitate links between universities and research institutions. ICRAF makes special efforts to provide opportunities for graduate students to undertake their thesis research in agroforestry at over 30 collaborative research sites managed by ICRAF and its partners in Africa, Southeast Asia, and Latin America. For us, thesis research students have made and continue to make a significant contribution to the science in agroforestry, particularly during the last ten years. Their work also underpins the incorporation of agroforestry education at universities and promotes collaboration between universities and ICRAF. All these are highly desirable outcomes.

In this publication, we present a compilation of PhD, MSc, MPhil and Diplome ingenieur theses in agroforestry currently available at ICRAF. They have been presented in the original languages used for the theses. Our aim is to share this information with the global scientific community. We believe that this publication will attract more students to undertake thesis research with ICRAF and its partners. Most importantly, this publication highlights the emerging science of agroforestry as an important field of academic study.

Over the last five years, we have experienced a rapid growth in the numbers of graduate students wishing to undertake thesis research at ICRAF. We have therefore included at the end of this publication some information on opportunities for thesis research at ICRAF. Additionally, every two years ICRAF publishes a list of thesis research opportunities, intended to attract students from all over the world. Interested students and universities may request copies.

Dr Glenn Denning Director, Development Division ICRAF

vi

Theses submitted for the degree of Doctor of Philosophy

(PhD)

Effects of agroforestry practice on growth of teak, crop production, and soil fertility

Mohamad Sambas Sabarnurdin, PhD, 1988

Supervisors: Dr Donald I Dickmann Dr James W Hanover Dr Lawrence O Copeland Dr Michael A Gold Dr PhuV Nguyen

University: Michigan State University, USA

Abstract To investigate the ecology of the tumpangsari agroforestry system as practised in Java, teak (Tectona grandis L.) was grown in the Wanagama I forest area 36 km south of Yogyakarta, Indonesia, in combination with rice (Oryza sativa L.), corn (Zea mays L.) and peanut (Arachis hypogea L.) in plots with or without a legume (Acacia villosa L.).

Teak grown with rice or peanut performed better than when grown with corn or without crop. With the exception of the teak-rice combination 16 months after planting, Ihe effect of acacia was found not significant. The type of crop significantly affected the performance of teak, although the difference between teak grown with rice and with peanut was not significant. The order of positive companionship of crops on teak was rice>peanut>com and peanut>rice>corn at four and 16 months respectively.

No significant reduction of crop yields was observed after the second cropping season. Acacia has shown a significant effect on crop yields on a row basis but not on a plot basis. Its distance from the teak was significantly affected by root occupancy of the teak-crop combination but not by the depth of the soil. Roots of the teak-rice combination occupied the soil more extensively than the other teak-crop combinations.

Nitrogen, P and organic carbon concentrations of the surface soil decreased significantly after four months, while those of the subsurface soils increased. The effect of acacia on soil N was not significant. There were no significant effects on soil total exchangeable bases for both surface and subsurface soils.The findings support the agrisilvicultural practice during forest establishment, and under the conditions of the experimental area, the suggested cropping sequence for tumpangsari is rice-peanut-corn.

PhD theses

Mulch quality and nitrogen dynamics in an alley cropping system in the Peruvian Amazon

Cheryi Ann Palm, PhD, 1988

Supervisors: Pedro Sanchez (ICRAF) Dr SW Duol Dr M Davidian

University: State University of North Carolina, Raleigh, USA

Abstract Alley cropping has potential to sustain crop production in the tropics because of N supplied to crops from prunings of N-fixing legumes. Results from some alley cropping experiments are promising but N utilization efficiency are low. A reason given for the low efficiency is possible asynchrony between supply and demand of N. Efficiency could perhaps be improved if release of N was synchronized to crop demand, either by timing of application or by using mulches with differing N release patterns. A study to address these questions was conducted over a two-year period in the Peruvian Amazon. There were three main objectives: (1) to determine whether leaves of leguminous plants differed in their N release patterns, and if so what factors are controlling N release, (2) to determine the effect of leguminous mulches of differing quality of soil C and N dynamics; and (3) to determine the effect of mulches of differing quality on crop yields and N utilization efficiency.

Results of a laboratory experiment in which N release patterns were determined for ten tropical legumes showed that legumes do differ in quality. Nitrogen release patterns were negatively correlated to polyphenolics in the leaves but were not correlated to N or lignin. Polyphenolics may form stable complexes with amine or nitrate N, making N unavailable to microbes.

A field experiment addressed the second and third objectives. Prunings from three leguminous trees, Inga edulis, Cajanus cajan and Erythrina sp were applied as mulch at rates of 0, 3.3 and 6.7 t dry matter/ha to four consecutive crops of upland rice. Soil and light fraction C and N did not differ among treatments at 22 months. Mineralization patterns and microbial N did differ. Erythrina, the mulch of highest quality, generally had higher values. Yields of rice did not differ among the mulches despite differences in mulch quality, N mineralization, and soil microbial N. Yields did increase with mulch rates. Nitrogen utilization efficiency was in general quite low (15%). The N losses could be due to volatilization or leaching resulting from asynchrony of N supply and demand.

The impact of capital land labour availability on smallholder tree growing in Kenya

Peter Allen Dewees, PhD, 1991

Supervisors: Mike Arnold Paul Collier

University: University of Oxford, UK

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PhD theses

Abstract Smallholder tree cultivation and management is a common form of land use in high potential areas of Kenya. Some practices, such as the planting of trees on field boundaries, are strongly tied to customary notions of land and tree tenure. Others, such as the planting of black wattle (Acacia mearnsii) woodlots, are more recent innovations, introduced to produce commodities for domestic and export markets. This thesis explores the historic, cultural, and economic dimensions of tree growing in Kenya, using archival and ethnographic data, land-use surveys and results from a survey of 123 households in the upper coffee/lower tea zone of Murang'a District.

The household survey was designed to explore the hypothesis that tree growing complements formal employment as a strategy for overcoming poorly operating factor markets and helps to ease land-use constraints imposed by labour migration. Tree planting is favoured because of its low capital and recurrent costs and when farmers are unable to plant other more resource-intensive crops. The survey focused on households which currently maintain a black wattle woodlot and on households which operate parcels which were used for growing black wattle in 1967, but which have since been cleared and are being used for growing something else.

The survey showed that woodlot growing households operate larger parcels, are older, support fewer residents, and have more non-resident relatives than other households in the survey. Woodlot growing parcels are also at a lower altitude and are more steeply sloping than other parcels. Patterns of resource allocation suggest that woodlot growing households are are less willing to take risks.

Logistic repression (logit) modelling explored casual relationships, suggesting woodlots are indeed more likely to be established as households age and as labour becomes scarce, and that woodlot clearance takes place when labour is more available to cultivate the holding.

Human disturbances and vegetation dynamics in the Narok District of Kenya

Zadoc A Ogutu, PhD, 1991

Supervisors: Dr Peter A Furley Miller Colins Dr A Young

University: University of Edinburgh, Scotland, UK

Abstract This thesis is an examination of human impact on plant species composition and vegetation structure of the Narok District, Kenya. This is achieved by comparing the vegetation on disturbed and undisturbed sites. A literature review confirms that vegetation changes are associated with seasonal migration of humans and animals, loss of land, firstly, to white highland development and, secondly, to cultivators immigrants and developments which hardly involve the local people. Analysis of satellite imagery provides synoptic evidence of rapid expansion of cultivation. Field sampling suggests that no disturbance type is uniformly distributed and that the disturbances are becoming increasingly permanent and predominantly large-scale due to increasing human population and changes in Maasai lifestyles.

Proximity factors, plant life form and human disturbance determine the description of vegetation data using indices of similarity suggests that samples association. Alpha diversity indices suggest that medium human disturbances increase species diversity while extreme disturbances reduce

PhD theses

species diversity through resource monopolization (for low disturbance) and through destruction of re-establishment potential (for high disturbance).

Plant structural differences are attributed to methods of wood harvesting, grazing intensity, browsing preferences, changes in fire regime and differences in moisture and soil nutrients. Examination of floristic and structural data suggests that high human disturbance reduces the number of woody species and the volume of wood while disturbances favour the predominance of woody species. In contrast, medium human disturbance attracts both succession and climax species. An inhibition model is suggested for the change in species composition at different height categories. This is either due to the exclusion of seedling recruitment by resource monopolization in undisturbed sites or to suppression of recruitment of plants to the next stage in highly disturbed sites.

PCO ordination of floristic data based on species association shows a sample pattern which firstly varies with moisture gradient, organic carbon, nitrogen and zinc, and secondly suggests the influence of human disturbance, mainly between disturbed and undisturbed forest and bushland sites. Classification of vegetation data using both average linkage and furthest neighbour algorithms produce clusters on the basis of sample closeness suggesting a continuous rather than a discrete distribution of species. Lack of earlier fusing of samples of the same disturbance characteristics and from the same plant community is attributed firstly to the relatively recent human influence which has had little affect on plant composition, and secondly to plant resilience to human impact on vegetation.

In view of the findings, different alternatives of manipulating extreme human disturbances for the management of vegetation are offered.

Soil fertility and productivity aspects of alley cropping Leucaena leucocephala and Cassia siamea under semi-arid conditions at Machakos, Kenya

Bashir Jama Ada, PhD, 1993

Supervisor: DrPKRNair

University: University of Florida, Gainesville, Florida, USA

Abstract Soil productivity aspects of alley cropping under semi-arid conditions were investigated in a three-year study at Machakos, Kenya. The aims were (1) to determine if alley cropping with leguminous trees and shrubs improves soil fertility and productivity, (2) to separate the effects of mulch per se from those of in situ presence of the hedges, (3) to assess the extent of tree-crop interaction patterns, and (4) to determine the major factors that influence farmers' adoption of alley cropping. The study consisted of Leucaena leucocephala and Cassia siamea alley cropped with maize (Zea mays); the woody species were also grown in sole-stand blocks outside the cropped field, their primings applied as mulch to the cropped area in equivalent land areas.

Difference in maize yield between alley-cropped plots and the plots receiving mulch from the block plantings showed that growing the hedges in situ had a positive effect on maize yield. Yield advantage of alley cropping over the separate crop and hedge planting systems, expressed as land equivalent ratios, were 36% and 12% for cassia and leucaena respectively. Leucaena produced more biomass (4 t/ha/year) than cassia (2 t/ha/year); also leucaena had higher fine-root density than cassia in the topsoil (0-40 cm). Therefore, leucaena was more competitive than cassia, and

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PhD theses

over the years, maize yield declined by 12% under leucaena whereas it increased by 8% under cassia.

For both species, maize nearer the hedgerows yielded more than those away from them. Soil water content was also higher near the hedgerows. Chemical and physical properties of the topsoil (0-20 cm) did not differ significantly between treatments (with or without mulch or alley cropping) or over time for a given treatment. The quantities of mulch produced by the hedgerows were generally low; and they decomposed quickly (half-life of four weeks); these could be the main reasons for the lack of significant changes in soil properties.

Farmers were generally more interested in the fodder than die mulch aspects of alley cropping. Because of the initial high investments of inputs such as labour and seedlings required to establish the hedgerows, alley cropping is more likely to be adopted by relatively resource-rich farmers such as coffee growers than by poorer farmers.

An investigation of the characteristics of drought tolerance for two varieties of Sesbania sesban (L ) Merrill, applications for the selection and improvement of multipurpose agroforestry species

Nick Jackson, PhD (Agroforestry), 1993

Supervisors: Dr Howard Griffiths

Dr Mose Zeroni

University: University of Newcastle-upon-Tyne, UK

Abstract The relative drought tolerances of Sesbania sesban var. Nubica and var. Sesban under well-watered and water-stressed conditions were investigated, in terms of physiological and growth responses. Experiments were conducted using seedlings in a controlled environment growth chamber and outdoors in the Negev Desert, Israel. Field trials using both varieties were also conducted in the Negev. The Nubica variety showed greater biomass accumulation, higher growth rates and a greater proportional allocation of reserves towards below-ground biomass than the Sesban. The Sesban variety demonstrated a greater rate of leaf shedding under both water regimes than the Nubica, and a tendency to produce taller, thinner plants. In terms of physiological responses, the Nubica variety was able to maintain higher rates of CO2 uptake than the Sesban under acute soil-water deficits, a greater degree of stomatal control of photosynthesis in response to the onset of water stress, and higher values for the carbonxylation efficiency and apparent quantum yield. The Nubica plants exhibited greater control of plant-water status, through greater hydraulic efficiencies, and higher instantaneous and seasonal water-use efficiencies than the Sesban.

Considerable variation in drought tolerance was demonstrated between individuals within each variety, and this was shown to be largely genotypic in origin. The carbon isotope discrimination ( ) was negatively correlated with both instantaneous and seasonal water-use efficiencies, and was shown to be a good physiological indicator of drought tolerance characteristics, when used in conjunction with other variables such as the degree of canopy development, and the relative degree of soil-water deficit. The possibility of using A in the selection of the multipurpose tree species for use in arid-zone agroforestry systems is discussed. Measurements of stem height and basal diameter provided a useful allometric method for non-destructive estimation of biomass.

5

PhD theses

Genetic assessment of perennial Sesbania species in agroforestry systems

Peter Allan Oduol, PhD (Agroforestry), 1994

Supervisors: Dr DC Malcolm Dr Roger RB Leakey (ICRAF) Dr J McP Dic Dr Fred Owino (ICRAF)

University: University of Edinburgh, UK

Abstract The aim of the study was to establish whether clones could be selected for single or multipurpose products by conducting studies involving the evaluation of phenotypic characteristics and their influence on biomass production using Sesbania sesban (L.) provenances and clones.

The study initially examined the extent of genetic variation in phenotypic characteristics and biomass production in 5. sesban provenances at Maseno, in Kenya. The study showed that significant differences existed between provenances and that it was possible to select outstanding individual trees in the best provenances for testing on different sites and clones. Significant allometric relationships were established between dry mass, and tree dimensions for the different tree components. Stem diameter at 0.15 m provided a reliable estimation of biomass in the provenances. The provenance repeatabilities (0.31-0.41) and potential genetic gain (40%) highlight the expected returns due to selection.

Plant growth analysis results helped in understanding the growth of young S. sesban clones in the field at Maseno, particularly the distribution of biomass into components. Clones performed similarly in the initial stages of growth and differences were only detected when competition set in. Clone net assimilation ratios were found to be sensitive to moisture stress. Leaf area was found to be the major determinant of clonal differences and was a good indicator of plant growth and productivity.

The results from the genetic variation and productivity study of S. sesban clones grown at Maseno, Kisii and Machakos revealed a differential response of the clones to different environmental conditions. There was genotype by environment interaction in clone heights, biomass production was higher at Maseno and Kisii than Machakos. S. sesban clones differed greatly in absolute biomass but showed similar percentage distribution of dry mass among the different tree components with branches being a major preferred sink. Stem diameter at 0.15 m was more reliable in predicting biomass for the clone components (R2 = 0.65-0.74). Different crown forms in S. sesban clones were due to differences in branch lengths and angles. The broad sense-heritabilities of these traits indicate that the genetic components of variance were large enough to permit effective selection for stem diameter, leaf area and crown form.

The results of the predictive test study showed mat it is possible to use juvenile physiological selection criteria for genotypes bud activity following decapitation to improve selection criteria for genotypes with desirable morphological attributes. The results from the light interception and stomatal conductance study established that S. sesban clones which captured the most light, regulated water loss and were most productive.

The study demonstrated that it is possible to select and develop highly productive single-purpose clones for some sites, and it is possible to combine into a single cline, superiority for a product

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PhD theses

and an environmental service. The results highlight the potential use of both morphological and physiological criteria for selecting clones of S. sesban of high productivity for agroforestry.

Reproductive biology of Irvingia gabonensis (O'Rorke) Baill. in southern Nigeria: phenology, floral biology and varietal characteristics

Gloria Chinwe Ujor, PhD, 1994

Supervisors: David Okali

Dr David Ladipo (ICRAF)

University: University of Ibadan, Nigeria

Abstract Irvingia gabonensis (O'Rorke) Baill. is an important indigenous fruit tree in west Africa. The fruit mesocarp is eaten fresh and the cotyledon is used as a soup condiment. It has recently become a major commodity of commerce in Nigeria and West Africa in general (Agbor 1986). In spite of its importance, very little is known about the reproductive biology of the species. To remedy this, the phenology, floral biology, pollination and varietal characteristics of I. gabonensis in Ibadan (Oyo State), Enugu (Enugu State), Sapoba (Edo State), Ikom (Cross River State) and Onne (Rivers State) were studied. Phenological observations were made of onset and duration of flowering and fruiting. The intensity of flowering was estimated and the sequence of anthesis in the inflorescence was observed. An attempt was made to provide a model for predicting flowering and major climatic factors (rainfall, temperature and relative humidity) through regression analysis. Floral biology of the species was investigated by examining flower structure, fruit development and characteristics, pollination, reproductive efficiency, pollen viability and pollinators. Morphological responses of I. gabonensis seedlings to plant growth regulators, which are known to induce flowering were tested.

An attempt was made to investigate potential field performance of varieties or land races of the species through the study of juvenile characteristics. Pollination was investigated through bagging experiments and observations on pollinators of the flowers. Reproductive efficiency was assessed using the relation between fruit production and flower density. Regression models also investigated the relationship between fruit production and other floral parameters.

/. gabonensis was observed to flower virtually all year round but flowering was mainly in the drier months of October to February. The peak flowering period is January to March for the var. gabonensis and September to November for the var. excelsa. The period of flowering among the locations varies slightly. In the two years of observation, the duration of flowering varied from 22 to 80 days in all the sites while the duration of fruiting varied only between 97 and 114 days. Onset of flowering in the varieties and the species could be predicted using the following models: Y(ex) = 89.9023 - 0.0168V, - 0.1358V2 - 2.4367V3

Y(ga)= -317.057 - 0.1114V, + 1.9422V2 + 7.0525V3

Y(sp) = 91.904 - 0.0022V, + 0.25389V2 + 3.92143V3

where Y(ex), Y (ga) and Y(sp) are the dependent variables (flowering onset for var. excelsa, var gabonensis and the species respectively) and V1, V2, V3 are the independent variables rainfall, relative humidity and temperature, respectively.

The inflorescence of I. gabonensis is made up of single pedicelled and complete flowers occurring in clusters. Although the family is characterized by five sepals, five petals and nine stamens, it is

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PhD theses

not uncommon to see flowers with four and six sepals, four and six petals and stamen number of eight, ten, eleven and twelve.

Pollen of I. gabonensis varies in size from 19.6 microns to 24.3 microns. The pollen remain viable after seven days of storage in a medium of 0.1% Boric acid + 20% sucrose. Controlled pollination experiments show that I. gabonensis is both self-compatible and outcrossing. In observations made at Enugu and Ibadan, thirty-nine insect species belonging to eight orders were seen to visit the species during floral blooming. Mean fruiting efficiency for the species was 37.37%.

Plant growth regulators (Cultar, Alar, Cycocel and NAA) tested did not induce flowering in the species. However, significant differences were found on their effect on the vegetative growth of the species. The effect was more pronounced in var. excelsa. Crown colour changes were observed in var. gabonensis. There was a greater tendency for polyembryony to occur in var. gabonensis than in var. excelsa. No differences in land races or provenances were found in germination and early seedling growth.

While further work will be needed to clarify chromosome and flower induction characteristics in /. gabonensis, particularly for the purpose of developing breeding strategies, the present study provides useful information on the phenology, floral biology and varietal characteristics of the species. This information can contribute to the development of I. gabonensis as an agroforestry species for Nigeria. Such planting, by increasing vegetative cover while providing food, can help to ameliorate both the land degradation and food security problems that are well pronounced in southern Nigeria; the area of immense forest exploitation for timber and fuelwood.

The adoption of alley farming in Nigeria and Benin: the on-farm experience of IITA and ILCA

Michael PB Whittome, PhD, 1994

Supervisor: Tim Bayliss-Smith

University: University of Cambridge, UK

Abstract Alley farming is an agroforestry method in which food crops are grown in 'alleys' between rows of trees. Trees are regularly pruned to prevent them shading companion crops, and primings are used primarily as a mulch to restore soil fertility, but also to supply firewood, fodder, yam stakes and construction wood.

During the 1980s, alley farming caused considerable interest in the scientific community as a low-cost innovation capable of stabilizing the crop yields of resource poor farmers in tropical countries. With huge financial backing, many research centres carried out extensive on-station trials in an attempt to evaluate the agronomic potential of the technology and determine appropriate management practices.

The International Institute of Tropical Agriculture (IITA) and the Humid Zone Programme of the International Livestock Centre for Africa (ILCA), both located in Ibadan, Nigeria, were instrumental in raising awareness of the potential of the method. However, donor organizations are now concerned that the initial promising on-station results have not been matched by the rapid adoption of the method by farmers.

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PhD theses

This thesis reviews IITA's and ILCA's on-farm research with alley farming and attempts to understand the farmers' responses to the technology and provide guidelines for future extension projects. A comprehensive formal questionnaire with all the known alley farmers was combined with more informal rapid and participatory methods of data collection, and the data was cross­checked with IITA's and ILCA's available records.

The research has revealed that most of the farmers only cropped their alley fields for the first few years, after which the land was left fallow. IITA and ILCA have failed to introduce alley farming into areas to which the method is most suited and farmer participation was achieved through the provision of incentives such as free fertilizer, improved crop material and livestock vaccination.

Although IITA and ILCA are responsible for research and not extension, valuable lessons for extension organizations can be obtained by examining their work and analyzing the experiences of farmers who have so far had experience with alley farming.

Investigation of athropods associated with agroforestry in Machakos, Kenya

Martin Luther Opondo-Mbai, PhD (Biological Sciences), 1995

Supervisor: Dr Martin R Speight

University: University of Oxford, UK

Abstract A survey of arthropods associated with exotic multipurpose trees and food crops and in agroforestry and indigenous tree species was undertaken. The trees were Gliricidia sepium, Leucaena leucocephala and Cassia siamea growing in an alley cropping system and the food crops were Vigna unguiculata, Zea mays and Cajanns cajan. The consequences of growing taxonomically related plant species in agroforestry system were considered. Insecticidal knockdown technique was used to sample arthropods from the foliage. Ninety-two species of arthropods belonging to 48 families were found to be associated with the tree species and crops. Of these, 27 species were shared amongst multipurpose trees and crops while 14 species were shared between multipurpose trees and wild trees. A further 19 species were shared between all the groups of plant species (multipurpose trees, crops and wild trees) with four species being shared between wild trees and crops. The effect of tree pruning on arthropod communities on trees was also investigated. Results showed that pruned trees supported a richer arthropod fauna than unpruned trees.

Through simulated defoliation, the impact of insect defoliators on four multipurpose trees was also investigated. There was a considerable reduction in overall growth rate, height and diameter increment depending on the level of defoliation. Several stress factors often predispose plants to insect attack. Pruning as a stressing agent was investigated in relation to infestation of Cassia siamea by the stem borer Xyleutes capensis. Out of 200 pruned trees surveyed, 90% showed signs of borer attack, compared with only 31.5% of unpruned trees.

The role multipurpose trees can play in aggravating infestation of stored pulses by a bruchid beetle Callosruchus chinensis was investigated by comparing its survival on seeds of three multipurpose trees and Cajanus cajan. Whereas the bruchid was able to lay eggs on both the multipurpose trees and crop seeds, no larval emergence was observed in any of the multipurpose trees showing that the multipurpose trees may not support reproduction and development of C. chinensis in the field.

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PhD theses

Multipurpose tree prunings as a source of nitrogen to maize (Zea mays L.) under semi-arid conditions in Zimbabwe

Paramu Mafongoya, PhD, 1995

Supervisors: Dr PKR Nair Dr LE Sollenberger DrJH Conrad Dr Ben Dzowela (ICRAF) Dr J Reed Dr KE Giller

University: University of Florida, Gainesville, Florida, USA

Abstract Prunings of multipurpose trees are used in the tropics as a source of nitrogen to maize. However, research results have shown that nitrogen recovery from the prunings so used is generally low, the main reason being possible asynchrony between N supply by prunings and demand for N by the crop. Nitrogen recovery could possibly be improved if N release is synchronized to crop N demand either by modifying the method of timing or pruning application or by using prunings of different quality with varying N release patterns.

Nitrogen recovery of multipurpose tree prunings as a source of nitrogen to maize was studied in a series of field and pot experiments. Seven multipurpose tree species commonly found in agroforestry systems were used. The aims of the study were to (1) evaluate the effect of chemical composition of multipurpose tree prunings on their decomposition and N release patterns, and (2) study interactions of pruning quality, method and time of pruning application and soil type on nitrogen recovery by maize.

The nitrogen release patterns of various prunings were related to their chemical composition. Cumulative nitrogen released over time was correlated with % lignin, % NDF-N, polyphenol: N ratio, and (lignin + polyphenol) : N ratio. Nitrogen release patterns from multipurpose tree prunings can be predicted using polyphenol: N and (lignin + polyphenol) : N ratios as indices of chemical quality of prunings.

Incorporating prunings gave higher nitrogen uptake, nitrogen release and maize grain yield than surface application, for most of the species. Application of prunings at planting gave higher nitrogen release than application two or four weeks after planting maize. However, prunings applied four weeks after maize emergence resulted in higher nitrogen release by the subsequent crop man those applied at planting. This result was dependent on species, soil type and application method.

There was no difference in nitrogen release from splitting the application of prunings, half at planting and half two or four weeks later, compared to one-time application at either time. Mixing of prunings of different multipurpose tree species did not improve nitrogen release compared to each species applied alone under field conditions. This study shows that nitrogen release of prunings as a source of N to maize can be improved by managing pruning quality and the time and method of pruning application.. Farmers can manipulate one or more of these factors in order to gain maximum benefit of multipurpose tree prunings as an organic fertilizer resource.

10

PhD theses

Limits to predictability: on-farm spatial and temporal variability and the design of on-farm agroforestry trials

Andrew Pinney, PhD (Statistics), 1995

Supervisors: Prof. Roger Mead Dr Peter Huxley Dr James Roger

University: University of Reading, UK

Abstract Mono-cropped maize and beans were harvested for five seasons from arrays of small quadrats across twelve farmers' fields in a semi-arid area of Kenya. On five fields, Grevillea robusta seedlings were planted in a line of quadrats. All were farmer-managed, except the crop harvests and the tree management.

Analysis of the uniformity data was structured to address four design strategies, i.e. covariance analysis, spatial modelling of residuals, replication and prediction of position and orientation of blocks. Despite an average correlation between within-field yields of only 19%, covariance analysis was the most effective between dry seasons with larger square plots, especially on fields with consistent crop variation, and by avoiding the weaker areas. Plant number covariances were also more effective in larger plots. Trees showed increasingly strong temporal correlations, and therefore were more responsive to both prediction and covariance analysis.

Precision in space was reliably achieved with narrow plots stacked in small blocks placed to maximize intra-lot variation, with little or no guards. These plots gain from a spatial analysis, but the potential was reduced when guards were included because plots were larger and further apart. The inclusion of guards, even small ones, often doubled the variation in both crop and tree plots. Replication was an expensive option, with variation 36 times greater between fields than within-field. Prediction of precise placements and orientation was reliably achieved only in those fields with strong consistent patterns of crop variation, often created by tree/crop interfaces from trees outside the field, but there was no benefit in fields with less variability and consistent patterns.

The range of spatial correlation was the most temporarily stable factor, and was reliably predicted from visual scores of a low-level aerial photograph of the mid-season vegetative crop growth. These results are synthesized into a set of design guide-lines to help increase the precision of on-farm trials.

Issues in the utilisation of indigenous knowledge in agroforestry research

Flemming Nielsen, PhD, 1998

Supervisor: Professor Sofus Christiansen

U nlversity: University of Copenhagen

Abstract The aim of this thesis is to provide insight into aspects of indigenous knowledge whose understanding is crucial to achieve successful integration of indigenous and formal knowledge in agroforestry research.

PhD theses

First a historical overview is provided of experience from previous attempts to integrate indigenous and formal knowledge. It is shown that indigenous knowledge has always been utilised in agricultural research but the mode has changed over the last decades from being mainly extractive to become more participatory and facilitating.

Based on the author's own research and the literature, five issues are identified that need to be well understood if successful integration of indigenous and formal knowledge is to be achieved. The five issues are investigated in details through three case-studies of agroforestry in the lake-shore region of Uganda.

The first issue is farmers' knowledge generation that is of particular interest to participatory and facilitating modes of research. It is shown that perceptions of farmers' methods of knowledge generation varies widely in the literature and is rarely based on rigorous field-work. The evidence is often anecdotal, consisting of examples of farmers experimenting in ways similar to scientists. In a case-study of farmers' knowledge generation about the Albizia chinensis-banana agroforestry system, it is shown that farmers generated considerable knowledge over six decades without relying on experiments akin to scientists' experiments. Instead the knowledge generation process can be viewed as an unplanned collective experiment. Due to variations in bio-physical factors, history and agricultural practices between farms, each case of the agroforestry system is comparable to a treatment in a scientific experiment. As the system is adopted by an increasing number of farmers, more treatments are available for farmers to observe, ensuring that farmers' knowledge about the systems increases in width and depth.

It is shown that the role of nature through seed dispersal is crucial to the adoption rate of agroforestry systems and consequently for the rate of knowledge generation. Some farmers who never showed interest in the tree allow it to grow where it is self-sown and thus end up testing agroforestry layouts that farmers who plant the tree would never dare to test. These 'involuntarily experimenting' farmers can contribute to leaps in knowledge, whereas farmers who put more thoughts and effort into establishing the system are more likely to fine-tune existing knowledge.

It is argued that the role of experimentation in knowledge generation is generally likely to be smaller for slow-growing space-demanding crops and trees than for annual crops.

The second issue is farmers' networks that are of particular interest in facilitating approaches that aim at increasing innovation and diffusion rates through networking. In two case-studies farmers networks for the slow-growing Albizia chinensis and for the fast-growing vanilla are compared on two parameters: source of inspiration and source of planting material. The two networks have many structural similarities but one thing sets them apart: the frequency of exchange is high in the case of vanilla but extremely low in the case of A. chinensis. Several examples illustrate that the inefficient network for A. chinensis lead to farmers 'reinventing the wheel'.

The third issue is social distribution of knowledge because it is important to target the farmers who possess the right knowledge. It is shown that agroforestry knowledge and practice are intimately linked. By investigating agroforestry practices of different social groups their knowledge is assessed indirectly. In a case-study fanners' definition of wealth-groups is shown to correlate with selected variables from official statistics. Farmers' assessment of the relationship between wealth-groups and agroforestry is then combined with official statistics to paint a picture of the social distribution of agroforestry knowledge. Farmers did not think that gender or age was important in defining wealth groups. These two variables are investigated further and it turns out that status within the household is more important than gender per se, i.e. female-headed households practice agroforestry in a similar way to male-headed households. Age is shown to be important for the adoption of the new A. chinensis-banana agroforestry system.

12

PhD theses

The fourth issue is the dynamic nature of indigenous knowledge. Often indigenous knowledge is assumed to be static and just needs to be captured once. However, in two case-studies it is shown that indigenous knowledge can be highly dynamic and recorded knowledge quickly becomes a record of the past. Where knowledge systems are very dynamic only participatory and facilitating approaches stand a chance of fully utilising indigenous knowledge. Concern is often raised about disappearing knowledge but it is argued that the emerging knowledge has a bigger potential in development and research because emerging knowledge is often the first attempt to tackle tomorrow's problems.

The fifth issue is tacit knowledge. In a case-study it is shown that researchers with access to extensive surveys and years of experience can not imitate farmers' choices when they have to select the most promising agroforestry species from a research plot. It is argued that tacit knowledge is the problem and that tacit knowledge is likely to be more important in agroforestry with a long life-cycle than in annual cropping systems.

The sixth and last issue is spatial distribution of knowledge. This issue has been neglected in most research on indigenous knowledge. In two case-studies it is shown that different sampling strategies result in different knowledge being elicited.

In a concluding chapter five of the six issues are connected in an overall framework. These issues and the potential of different research methods are related to the length of the life-cycle of agricultural systems and to the continuum 'disappearing-common-emerging' knowledge.

Ecology and management of Uapaca kirkiana in southern Africa

Mzoma R Ngulube, PhD (Agroforestry), 1996

Supervisors: Dr JB Hall

Prof. JA Maghembe (ICRAF)

U niversity: University College of North Wales, Bangor, UK

Abstract

Uapaca kirkiana Mull. Arg., an important indigenous fruit tree of African miombo woodland, was studied for the nature of natural populations, aspects of reproductive biology and nursery activity. As relevant background, a comprehensive range-wide monographic account of the species was assembled. In sites where the species is abundant, a natural stocking of as many as 500 individuals/ha >10 cm dbh with a "balanced* size class distribution pattern is present. Male and female individuals are randomly distributed and generally within 10 m of each other. The sex ratio is generally approximately 1:1 and there is no obvious sex difference in mean tree diameter at breast height. Flowering and fruiting phases overlap appreciably and coincide with the rainy season. In Malawi, both sexes flower synchronously between October and April, with a peak period in February-March. A male inflorescence:female inflorescence ratio of 6:1 is estimated. Anthesis in female inflorescences lasts almost twice as long as male inflorescences and only the latter have any odour. A range of insects visit the flowers, apparently, for pollen awards, the most likely pollinators being bees, flies, beetles and ants.

There is significant provenance variation in fruit and seed traits, in germination and in seedling characters. Germination occurs within 30 days and most seeds produce seedlings. There is often,

13

PhD theses

however, a post-germination sclerotesta entrapment problem which halts further seedling development.

Through the monographic compilation, fresh insight was gained into ecological requirements through preparation of a distribution map from herbarium data and the interpretation of this in terms of environmental factors on a range-wide basis. It was ascertained that sites at >500>2000 m altitude with mean annual temperatures 18-290 C and mean annual rainfall >500 mm typify the range. Distinct occurrences in Angola were noted. These and peripheral populations under the harsher and milder extremes of conditions associated with the species should receive attention in provenance work.

It is concluded that the research priorities for Uapaca kirkiana are population dynamics and reproductive ecology, taxonomic interspecific relationships, vegetative propagation, provenance variation range-wide, seed storage, sex recognition (at the seedling phase), ectomycorrhizal symbiont, indigenous management, resource status and product quality.

The anatomy of innovation adoption: the case of successful agroforestry in East Africa

Bradley Philip Tyndall, PhD (Economics), 1996

Supervisors: Dr Alexandra Bemasek Dr Stephen Davis Dr Robert Kling Dr Steven Shulman

University: Colorado State University, Fort Collins, Colorado, USA

Abstract The silver oak (Grevillea robusta) has become a very common on-farm tree species in many parts of eastern Africa. In Kirinyaga, Kenya, where this study was completed, the tree is found in very large numbers on small private farms, about 40 per hectare, on 94% of the farms. To understand the reasons for the widespread adoption and its impact, holistic socioeconomic framework and data methods for adoption research were developed. The framework divides adoption into physical, economic and institutional aspects with many branches under each of these rubrics.

The researcher should first complete 'key informant' interviews, then 'key informant' surveys, then small topical surveys and larger quantifying surveys, consecutively.

The case study of the silver oak included five 'key informant' surveys and interviews, six topical surveys, and one 89-household survey. In addition, three crop and tree measurement activities were completed as part of an enterprise budget analysis. Potentially relevant adoption variables were identified from the interviews and small surveys. These variables were then included in the 89-household survey and were tested independent variables in regression models where the level of adoption was dependent variables.

The results indicate several reasons for grevillea's large-scale adoption. Physically, the tree has few natural roots which interfere with crops and it has a small crown to minimize the shading of crops. Socially, as part of a pre-colonial tradition, the tree serves to mark boundaries in an environment of land tenure insecurity. Economically, farms with the grevillea are over 4%t more profitable than farms without the tree. In terms of intangible costs and benefits, grevillea was

14

PhD theses

viewed as being equally as beneficial as beans and more beneficial than any other farm crop or tree.

The case of grevillea in eastern Africa supports the 'induced-adoption' or 'technology-pull' paradigm of innovation adoption. True to this paradigm, the tree technology was first adapted and then adopted to meet the land tenure and fuelwood exigencies of the area.

Given this induced-adoption paradigm of technology transfer, speculations were made as to prevent extension and development strategies. A 'technology scattering' strategy is introduced. This strategy entails advancing many 'half-baked' technologies through multidisciplinary extension teams.

Species selection for alley cropping in western Kenya: system management, nutrient use efficiency and tree-crop compatibility (1988 -1995 )

Arne M Heineman, PhD, 1996

Supervisors: Jeffrey Burley Peter Savill Philip Beckett

U niversity: University of Oxford, UK

Abstract When light and water are not the main limiting factors to crop growth and yield in tropical smallholder systems, nutrient management with or without the use of agroforestry trees and shrubs is the key to improved system performance and higher crop yields. In principle, a positive relationship exists between the quantities of nutrient recycled or added by trees in alley cropping systems and the additional alley maize yield, compared to the unmulched controls. This hypothesized relationship is primarily valid over longer periods of time, i.e. several seasons.

It is recognized that the food crop in an alley cropping system is invariably faced with a range of complementary benefits and competitive pressures as a result of the continuous presence of the trees. The thesis shows that leguminous trees and shrubs differ in the efficiency with which they can recycle and or add nutrients in alley cropping systems. Thereby, they vary in the ability to enhance crop yields and maintain soil fertility.

The observed tree species-specific differences result from variation in competitiveness with the annual crop(s). Observed differences are partly based on variation in nutrient concentration of tree leaves, and on differences in decomposition and nutrient release characteristics of those leaves, once they are applied as mulch. These and other factors ultimately translate into species specific differences in tree-crop compatibility in alley cropping systems. Thus, seasonal and long-term food crop performance and soil fertility status can be described in terms of the balance between the positive and negative contributions of the trees to the system.

The best tree-crop combinations are those where the net additions of nutrients by the trees to the crops are optimized, which is in most cases not synonymous with maximizing (above-ground) tree biomass productivity. However, trees in alley cropping systems must produce a minimum amount of high quality leaves for use as mulch in order to have a (measurable) positive impact on companion crop yields. Within the same tree species, higher food crop yields are positively correlated with provenances that produce more leaf biomass, provided the system is managed

15

PhD theses

properly. This does not necessarily hold when different tree species, with leaves varying in quality, are compared within the same alley cropping experiment.

Different tree species and provenances, when tested in a controlled, long-term alley cropping experiment (1988-1993), varied significantly in their ability to improve higher crop yields and maintain soil fertility. These observations subsequently formed the basis for adapting the agronomic concept of nutrient use efficiency in the context of alley cropping with leguminous trees and shrubs.

Nutrient use efficiency of maize grown in association with Leucaena leucocephala hedges is relatively low compared to the efficiency of maize use of inorganic sources of N, P and Ca at rates comparable to those applied via the tree mulch. This comparison of organic and inorganic fertilizer sources provides an opportunity to capture and express the competitive and complementary effects of L. leucocephala hedges in one quantifiable measurement, i.e. through the expression of the nutrient use efficiency of maize, when it is grown in close association with the trees.

Experiments are described which attempt to match the nutrient supply by trees with the seasonal nutrient demand by maize. This leads to the question how feasible it is in practice to synchronize the supply and demand for major, limiting nutrients by adjusting the management of the tree component. It is concluded that this requires extensive knowledge about the quality of the leaves, the quantities applied, the leaf decomposition and nutrient release patterns, the crop nutrient uptake requirements, their respective timing, and relevant climatic, weather and soils factors. Nine hypothetical scenarios about possible relationships between nutrient inputs and outputs are formulated as a basis to direct further work.

Alley cropping systems studied in western Kenya were mainly limited by the availability of major nutrients, including N and P. Using a glasshouse-based bioassay, different leaf types applied in different quantities and at different times, showed treatment-related effects on growth and yield of maize seedlings. Efficiency of use of the different leaf mulches by pot-based maize seedlings varied mainly by the leaf type used (i.e. tree species) and the quantities applied (rate). In the pot study, the nutrient uptake efficiency varied less in relation to variation in application times (effectively representing different states of decomposition), but controlling variation in the comparative levels of leaf decomposition was more difficult in the pot study than varying mulch types and rates of application. Using results of the bioassay, requirements for the design of short term, predictive pot studies were determined, where all three factors (mulch quality, quantity, time of application) are studied simultaneously. The bioassay results confirmed that variations between tree species and the application of their leaves during six years in alley cropping experiment in western Kenya were caused by significant variation in the nutrient use efficiency of maize (alternatively defined as nutrient transfer efficiency between system components) in different treatments.

Results of experiments from 1988 to 1995 in Kenya and the UK show that grain and stover yield responses of alley cropped and control maize in the field was primarily caused by variation in the relative availability of nutrients, facilitated by the presence or absence of trees, and less so by factors related to the availability of light and water. Nor were the observed yield effects in the field caused to any significant degree by below-ground interference with root systems in adjacent plots, in which case the experimental results would have been based (partly or wholly) on design artifacts rather than on experimental treatment effects. A quantitative technique was used to arrive at this conclusion.

The experimental results from the alley cropping experiment were translated into a set of simple yet powerful principles about what constitutes a suitable tree species for use in alley cropping under nutrient limited conditions, when light and water are not primarily limiting to the growth

16

PhD theses

and yield of the crop. These proposed characteristics and principles of tree-crop compatibility appear to have general applicability and the main idea behind them can be visualized in one single graph for a range of different tree-crop combinations and time scales.

Assessment and prediction of wood yield from agroforestry systems in Kenya

David Muriuki Kamweti, PhD, 1996

Supervisors: Prof. Ratemo Michieka

Dr N Karanja

University: University of Nairobi

Abstract

The aim of the study was to assess and predict the growth of wood in agroforestry areas of Embu District. The district was stratified into eight agro-ecological zones where a total of 14 746 trees were measured in 254 randomly-chosen farms. The species mostly investigated was Grevillea robusta. G. robusta was the most common tree species on most of the agro-ecological zones and had an overall weighted frequency of 37% out of the 104 species found in the sampled farms. Frequencies of the other 103 tree species found in various farms ranged from 0.001 to 11.4%.

Planted trees accounted for 83% of all trees found in the farms and the number of trees planted per ha was positively related to the population density. High-potential areas had more trees on farms than low-potential areas despite decreasing farm sizes. A spacing of 2 m was the most common for the trees, which were not open-grown. Boundary planting was the commonest pattern with a frequency of 42%. The yield of G. robusta ranged from 0.007 to 0.025 m /tree/year at ages three and six years respectively. Weighted mean volume of the species was 0.181 m /tree. Biological rotation was 8, 9, 10, 12, 15 and 15 years for agro-ecological zones three, four, five, six, seven and eight respectively.

Farmers felled trees at an early age because of increasing demand for tree products and a need to reduce tree crop competition. About 80% of G. robusta trees were harvested before attaining seven years, which was below biological rotation. Corresponding diameters and heights were less than 17 cm and 12 m respectively. Branch volume contributed an equivalent of about 26% of the stem volume.

G. robusta accounted for about 2.4 million trees with a volume of 440 000 m in all agro-ecological zones. Stocking of planted trees ranged from zero to 65 trees per hectare in the eight zones while that of regeneration trees was generally low with ranges of 1 to 12.

The wood yield models for zones three to nine indicated that diameter, height, age, spacing, land slope and tree crown height were the important independent variables which influence wood yield in farms and they were significant at 0.05% probability level. Diameter was the most important independent variable, which could be used to estimate tree volume with a precision level of 80%.

On validation, 57% of the sample plots indicated that there was no significant difference between observed and predicted volumes. Standard error of models ranged from 1.89 to 5.25% with a 95% confidence interval range of ± 4.50 to 2.93%.

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PhD theses

The diffusion of social forestry in semi-arid areas: a case study of Kitui District, Kenya

Alice Akinyi Kaudia, PhD (Social Forestry), 1996

Supervisors: Dr David Gibbon

Dr Frank Ellis

U niversity: University of East Anglia, UK

Abstract

Resource poor small-scale farmers are commonly target groups for rural development projects and social forestry is no exception. However, the concept of 'small scale farmers' masks the heterogeneity of rural farmers. This heterogeneity has important implications for technology generation and dissemination policies that could enhance social forestry technology adoption by farmers, and hence the diffusion of social forestry innovations. This research set out to identify the social and economic factors that influence the diffusion of social forestry innovations in semi-arid areas. The household was adopted as the unit of analysis. The goal and specific objectives of the research were pursued against a background of current discussions that are advocating reforms of institutional policies for social forestry technology generation and dissemination. The advocated changes seek to increase levels of participation by fanners in the generation and dissemination of social forestry innovations. This presumes that the participation of farmers in these processes will enhance the diffusion of social forestry innovations. However, in semi-arid areas where agro-ecological conditions constrain optimal biological productivity of trees in the short run, the need to sustain livelihoods can undermine adoption of technically profitable innovations. For this reason, the social and economic status of households has important implications for adoption and diffusion of social forestry innovations in marginal areas of developing countries.

This research was based in the Central Division of the Kitui District, eastern Kenya. The district has diverse agro-ecological conditions, but broadly the eastern part is largely a pastoral zone whereas the western part is predominantly a mixed farming zone. Fieldwork for this research was undertaken in the mixed farming zone.

The institutional context of generation and dissemination of social forestry innovations was examined as a background to understanding the congruency between approaches of projects in social forestry dissemination and social forestry information and knowledge acquisition by farmers. The research defined tree species and their cultivation as the social forestry innovations. It then focused on analysis of the differences between ranked preferences of the species by farmers and farmers' methods of integrating the preferred species into the farming system. The survey households were categorized by: (i) sex of head of household (ii) wealth status of household, (iii) availability of family labour, (iv) history of household settlement on the land, (v) 'ownership' of land, (vi) area of land operated, and (vii) affiliation of a member of the household with a women's group.

The main findings of this research are: • that area of land owned does have important implications for the intensification of on-farm

cultivation of trees as well as farmers' adaptive strategies for meeting their needs for tree product deficiencies

• that ownership of land in terms of social status of landowner seems to influence the types of trees grown by particular households

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PhD theses

• that farmers perceive their own experience and information from their neighbours as the main sources of social forestry skills.

The policy implications of these findings for social forestry research and extension are discussed in detail in the text. Broadly, the findings suggest a need for social forestry projects to adopt collegial farmer participation to enhance adoption of innovations by poorer farmers.

Tree-biomass decomposition, nitrogen dynamics, and maize growth under agroforestry conditions in the subhumid highlands of Kenya

Daniel N Mugendi, PhD, 1997

Supervisors: Dr PKR Nair Dr Henry Gholz Dr HL Popenoe Dr DM Sylvia Dr CK Hiebsch Dr DA Graetz

University: University of Florida, USA

Abstract Declining crop yields resulting from continuous cropping without external addition of adequate nutrients, are a major problem facing smallholder farmers in the tropics. The high cost of inorganic fertilizers has led to increased interest in the use of leafy biomass from woody species as a source of nutrients to annual crops. This thesis reports the results of a study conducted in the subhumid highlands of Kenya since 1992, on the influence of soil-incorporated leaf prunings of two agroforestry tree species (Calliandra calothyrsus, calliandra, and Leucaena leucocephala, leucaena) on maize yield and soil fertility status in sole cropping and alley cropping systems.

Inclusion of calliandra hedges on cropland (alley-cropping) adversely affected crop yields during the four year study, whereas alley cropping with leucaena increased crop yields. In all treatments, mineralization of soil N was at its peak four weeks after maize planting. Cumulative mineralization at week 20 ranged from 115 to 360 kg N/ha/season; the non-alley-cropped, non-fertilized control giving the lowest, and the prunings-incorporated treatments giving the highest amounts of N. Total N uptake by maize, ranging from 40 to 160 kg/ha/season, was lowest in the alley-cropped, prunings-removed plots, and the highest in the prunings-incorporated plots. Studies with N indicated that soil application of N-rich biomass contributed more to the long-term build up of soil N than to meeting the nutrient requirements of the current season's crop. The largest fraction of N (55-69%) in the tree biomass that was added to the soil was left in the soil N pool at the end of the current cropping season; 8-13% was recovered in the maize, 2-3% in the tree hedges; and 20-30% could not be accounted for.

A separate study on decomposition of tree-leaf biomass of some commonly used agroforestry tree species in the region revealed that the prevailing general assumption that decomposition of tree biomass is determined predominantly by plant quality factors was not always true: during seasons of erratic climatic changes (e.g. fluctuating temperatures), climatic factors were more important than plant quality factors in influencing the rate of biomass decomposition.

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PhD theses

Influence de Cordyla pinnata $ur la fertility d'un sol ferrugineux tropical et sur le mil et I'arachide dans un systeme agroforestier traditionnel au Senegal

Samba A Ndiaye Samba, PhD, 1997

Supervisors: Hank Margolis

Claude Camire

University: Universite Laval, Quebec, Canada

Abstract

Agroforestry parklands are agroforestry systems where trees are mixed with crops on the same unit of land. These tree-crop associations can have a positive, a negative or no effect on the soil or on the growth and yield of the plants. Foliar biomass production of the tree Cordyla pinnata was estimated to be 337 kg/ha in a parkland located in the southern part of the peanut basin of Senegal. Effects of crown volume, orientation, distance from the trunk and pruning intensity of C. pinnata on soil physical and chemical properties, nutrient contents, and millet and peanut growth and yield were studied. C. pinnata was not associated with any differences in soil physical properties (texture, bulk density or humidity). Soil organic C, total N, extractable P, exchangeable Ca and CEC (cation exchange capacity) were respectively 57%, 61%, 47%, 22%, and 15% higher under the canopy than in the open. For all pruning intensities combined, millet grain biomass (-18%) and total millet biomass (-0.5%) decreased significantly under C. pinnata. The biomass of peanut pods was also reduced (-25%) under the canopy compared to the open. Under the control (non-pruned trees), total biomass of peanut plants increased with distance (1486, 2084 and 2110 g/m) while under completely pruned trees, total biomass of peanut plants decreased with distance (2177, 1829 and 1787 g/m). Millet and peanut yields and nutrient contents were studied using two bioassays in a nursery: (1) soils sampled at different distances from C. pinnata and (2) soils mixed with different quantities of C. pinnata litter (0, 39, 78 and 156 kg litter/t soil). Millet and peanut plants grown on soils sampled under C. pinnata had a higher yield than those grown on soils sampled away from the canopy. Total biomass of peanut plants was reduced by litter additions (-11%, -13% and -29% respectively with 39, 78 and 78 kg litter/t soil).compared to the control. Total biomass of millet was increased 17, 1.9 and 1.5 times by the same treatments. K content in peanut leaves also increased with litter additions but N, P, and Ca in millet grains varied greatly.

The interception of precipitation by C. pinnata was studied in relationship to tree crown volume, distance from the tree and relative light intensity. Under full canopy, 22% of gross precipitation was intercepted. There was a positive asymptotic relationship between gross precipitation and interception. The canopy storage capacity of C. pinnata was 5 mm.

Germination du palmier doum (Hyphaene thebaica Mart.) et analyse de son interaction avec le mil (Pennisetum glaucum L) en zone semi-aride du Niger

Hassane Moussa, PhD, 1997

Supervisors: Pierre-Andre Dube Hank Margolis

University: Universite Laval, Quebec, Canada

20

PhD theses

Abstract Des traitements par la scarification mecanique et chimique, le trempage dans l'eau et leurs combinaisons appliques aux semences de palmier doum {Hyphaene thebaica Mart.) fraichement recoltees des ecozones du nord, du centre et du sud de la vallee du fleuve Niger, le meilleur taux de germination est obtenu avec les semences noyaux de l'ecozone du sud trempees pendant trois jours dans l'eau courante. Cependant, pour les vieilles semences du sud, le meilleur taux de germination est obtenu avec les semences sans pericarpe enterrees et arrosees pendant 11 jours. Le taux de germination des semences de palmier doum diminue de 29.1 % apres 13 mois de conservation. Le trempage dans l'eau des fruits entiers donne un taux de germination tres faible (0 a 7.5 %). Par contre, le trempage de 30 mm en acide sulfurique concentre (90 %) des semences intactes de 13 mois donne un taux de germination de 28 %.

Sur arenosol a Kareygorou, les niveaux de N, P, K, M.O., Mg, Ca et le pH des sols, ainsi que le rendement du mil sous les Hyphaene thebaica Mart, (arbre ou buissons) sont superieurs a ceux obtenus sous les Faidherbia albida Del. Chev. (arbres) et sur terrains nus. Par contre, sur regosol a Say, le rendement du mil ainsi que les contenus du sol en N, K, M.O, Mg et Ca sont plus eleves sous les Faidherbia albida Del. Chev. (arbres). Le rendement du mil et la fertilite des sols sous ces deux especes d'arbres sont nettement superieurs a ceux des terrains nus. Sur arenosol et regosol, le niveau du phosphore et du pH sont plus eleves sous les Hyphaene thebaica Mart, (arbres ou buissons) que sous les Faidherbia albida Del. Chev. (arbres) et sur terrain nu. Sous ces deux types d'arbres, le niveau de fertilite et le taux d'humidite des sols, ainsi que le rendement du mil decroissent mesure que Ton s'eloigne des troncs.

Management of Calliandra calothyrsus in association with Pennisetum purpureum for increased dry season forage production on smallholder dairy farms in central Kenya

Zachariah Obadiah Nyaata , PhD (Agroforestry), 1998

Supervisors: JDH Keatinge PT Dorward Dr Mick O'Neill (ICRAF)

U niversity: University of Reading, UK

Abstract Smallholder dairy production in Kenya is seriously constrained by inadequate fodder especially in dry seasons. An adequate nutrient supply is further hindered by qualitative deficiencies, as a result of the peculiar growth characteristics of the basal napier grass forage that grows and matures rapidly with the onset of the rains thus becoming fibrous and deficient in nitrogen and soluble carbohydrates. Crop residues which constitute another important and often major feed resource used during the dry season for improving the consumption and digestibility of crop residues are often inappropriate for smallholder farmers because of the non-availability of chemicals, health risks and cost of additional labour to collect and cut the residue. Inclusion of leguminous fodder shrubs in the farming system could address this problem.

A study was carried out in the central highlands of Kenya to investigate dry season forage production using napier grass in a 2:1 association with calliandra. Sole stands of napier grass and calliandra were included as control treatments. The effect of three levels of cattle manure and fertiliser nitrogen and phosphorus at levels potentially supplied by the cattle manure was assessed.

21

PhD theses

Studies on the effect of three intervals of cutting calliandra on the yield and quality of forage from the mixtures were also carried out. The experiment was planted in October 1995, preceded in September 1995 with an on-farm study of the availability and use of dry season feed resources on smallholder dairy farms in the area. The survey results and two years of observations on the experiment are reported.

The survey results showed that most farmers in the central highland of Kenya depend on napier grass to supply the bulk of the roughage requirement for their animals. Four out often farmers, however, offered between 5 and 45% less forage than the daily potential dry matter requirements of their animals.

The presence of calliandra in the mixture increased the crude protein content of napier grass and contributed up to 230 kg N/ha in harvested forage. The two months frequency of harvesting calliandra had the best performance in edible calliandra fodder yield as well as understorey grass production in the two years. Higher total crude protein and digestible dry matter yield was also obtained from the two months frequency treatments. The two months cutting interval treatments, however, gave the least overall fuelwood and dry season understorey grass production.

Grass response to cattle manure and fertiliser nitrogen and phosphorus application was gradual and is expected to continue, but tree fodder yield was unaffected by the different levels of cattle manure and the inorganic fertiliser application. Total crude protein yield was increased by increasing levels of cattle manure application.

In the first few months of establishment, napier grass yields in the mixtures were not affected by the presence of calliandra but in the subsequent harvests calliandra had a substantial negative effects on the grass yield.

Practical implications of the results are discussed and future research work suggested.

22

Theses submitted for the degree of Master of Science

(MSc) and Master of Philosophy (MPhil)

Biomass, volume and nutrient accumulation by six-year old Acacia albida under agroforestry at Mafiga, Morogoro, Tanzania

John Okorio, MSc (Forestry), 1987

Supervisors: Prof. Jumanne A Maghembe Dr Luther L Lulandala Dr Shabani Chamshama Dr Aku O'Kting'ati

University: Sokoine University of Agriculture, Morogoro, Tanzania

Abstract The study was conducted to evaluate the suitability of Acacia albida for fuelwood and fodder production using agroforestry in a semi-humid environment at Mafiga, Morogoro. The trial was planted in February, 1980, and arranged in a split-plot design with three main plots: Acacia intercropped with maize, Acacia intercropped with beans, and Acacia monoculture clean-weeded.

Each main plot included four tree spacing subplots: no trees, trees planted at 4 x 4 m, 5 x 5 m and 6 x 6 m. The experiment had four replications covering an area of 4.32 ha.

In March 1986, thirty trees representing all the diameter classes in the trial were harvested and used to determine volume, biomass and nutrient content. In addition, eight root systems were excavated to determine root distribution, biomass and nutrient content. Seventy-two soil samples were collected from the different treatments and analyzed for macronutrients. Data on height, diameter growth and food crop yields (maize and beans) for the past six years was compiled from past records.

At the age of six years, the mean height and diameter at breast height for Acacia albida in the whole trial was 8.41 m and 10.7 m respectively. Intercropping or tree spacing did not affect height growth, but diameter growth was affected by tree spacing.

Volume production varied from 9.9 to 24.9 m3 /ha and total biomass values ranged from 19.6 to 43.1 tons/ha. Intercropping did significantly (p<0.05) influence both volume and biomass production with higher volume and biomass under lower spacing and the lowest volume and biomass under the highest spacing.

Nutrient concentrations were high and comparable to other tree legumes. Generally, nutrient concentrations were highest in the foliage and brushwood and least in the stem, with intermediate concentrations in the roots and branches.

Except for N, the nutrient accumulations were highest in the stem, brushwood and roots, with the least amounts found in the foliage and branches. The highest inventory of N was concentrated in the foliage. The total nutrient accumulation in the aerial biomass at the closest spacing (4 x 4 m) in

MSc and MPhil theses

kg/ha were 262.9 N, 39.4 P, 156.7 K, 97.4 Ca, 57.6 Mg and 73.8 Na. Corresponding values for the below ground biomass were 85.0, 8.1, 54.3, 23.5, 18.1 and 8.1 kg/ha.

Although there were trends of increasing nutrients under the trees the presence of Acacia trees did not significantly influence the nutrient status of the soil. Food crop yields varied from 143.2 to 409.7 kg/ha for beans and 343.8 to 956.0 kg/ha for maize. The yields of the food crops were not significantly affected by the presence of the trees. The Acacia albida root system developed a taproot with lateral roots growing downwards. At the age of six years, the mean taproot length was 2.84 m, and the mean diameter of lateral roots varied from 1.40 to 2.30 cm, while their mean length varied from 1.64 to 2.32 m. The root system is uniformly distributed within the soil profile, but with a higher proportion of lateral roots at depths greater than 20 cm. The fine roots, however, are concentrated in the top 30 cm of the soil.

The effects of Acacia albida on food crops and soil fertility and the suitability of the species for village woodlots as a source of fuelwood and fodder are discussed.

A study of alley cropping maize and green gram with Leucaena leucocephala (Lam.) De Wit at Mtwapa, Coast Province, Kenya

Bashir Jama, MSc (Agronomy), 1988

Supervisors: Prof. DN Ngugi

Dr Amare Getahun

University: University of Nairobi, Faculty of Agriculture, Kenya

Abstract Crop yields in the Kenya coastal lowlands are low because of poor soil fertility and high weed infestation. The sandy soils (92% sand), deficient in all major nutrients (N, P, K), are highly leachable and fertilizer application is necessary for good crop yields. Green leaf manure from Leucaena leucocephala hedgerows (alleys) established in a split-plot systematic design with 5-replications was incorporated to boost soil fertility, by cutting hedgerows to 0.5 m height two weeks before maize crop planting. Two additional cuttings were made during the cropping season for additional green leaf manure and to minimize leucaena shading of the crop.

Assessment of crop yields and monitoring of soil fertility trends was carried out over a period of four years (1982-85). It was observed that the usual trend of soil fertility decline that normally results with continuous cropping was reversed with the use of leucaena alley farming. The system was even able to increase maize yields by 38% after four continuous cropping years, except for the period of tree establishment and pruning during which crops were significantly reduced due to excessive shade effect.

Soil tests also showed a gradual increase in soil percentage of organic carbon, phosphorus, potassium, calcium, magnesium and pH over the control plots. This was due to the high organic N-additions, up to 283kg N/ha from leucaena green leaf manure, nutrient release from tree root death and decomposition, and finally, nutrient savings from uptake by weeds. In general, the higher the tree density/ha, the higher the concentration of soil nutrients including an increase in soil pH.

24

MSc and MPhil theses

Plant nutrient aspects of mulch incorporation in alley cropping trials of semi-arid Machakos, Kenya

Daniel Njiru Mugendi, MSc (Agroforestry), 1990

Supervisors: Dr BO Mochoge Dr CL Coulson Prof CJ Stigter Prof Kenneth F King

University: University of Nairobi, Kenya

Abstract Experiments on plant nutrient status and yield of maize in relation to mulch nutrient composition were conducted at Katumani in Machakos District from 1987 to 1989. In all the seasons, Katumani B Composite was sown, apart from the short rains of 1988, when Hybrid 511 was planted.

Cassia siamea had been grown as the tree species forming the hedges. Between the hedges, three maize rows were sown parallel to the hedges. The hedges were lopped periodically at a height of 50 cm and the loppings fully incorporated into the soil within the hedges (alleys) before the beginning of each season. In the control plots, each hedgerow was replaced by a row of maize and no mulch incorporated.

Nutrient analysis was performed primarily for macronutrients, N, P, K, Ca and Mg for cassia loppings, maize leaves, maize grains and maize stovers. Maize yield (grains) in g/row and weed biomass were also assessed. Decomposition for Cassia siamea loppings using standard litterbags was also monitored.

The results indicated that incorporation of mulch increased the nutrient concentrations of maize leaves, grains and stovers as revealed by higher levels of nutrient concentrations in the treated plots relative to the controls. Although there was a relatively higher yield in the treated plots as compared to the controls on per row basis, the differences were not significant. The weed biomass in the treated plots was more than in the control plots. Decomposition experiments indicated that approximately 70-90% of cassia mulch dry matter could be lost within 60 days.

Acacia, ieucaena and sesbania green manures affect maize growth in the Tabora region of Tanzania

Donati A Asenga, MSc (Forestry), 1991

Supervisors: Dr Douglas O Lantagne Dr Michael A Gold Dr Darryl D Warncke

University: Michigan State University, USA

Abstract A pot experiment was used to examine the green manure of Leucaena leucocephala, Sesbania sesban and Acacia julifera on maize growth. In conjunction with the pot experiment, a

25

MSc and MPhil theses

decomposition study for the same tree species was also conducted. Three levels of green manure — 0, 4, and 8 tons/ha for each tree species — were used. Maize dry matter yields of treatments incorporating green manure of L. leucocephala were 70 to 190% higher than controls and 14 to 70% higher than those of S. sesban. The use of green manure from A. julifera did not affect maize dry matter yield. Maize dry matter yield increased as the amount of green manure increased.

Inorganic and organic phosphorus transformations during 18 years of cultivation in the Amazon Basin

Michel A Beck, MSc (Soil Science), 1991

Supervisors: Pedro A Sanchez (ICRAF) M Davidian SW Buol

University: State University of North Carolina, USA

Abstract Soil phosphorus dynamics, the transformation and pathways among different P pools, are poorly understood in natural and managed systems in the humid tropics. This study was undertaken to determine the inorganic and organic P pools acting as sources and/or sinks in a fertilized and unfertilized (control) crop production system during 18 years of cultivation following slash and burn of a forest fallow.

The inorganic P (Pi) pools control plowlayer (0-15 cm) P dynamics in the fertilized plots. Available, labile, and moderately labile Pi levels follow the pattern of annual P application rates. Inorganic phosphorus dynamics begin to stabilize 12 years after burning when available Pi level is maintained above the established critical level by annual P application rates of 60 kg/ha.

Factor and path analysis indicate that organic P (Po) pools have only a minor role in fertilized pools. Calcium-phosphate fertilizer reaction products are strongly linked to labile and moderately labile Po as a source of P for organic P accumulation, which in the fertilized plots stabilized at slightly higher than original level.

In the control system, organic carbon correlates highly (p<0.01) with labile Po, r = 0.92, and moderately labile Po, r = 0.72. Organic P pools are the main source of plant available Pi, but are unable to maintain available Pi above critical levels for crops. Soil chemical properties in the control plots favour P retention by the residual P pool that acts as a sink in the system's P dynamics.

During 13 years (1972-1985) and 31 crops, 1271 kg P/ha was applied. Of the applied P, 577 kg/ha was removed by harvest, 207 kg/ha accumulated in the top 15 cm, and 327 kg/ha translocated into the sub plowlayer (15-40 cm), while 160 kg/ha (12.7%) of applied P is unaccounted for.

Control plots received 103 kg/ha during 13 years, while 29.5 kg was removed by harvests. Plowlayer total P increased by 4 kg and the sub plowlayer by 42 kg P/ha, while 27.5 kg/ha (26.7%) of the applied P is unaccounted for.

26

MSc and M Phil theses

Decomposition of leaves from N-fixing trees in Zambian agroforestry

Robson D Mwiinga, MSc (Environmental Science), 1991

Supervisors: Dr Edwin H White

Dr Freddie Kwesiga (ICRAF)

University: State University of New York, New York, USA

Abstract Low crop production, largely attributable to poor soil fertility status, is a critical problem in Zambia. Agroforestry using improved fallow technology, and applying leaves of N-fixing trees and shrubs as a green manure, is a possible solution. The objectives of the study were to investigate the green manure system, specifically to determine (i) whether decomposition rates of foliage differ among the multipurpose trees Leucaena leucocephala (LEL), Flemingia congesta (FLC), Pericopsis angolensis (PEA), Cassia siamea (CAS), Sesbania sesban (SES), and Gliricidia sepium (GLS), (ii) whether N, P and K concentrations of foliage differs among these species, and (iii) whether N, P and K content release from foliage differs among them.

Litter bags containing foliage from each species were arranged in a randomized block design with three replicates. Litter bags were sampled at 0, 2, 4, 8 and 12 weeks in a repeated measures manner, after placement to determine decomposition and nutrient release.

Estimates were made of nutrient mineralization and equations developed for predicting rate of decomposition nutrient concentration, and nutrient content for each species. Significant differences existed in decomposition rates (GLS>LEL=SES>CAS>PEA=FLC), N contents (GLS=LEL)>SES>(PEA=FLC=CAS), P concentrations CAS>(SES=FLC=GLS=PEA=LEL), P contents (GLS=LEL)> CAS=PEA=SES=FLC), K concentrations (GLS=LEL=SES)>CAS>PEA>FLC and K contents (GLS>LEL>SES>PEA>CAS>FLC). No significant differences existed in N concentration.

Effect of pruning frequency on the yield of maize/cowpea in a Leucaena alley cropping system

Tiki Manga Theophilus, MSc (Agroforestry), 1992

Supervisors: Dr SJ Quashie-Sam Dr EY Safo Dr Bahiru Duguma (ICRAF)

University: University of Science and Technology, Kumasi, Ghana

Abstract A 48-weeks' period study was conducted at the Institute of Renewable Natural Resources' farm, UST, Kumasi, Ghana (6°43'N; 1°36'W) on a four-year-old plot of Leucaena leucocephala (Lam.) De Wit to assess the effect of cutting frequencies on biomass production and maize/cowpea yield. The experiment was carried out on a Feric Acrisol and laid in a split-plot design with randomized complete blocks replicated three times. The treatments were mulching as the factor with two levels (no mulch, with mulch) whereas the sub-treatment was the pruning frequency with five levels (4,

27

MSc and MPhil theses

6, 8,10 and 12 weeks). It was an alley cropping system in which leucaena trees formed the hedgerows with 5 m x l m row spacing and the test crops used were cowpea (Vigna unguiculata) var. Asontem and maize (Zea mays) var. Abeleehi, an early-maturing variety respectively cropped in the minor and major cropping seasons. The biomass production (fresh and dry yield) and the labour use for cutting the trees and applying the mulch were monitored for leucaena. Cowpea grain yield and maize production parameters such as stand density, plant height, biomass and grain yield were recorded. Soil was analysed to determine the impact of the various treatments on the soil physical and chemical properties.

The results revealed that leucaena biomass yield (green manure or dry matter) increased significantly with decreasing cutting frequencies, i.e. 12-week pruning level produced the highest biomass yield whilst 4-week pruning level produced the lowest yield. However, the labour used for both cutting the trees and applying the mulch decreased with increasing pruning frequency. Cowpea yield was very low in general, irrespective of the treatments assigned, with no significant response. However, the 4-week cutting interval produced a relatively high grain yield while a 12-week pruning level produced the lowest yield. Cowpea grain yield decreased pruning frequency while with mulch production was lower than the unmulched plot. There was significantly higher maize yield with medium pruning frequencies (6 and 8-week pruning level); low grain yields were obtained with low pruning frequency (12-week pruning level).

The study therefore indicated that medium cutting intervals are suitable both for biomass yield and crop (maize) grain yield during the cropping season and that low pruning frequency (12-week pruning level) can be adopted in the dry season to avoid tree dieback and to supplement fodder for livestock whereas high pruning frequencies (4-week pruning level) are to be avoided. Intercropping biological nitrogen-fixing crops like cowpea with leguminous shrubs or trees is not suitable in an alley cropping system. But non-nitrogen fixing crops (maize for example) respond better when associated with leguminous trees. There was minor or no significant changes recorded in the soil physical and chemical properties. It was concluded that a long term study (three to four years) might yield significant changes in the soil properties.

Evaluation of the nutritive value of some selected multipurpose trees and shrubs (MPTS)

Emmanuel Kwasi Ntiri, MSc (Agroforestry), 1993

Supervisors: Dr SJ Quashie-Sam

University: University of Science and Technology, Kumasi, Ghana

Abstract Acacia auriculiformis, Albizia adianthifolia, Albizia lebbeck, Albizia zygia, Cajanus cajan, Calliandra calothyrsus, Cassia siamea, Cassia spectabilis, Gliricidia sepium and Leucaena leucocephala were evaluated for their feeding value to sheep. Their foliage was analyzed for dry matter, organic matter, ash, crude protein, crude fat using AOAC (1984) methods of Georing and Van Soest (1970). The determinations were done in both the wet and dry season plant harvest for comparison. The in vitro dry matter digestibility was also determined for both seasons using the methods of Tilley and Terry (1963). Foliage of Albizia zygia, Albizia lebbeck, Cassia siamea, Cassia spectabilis, Leucaena leucocephala, Gliridicia sepium and Acacia auriculiformis were harvested during the dry season, air-dried and used in supplementary feeding trial with cassava peelings as basal diet to determine their suitability as dry season supplements for sheep.

28

The ten multipurpose trees differed in their nutrient composition in both seasons (p<0.01) except for the acid detergent fibre for the dry season where there were no significant differences among the species. Dry matter values ranged between 38.6% (Albizia zygia) and 20.0% (Gliricidia sepium) for the wet season and 73% (Gliricidia sepium) and 46.6% (Albizia lebbeck) for the dry season. Crude protein values ranged between 32.5% (Leucaena leucocephala) and 20.0% (Acacia auriculiformis) for the wet season, and 27.5% (L. leucocephala) and 17.5% (Albizia zygia) for the dry season on dry matter basis while the lignin values for the wet season ranged between 31.9% (Albizia zygia) and 7.3% (Albizia lebbeck) and the dry season values ranged between 18.5% (A. zygia) and 4.4% (Calliandra calothyrsus and L. leucocephala) all on dry matter basis. The acid detergent fibre values ranged between 45.6% (A. zygia) and 12.8% (L. leucocephala) for the wet season and 37.9% (A. zygia) and 15.0% (L. leucocephala) for the dry season on dry matter basis. Crude fat however ranged between 7.0% (Cajanus cajan) and 1.1% (Acacia auriculiformis) for the dry season. Apart from the differences among species within a season, for each species, there was a significant difference in nutrient composition between the dry season and the wet season. Generally, acid detergent fibre, crude protein and lignin decreased while crude fat and cellulose increased during the dry season. However, the t-test showed that, for ash, neutral detergent fibre and hemicellulose, there were no significant differences in the overall means of the ten multipurpose trees between the wet season and the dry season.

The wet season in vitro dry matter digestibility ranged from 23.5% (Acacia auriculiformis) to 75.8% (L. leucocephala) while the dry season values ranged from 18.0% (Albizia zygia) to 72.5% (Cassia siamea). For most of the species, the dry matter digestibility improved during the dry season, but there was no significant difference between the overall means of the ten species for the two seasons.

In the supplementary feeding trial, two levels were fed for each species. These are 60 g and 120 g air-dry weight (7.0% moisture). The unsupplemented treatment (control) had the lowest mean daily dry matter intake (60.4 g/kg W0.75). The 120 g supplementary levels enhanced greater intake of dry matter than their respective 60g levels. The 120 g supplements enhanced total dry matter intake ranging from 76.0 g/kg W0'75 (Albizia zygia) to 69.1 g/kg W0'75 (Albizia zygia) and 52.5 g/kg w0.75 (Cassia siamea). Cassia siamea seemed to contain some anti-nutritional factor or lacked some nutrient that induced lower intake and caused drastic reduction in weight of the animals.

Daily water intake of sheep ranged between 93.1 ml/kg w 0.75' (Albizia lebbeck) and Gliricidia sepium) and 68.2 ml/kg w 0.75 (Cassia siamea) for 120 g supplementary levels. The 60 g supplementary levels ranged between 92.7 ml/kg W0.75 (Albizia lebbeck) and 58.5 ml/kg W0'75

(Cassia siamea). The control however, induced the lowest water intake (52.5 ml/kg W0.75). There was correlation between total dry matter intake and water intake (P<0.05). There was, however, no significant variation in water intake among the supplementary treatments.

The mean daily weight gain was between 18 g/day (Cassia siamea) and 78 g/day (Gliricidia sepium) for 120 g supplement levels and 20 g/day (C. siamea) to 87 g/day (Acacia auriculiformis) for 60 g supplements. The unsupplemented treatment (control) produced weight of 33 g/day.

The ten multipurpose trees were ranged based on their crude protein, acid detergent fibre, neutral detergent fibre and lignin constituents as determined for the dry season, wet season and the values of both seasons combined. L. leucocephala exhibited best quality factors in all the three ranks.

29

MSc and MPhil theses

The potential use of contour hedgerows for soil erosion control in the highlands of Kabale District, southwestern Uganda

Adison Kakuru, MSc (Agroforestry), 1993

Supervisors: Prof Julius Zake Dr JohnAluma Dr Donald Peden (ICRAF)

University: Makerere University, Uganda

Abstract The purpose of this study was to investigate the effectiveness of Calliandra calothyrsus hedgerows and napier grass (Pennisetum purpureum) strips as understories under varying intra-row spacing of Grevillea robusta for soil erosion control in the highlands of Kabale District, southwestern Uganda.

Thirty erosion plots were imposed on an existing upperstorey-understorey management trial to sample soil and water loss on steep cultivated slopes. A one litre representative sample from the total run-off of each plot was left to settle for four days. The clear water was decanted off and the sediments were oven dried to constant weight at 1050 C. Soil samples collected up-slope and down-slope from the hedgerow were subjected to physical and chemical analyses. The analyses included determination of nitrogen, phosphorus, potassium, sodium, calcium, organic matter content, pH and texture.

Napier and calliandra significantly (p<0.001) reduced soil loss relative to control by an estimated 68.0 and 55.6% respectively. Other qualitative characteristics of napier strips and calliandra hedgerows evident in this experiment are discussed. There were no significant differences (p<0.05) in soil loss among the different upperstorey intra-row spacing of grevillea. The results from the soil analyses indicated that there were significant (p<0.05) differences in organic matter content, among the understorey treatments. Soil organic matter under napier appears to have increased by an estimated 24% relative to the control.

From results of this study, hedgerow intercropping is highly recommended for soil erosion control in Kabale highlands but by-laws should be enacted to prevent livestock from damaging young trees. Further research work to determine optimal inter-hedgerow spacing for the different species of shrubs and grasses and the costs and benefits involved for the smallholder hill farming system is recommended.

Water and crop biomass dynamics in a Cassia siamea Lam. and Zea mays L. alley-cropping systems

Francis Muriu Kanja, MSc (Forestry), 1994

Supervisor: Dr Kenneth M Brown

University: Lakehead University, Ontario, Canada

Abstract Alley cropping is a crop production system in which food crops are grown in the alleys created by hedgerows of selected tree species, preferably legumes. The objective of this study was to model a

30

MSc and MPhii theses

Cassia/maize alley cropping system in the semi-arid district of Machakos in Kenya. The modelling was done with respect to the system's ground water dynamics as it affects its biomass production. First the dynamics of water in a bare soil were modelled, and then cassia and maize were introduced separately and their biomass production modelled with respect to water. Finally, a combined cassia/maize/groundwater model was build and analyzed. The model suggests that water is a critical factor in the biomass production of cassia and maize. The main achievement of this project has been to provide a starting point for a framework in which empirical research results can be integrated and interpreted in a more holistic manner.

Identification and characterization of browse plants in Kumasi District, Ashanti Region of Ghana

William jasper Asante, MSc (Agroforestry), 1994

Supervisors: Mr SK Oppong Mr JGK Owusu Dr SJ Quashie-Sam

University: University of Science and Technology, Kumasi, Ghana

Abstract Inadequate nutrition is one of the most serious constraints to livestock production in sub-Saharan Africa. The importance of browse plants in overcoming feed shortage has long been recognized but not much has been done in evaluating their nutritional values.

This study which was carried out in two phases, first aimed at identifying the various browse species used as fodder by livestock farmers in the Kumasi District of Ghana. This was followed by the nutritional analyses of the identified species.

A two-stage stratified sampling technique was adopted to delineate the district into nine zones. This was followed by random selection of two towns in each of the nine zones. In each of the selected towns, five farmers were interviewed on browse utilization with the help of questionnaires. Data was also collected on animal types, farming systems and feeding management over a five-month period.. The second phase entailed chemical analyses of the identified species in terms of crude protein, either extract, detergent fibres or in vitro digestibility.

Results of the survey showed mat browse is utilized as a supplementary feed to a basal feed of dried peels of cassava and plantain. Fourteen browse plants were identified as being commonly used. The most highly preferred species is Ficus exasperata with a preference index of 77.8%. Ficus umbellata (33.8%), Griffonia simplicifolia (30.0%), Baphia nitida (27.8%), Ficus leprieuri (27.8%) and Spondias mombin (25.6%) were also preferred but to lesser degrees.

Albizia zygia had the highest crude protein content of 32.0%, but a very low in vitro dry matter digestibility (IVDMD) of 19.4%. Alchornea cordifolia with the lowest crude protein content of 13.4% had an appreciable IVDMD value of 41.4%. There was a weak positive correlation between crude protein content of the species and their digestibility probably due to some anti-nutritive substances. Similarly, there were negative correlation between the detergent fibres and their digestibility. Generally, the high levels of the detergent fibres (neutral detergent fibre, acid detergent fibre and lignin) negatively affected the rate of digestion.

31

MSc and MPhil theses

In ranking the browse plants as fodder, two factors were considered: farmers' preference indices and chemical composition. Ficus exasperata was rated as the most promising browse plant in the study area. The least ranked species were Albizia zygia and Thalia geniculata.

Decomposition and nutrient release patterns of leaf mulches of Leucaena leucocephala, Gliricidia septum and Cassia spectabilis

Takyi Sraha, MSc (Agroforestry), 1994

Supervisor: Dr Francis Ulzen Apiah

University: University of Science and Technology, Ghana

Abstract The rate of decomposition and nutrient release patterns of leaf mulches of Leucaena leucocephala, Gliricidia sepium and Cassia spectabilis were investigated under field conditions" using wooden square frames over a period of 70 days. The experiment design used was a complete randomized design with three replications using the tree species as treatments. Fresh leaf mulch weighing the equivalent of 100 g dry weight of the species was spread in the wooden frames, sampled every two weeks and the weights and the concentrations of C, N, P, K, Ca and Mg determined. Soil under the wooden frames was sampled at 10-15 cm and 15-30 cm profile depths every two weeks and analyzed for C, N, P, K, Ca and Mg. The initial chemical characteristics of the leaf mulches were also determined.

Decomposition rates of the leaf mulches differed significantly (P<0.05) and followed the order: L. leucocephala > G. sepium > Cassia spectabilis. The half-life values were 18 days fox L. leucocephala, 35 days for G. sepium and 69 days for C. spectabilis.

Initial concentrations of nutrients and percentage lignin in leaf mulch of the species varied significantly (P>0.05). G. sepium had the highest concentrations of phosphorus (0.45%), potassium (2.8%), calcium (1.40%) and magnesium (0.44%/ Leucaena leucocephala had the highest nitrogen (3.85%) and carbon (46.20%). Percentage of lignin was 5.6 in L. leucocephala, 7.6 in G. sepium and 8.7 in C. spectabilis.

Generally, potassium showed the highest release rate with nutrient release constant (K) ranging between 0.018 in C. spectabilis and 0.045 in G. sepium. The release of the nutrients from the leaf mulch were ranked as follows: K > Mg > N > P > C > Ca for L leucocephala, K > Mg > P > N > = Ca > C for C. spectabilis. The chemical characteristics of the mulch material especially the percentage of nitrogen and lignin, played key roles in determining the rate of decomposition and nutrient release.

Soil nutrient levels improved significantly under the decomposing leaves at both 0-15cm and 15-30 cm profile depths. The general order of improvement in soil nutrient content at 0-15 cm depth of profile was N > K > Mg > Ca > C> P for L. leucocephala and G. sepium and N > K > Mg > C > Ca > P for C. spectabilis. At the 15-30 cm depth the trend was N > K > Mg > Ca > P > C for the three species.

32

MSc and MPhil theses

The effect of season and shrub-grass combination of the fodder quality of three agroforestry plant species grown in Maseno, western Kenya

Edward Kibet Mengich, MSc (Forestry), 1994

Supervisors: Dr JP Kimmins Dr Daniel Nyamai Mr Harry Otieno (ICRAF) Mr Dirk Hoekstra (ICRAF)

University: University of British Columbia, Vancouver, Canada

Abstract An experiment to study the effect of season and shrub-grass combination on the fodder quality of leucaena (Leucaena leucocephala), calliandra (Calliandra calothyrsus) and napier grass (Pennisetum purpureum) was established at Maseno, western Kenya. The species were managed as hedgerows on field bunds in a randomized complete block design with seven treatments and four replications. Fresh and dry leafy biomass assessments, and sample collection were done at two-month harvesting intervals for 18 months. Percent dry matter was determined by oven-drying about 500 g of fresh samples at 60 C for 48-72 hours. Dried samples were ground to pass 1 mm sieve and analyzed for N (used for crude protein estimation), P, Ca, K, Mg, Zn, Cu and acid detergent fibre. Statistical analysis was done using SAS 6.04 at a = 0.05 significance level.

Napier grass was highest in fresh and dry biomass productivity. Biomass productivity, however, dropped significantly in the second year. Biomass productivity of shrubs was lower, but was maintained at similar levels throughout the study period. Leucaena was highest in crude protein, Ca and Cu, and lowest in Zn and acid detergent fibre. Calliandra was highest in P, Zn and acid detergent fibre, but was lowest in K and Mg. Napier grass was highest in K and Mg, but was lowest in crude protein, Ca, P and Cu.

Except in the leucaena-napier grass mixture, where differences were not significant, establishment in shrub-grass combinations caused significant increases in the biomass yields of napier grass. Biomass yields of the woody perennials were either increased significantly or were not affected. Shrub-grass combinations did not significantly change nutrient concentrations of the legume plants. The same is true of napier grass for most nutrients except K and Mg. The former was increased significantly in combination with both legumes, while the latter was significantly reduced in combination with calliandra, but remained unchanged in combination with leucaena.

Except for K content in napier grass (r = 0.750), biomass and nutrients were not significantly correlated with rainfall. Other correlations were not significant and varied with species and parameter. It is suggested that the presence of at least some rainfall in all months maintained a reasonable level of moisture in the soil, so that adverse effects caused by prolonged drought in other areas were not observed at Maseno. Napier grass is suitable for providing the basis ration, while trees and shrubs have a significant potential as high nutrient supplements to conventional animal feeds. These can conveniently be established as tree or shrub-grass combinations. Attempts to diversify the genetic base of fodder trees and shrubs should be made to overcome problems related to toxicity, poor digestibility and the occurrence of pests and diseases.

33

MSc and MPhil theses

A preliminary quantitative survey of the insect-pest complex of some leguminous multipurpose trees in southern Nigeria

Olatoye Kehinde Oluwemimo, MSc (Agricultural Biology - Entomology), 1994

Supervisors: Dr David O Ladipo (ICRAF)

ProfJAOdebiyi

University: University of Ibadan, Oyo State, Nigeria

Abstract The four indigenous leguminous multipurpose trees, Pentaclethra macrophylla, Pterocarpus santalinoides, P. mildbraedii and Millettia thonningii are currently being screened for use as woody species component in agroforestry systems. In this study a survey of the insect pests associated with the trees species was carried out in the humid and subhumid zones of southern Nigeria, in nursery screening plots and arboretums. Two important pests were recorded on P. macrophylla. These are Anoplocnemis curvipes and termites Macrotermes sp., both of them at the two ecological zones. On P. mildbraedii there were six insect species of which five are major pests: Trigonocolus sp. and Cantatops spissus at nursery level, A. curvipes, Macrotermes and Gynandrophthalma immaculata in the arboretum.

Eight insect pests species were recorded on P. santalinoides but only Macrotermes sp. and A. curvipes were important pests. On M. thonningii eight insect species were also recorded, of which A. curvipes, Zonocerus variegatus and Macrotermes sp. were major pests.

The four legume tree species have in common two major pests, which are termites (Macrotermes sp.), and the black coreid bug (A. curvipes).

Identification of constraints and analysis of agroforestry interventions for improved livestock production of the Ejura livestock project and its environs (Ghana)

Kadwo Opoku Ageymang, MSc (Agroforestry), 1994

Supervisor: Dr James Quashie-Sam

University: University of Science and Technology, Kumasi, Ghana

Abstract Locally, the most abundant sources of animal protein are fisheries and wildlife resources. The Ghanaian government, realizing the importance of livestock as a protein source and for raw materials, has established credit mechanisms, agricultural research programmes, rural extension schemes and institutions such as the Ejura Sheep and Goats Project to provide breeding stock for farmers to boost livestock production in the country.

Although successful initially, in recent times the Ejura Sheep and Goats Project seems to be having problems. This study used the Diagnosis and Design method developed by ICRAF to identify agroforestry technology for the development of the Ejura Sheep and Goats Project.

34

MSc and MPhil theses

In this study, information was gathered from the Ejura Sheep and Goats Project farm, and ten farmers' households randomly selected from four villages and towns (Ejura, Bonyon, Duromankuma, Ehiawoanwu) which have access to assistance offered by the farm.

A questionnaire, diagnostic interviews and direct field observations were used to identify the biophysical and socioeconomic characteristics of the farm and the study area and their influence on the farming practices. The study showed the following major constraints affecting development on the farm: 1. poor soil fertility resulting from intensive system of land use 2. poor feed quality and feed shortages especially for dry season feeding, which result in high

abortion rates in farm livestock 3. lack of adequate equipment and machinery especially for preparing feed for dry season use

and lack of storage facilities for feed 4. inadequate housing particularly for large flocks 5. lack of capital for structural development 6. labour shortages and its high costs (Ghana cedi 20 000/ha cleared or weeded) have resulted in

competition between enterprises for labour especially during the peak land clearing and weeding

7. high cost of veterinary chemicals.

Among the farmers interviewed, poor soil fertility, dry season feed shortages and the poor feed quality, lack of adequate storage facilities, labour shortages and its high cost, and lack of capital for financing farm activities were the limiting factors to livestock development.

In addition to the farmers' problems, soil erosion along streams resulting in siltation and drying of the stream, poor marketing channels, seasonal price fluctuations and use of inappropriate farming practices such as high fertilizer inputs which do not meet farmers' resources were identified.

Erratic and low rainfall seriously limits forage quality and productivity. Overexploitation of wood for fuel and removal of trees during mechanised land preparation (a characteristic of commercial farming) have also affected biomass recycling and hence soil fertility rejuvenation in the area.

Although no agroforestry intervention can be proposed to solve the problems of lack of cash, inadequate equipment and machinery and labour shortages and its high cost, it is recommended that agroforestry interventions such as fodder banks, boundary planting, trees on pasture for shade, shelterbelts or windbreaks and alley farming involving cereals (maize, sorghum) and legumes (cowpea, Cajanus cajan) when properly incorporated into the system can help solve the problems of dry season feed shortages and poor soil fertility through nutrient recycling.

Interventions such as watershed protection using multipurpose trees and shrubs will reduce erosion which is found only along streams/rivers and hence their siltation. Provision of abundant quality feed which will result from the interventions proposed above will help build up disease resistance in the animals and reduce the need for veterinary drugs on the farm.

Livestock production of the Ejura Sheep and Goats farm and in the district as a whole can be improved if in addition to the agroforestry interventions recommended above, provision of cash equipment and machinery, storage facilities and formal marketing channels to check price fluctuations are made available to both the farm and the farm households.

It is also recommended that the management should be allowed to plough back some of the money they generate from sale of animals into acquisition of essential farm inputs such as veterinary chemicals and feed.

35

MSc and MPhil theses

Effect of slash-and-burn practice and Leucaena leucocephala residue management on nutrient dynamics in the humid lowlands of Ghana

Luc Andre Bayomock, MSc (Agroforestry), 1995

Supervisors: Dr SJ Quashie-Sam

Mr JGK Owusu

University: University of Science and Technology, Kumasi, Ghana

Abstract With a view to developing low-input agroforestry technology for small-scale farmers in the humid lowlands of Ghana, two experiments were conducted at the Institute of Renewable Natural Resources farm at the University of Science and Technology in Kumasi, Ghana. The purpose of the field experiment (minor rainy season, 1994) was to assess the effect of slash and burn practice as a treatment, and two treatments of Leucaena leucocephala (leucaena) residue (fresh leucaena leaves and twigs) management: 6 t/ha surface application and incorporation of 4.5 t/ha at planting followed by 1.5t/ha six weeks after planting, on soil chemical properties, maize growth, yield and nutrient uptake.

The experiment was conducted under a cut-and-carry system (plot without leucaena hedges). A randomized complete block design with four replications was used to test the treatments. Soil (0-20 cm depth profile) and maize tissue samples were collected on a three-weekly basis, and analyzed for their nutrient content. Maize height increment was measured at three-week intervals. Maize grain yield was recorded in each treatment at harvest (three months after planting).

The yield of maize in slash-and-bum practice was similar to mulching with 6 t/ha of leucaena residue. Apparently, this amount of mulch material showed no marked improvement on soil chemical properties over slash and burn practice. The uptake of nutrients by maize in slash and bum plots was superior to mulching 6 t/ha of leucaena. The benefit/cost ratio in slash and bum was similar to mulching 6 t/ha of leucaena, as a result of similar yield of maize grain that generate revenue to both systems.

The low performance recorded in mulched plots was attributed to the rate of leucaena residue applied to the soil.

To throw more light on the results obtained in the field experiment, a pot experiment was set up in the major rainy season 1995, to assess the effects of slash-and-bum practice and different rates of leucaena mulch on soil chemical properties and nutrient dynamics in maize.

A randomized complete block design was used to test the treatments imposed. Soil and maize . samples were collected on a four-weekly basis up to the tasselling and fruiting period of maize, and analyzed for their nutrient content.

The pot experiment results confirmed the superiority of slash and bum over mulching with 6 t/ha of leucaena residue with regard to soil properties and nutrient uptake by maize plants.

Mulching (91 + 3S) tp 181 + 6S) t/ha* of leucaena residue gave 59.65 to 76.42% increase in maize grain yield as compared to slash and bum. Surface application of the same quality of leucaena mulch resulted in 56.78 and 60% increases in grain yield. Observations from the pot experiment indicated that the uptake of nitrogen ranged between 46.77 and 49.42% in mulching with leucaena

36

MSc and MPhil theses

(91 + 3S) to 181 + 6 S) 6 t/ha. An increase of 17.74 to 38.48% was recorded in surface application of the same amount of mulch, as compared to the slash and burn treatment.

However, incorporation of an equivalent of 6.0 t/ha of leucaena residue in pot containing burnt Panicum ash gave 56.07% maize yield and 60.46% increase in nitrogen uptake, superior to the pot containing only burnt Panicum ash. These results from the pot experiment are very encouraging and tend to indicate that when leucaena residue is incorporated into soil in the slash-and-burn plots, the maize nutrient uptake and maize yield would increase relative to the normal slash-and-burn plots.

In formulating any recommendations of the cut-and-carry systems to farmers, however, it would be necessary to test the performance of the treatments imposed in the pots in the field. An economic study to compare the cut-and-carry, alley cropping and slash-and-burn practice would also be needed.

Evaluation of the potential of rotational tree fallows for sustaining maize production at Meatu, Shinyanga, Tanzania

Hamidou Idrissa, MSc (Agroforestry), 1995

Supervisors: Dr Luther L Lulandala

Dr Robert Otsyina (ICRAF)

University: Sokoine University of Agriculture, Morogoro, Tanzania

Abstract A study of ongoing agroforestry research at Meatu, Shinyanga, Tanzania evaluated the potential of short tree fallows on maize yields and soil fertility sustenance. The tree fallows involve three, four, and five-year old fallows, respectively cropped thrice, twice and once. In each of these tree fallows (experiments) the following three treatments were imposed: (a) maize + trees with prunnings removed, (b) maize + trees with prunnings removed with 50 kg N/kg supplement, and (c) maize + trees with prunings returned to the soil. Each treatment was replicated three times in a complete randomized design. Results of the study showed that maize yields were usually high at the opening of each experiment, given sufficient rain. In 1993 maize yield was significantly higher (P<0.05) in the four-year fallow than in the three-year fallow. In 1994 cropping season, maize yield was significantly higher (P<0.05) in treatment with prunings than in treatment with N supplement. Results from routine soil analysis showed that soil parameters did not vary significantly between treatments within experiments. However, P quantities in the topsoil were significantly different between experiments. Results from N-mineralization, for the first sampling, showed greater (P<0.05) nitrification rates under treatment with prunings than under treatment with N supplement in both three-year and five-year old fallows. At the second sampling, nitrification rates were significantly lower (P<0.05) in the three-year fallow than in the other two.

Based on the results from this study no firm conclusion can be drawn on the sustainability of the current treatments to maintain maize productivity. Nevertheless, preliminary observations indicate that the treatment with prunings seemed to be the best. Comparing the three experiments for maize yield and other soil parameters, the four-year old fallow seems better than others

37

MSc and MPhil theses

Evaluation of the effect of hedgerow intercropping using Leucaena leucocephala and fertilizer application on growth and yield of garden eggs (Solanum melongena)

Thomas FG Insaidoo, MSc (Agroforestry), 1995

Supervisor: Dr SJ Quashie-Sam

University: University of Science and Technology, Kumasi, Ghana

Abstract Field trials were conducted to investigate the effect of alley cropping local 'garden eggs' (aubergine/eggplant) with leucaena for two seasons on a sandy loam Orthi-Ferric Acrisol in Kumasi, Ghana. The local garden eggs (Solanum melongena) were grown in 4 m wide alleys between established leucaena hedgerows. The crop was subjected to three main plot and two sub­plot treatments in a split-plot design. The main-plot treatments were NPK. 15-15-15 compound fertilizer applications at 0, 180 and 360 kg/ha levels. The sub-plot treatments were mulch application at no mulch and mulched levels. The leucaena primings used as mulch material provided significant amounts of nutrients during both seasons.

The garden eggs responded very well to the NPK compound fertilizer used, since plants without fertilizer had significantly reduced rate of growth and produced very low yield which was far below potential yield levels of the crop. In the minor season (1993), the half rate (180 kg/ha) and full rate (360 kg/ha) fertilizer treatments increased the mean yield of the crop by 58 and 65% respectively and in the major (1994) season, the half and full rate fertilizer treatments increased the mean yield of the crop by 44 and 49% respectively over the 'no fertilizer' treatments. An economic analysis for the 1994 cropping indicated that it was more economical to produce the crop with the half rate fertilizer than with the full rate fertilizer.

Applying the leucaena mulch promoted growth significantly, especially in the major season. In both seasons, applying the leucaena mulch increased the mean yield of the crop by about 21% over the 'no mulch' treatments. Better yield of the crop in mulched treatments plots was in part due to the significant amount of nutrients provided by the leucaena mulch material.

By applying the half rate fertilizer plus mulch combined treatments, the mulch treatments could at least substitute for the half reduction in the fertilizer. The economic analysis for the 1994 cropping indicated that the half rate fertilizer plus mulch treatments was the most profitable, followed by the full rate fertilizer plus mulch treatments, with the 'no fertilizer plus no mulch' treatments being the least profitable and economical. Producing the crop with the 'no fertilizer plus mulch' treatments gave a substantial amount of yield and was more economical than producing it with 'no fertilizer plus no mulch'.

The results imply that producing garden eggs with leucaena mulch in alley cropping can reduce fertilizer requirement. The economic analysis in 1994 indicated that alley cropping with garden eggs is profitable and may become an attractive alternative to small-scale farmers as prices of fertilizer increases in relation to the price of the crop.

MSc and MPhil theses

Urban home gardens in Kumasi metropolis, Ashanti Region of Ghana

Theophilus Adomako, MSc (Agroforestry), 1995

Supervisors: Dr SJ Quashie-Sam

Mr JGK Owusu

University: University of Science and Technology, Kumasi, Ghana

Abstract Home gardens are a ubiquitous farming system found within the compound of individual houses and practised by households in Kumasi metropolis landscape of Ghana. However, very little is known about the home garden system in terms of classification, composition, structure, functions, management practices, or constraints to its development and promotion. This study has put together data on home gardens to assist in understanding the system and make recommendations for its management. Data was collected using a two-stage sampling procedure involving visual reconnaissance survey and detailed household survey. The reconnaissance survey was carried out to select six residential areas (suburbs) where home gardens were extensively and intensively practised. Eighty households were randomly sampled and selected in the six residential areas and detailed household surveys involving direct observation, interviews and administration of questionnaire were used to collect the data.

The questionnaire and interviews were aimed at finding the socioeconomic status of households, decision-making on gardening, components of the system, their arrangement and functions. The management practices, benefits to the gardeners, their resource/support services, and constraints facing them were also examined.

The home gardens surveyed were classified into four types: (a) agrosilvopastoral systems, (b) agrisilviculturals system, (c) mixed farming and (d) agrihorticultural systems, based on the presence of the main agroforestry components, structure and their roles.

Twenty-two different crops were observed in the study area, the major ones being Musa paradisiaca, Zea mays, Manihot esculenta, Dioscorea alata, Solarium melongena and Capsicum annuum. The animals were chicken, sheep, goat, duck, turkey, rabbit, bee, guinea fowl and fish. In addition, there were about thirty multipurpose trees and shrubs and over thirty-five ornamental plants beautifying the environs.

These tree/shrub-crop-animal (bee/fish) components were intensively integrated spatially and/or sequentially on the same land unit of individual houses. Living fence and/or non-living fence bordered some of the home gardens.

This highly diversified trees/shrubs and crops mixture in the home gardens set-up was organized into a three-layer structure: a ground layer of vegetable and tuberous crops, middle layer of relatively taller food and fruit crops, and an upper layer of tall fruit trees.

Mostly respondents and their families managed the home gardens, as well as hired labour. Household labour was the main determinant of production especially in homesteads with large families. Gardening activities were often done in leisure hours.

39

MSc and MPhil theses

Home gardens were embarked on by 86% of households primarily to reduce expenses on food budget, and 27.5% to earn extra cash from the sale of the garden produce to supplement family's incomes, as well as 58% to improve the aesthetics of the homesteads.

Households got numerous benefits such as food crops, vegetables, fruits, fodder, medicinal products, firewood, honey, spices, meat, eggs and fish which were used for subsistence and/or for sale. Some of these items were distributed to neighbours as gifts, which facilitated social ties in the neighbourhood.

The major constraints facing gardeners that agroforestry intervention can address were poor soil moisture availability in the dry season, Musa spp. (plantain/banana) lodging, crop damage by stray livestock, declining soil fertility, low livestock and poultry management for the local breeds kept on free-range basis. Inadequate extension education and services to home gardeners hindered effective promotion and development of home gardens.

Agroforestry and agricultural interventions recommended to address these constraints are windbreaks, boundary planting, living fences, proper cropping system and management, proper livestock/poultry management and fodder bank. Improved extension education and services to households practising gardening as agroforestry systems will go a long way to encourage households to manage the system effectively.

Other constraints spelt out by respondents which agroforestry intervention cannot address were insufficient time, high water costs charged by Ghana Water and Sewerage Corporation, the small size of gardens or plots, and lack of credit to finance the gardening operations.

Home gardens when promoted and developed among households in urban areas could improve the standard of living of urban dwellers in Ghana, help to minimize poverty and malnutrition, and create employment for youths as hired labour (provided with accommodation, food, clothing and monthly allowance).

Leucaena leucocephala and Gliricidia sepium supplementation of growing sheep fed rice straw: effects on feed intake, liveweight gain digestibility and rumen degradation characteristics

Martin L Kaonga, MSc (Agroforestry), 1995

Supervisors: Dr SJ Quashie-Sam Dr ELK Osafo Mr JGK Owusu

University: University of Science and Technology, Kumasi, Ghana

Abstract The evaluation of Leucaena leucocephala and Gliricidia sepium as protein supplements to low-quality diets of intensively managed small ruminant livestock was carried out in two experiments whose main objectives were: to determine the effects of leucaena and gliricidia supplementation on feed intake, liveweight gain, digestibility, and water intake by sheep, and to study the effects of two tree legumes or rumen degradation characteristics of foodstuffs.

In experiment 1, a feeding trial was conducted to study the effects of leucaena and gliricidia hay supplementation on feed intake, liveweight gain, digestibility and water intake by growing sheep.

40

MSc and MPhil theses

Thirty-six sheep were fed rice straw (50 g dry matter/kg/day) with three levels of leucaena and gliricidia (7, 14, and 21g dry matter/kg body mass (M0.75/day) in a completely randomized block design in a factorial experiment.

Increases in level of leucaena and gliricidia supplementation significantly (p< 0.05) increased; foliage protection supplement and total feed dry matter intake, foliage protein supplement and total feed dry matter intake per metabolic size and protein supplement intake at week 1. However, Multipurpose trees supplementation did not significantly (P<0.05) affect rice straw DM intake. The type of multipurpose trees and multipurpose trees X level interaction did not significantly (p<0.05) affect feed intake.

The average daily liveweight gain was significantly (p<0.05) higher in sheep offered leucaena than gliricidia. MPT x level interactions were significant (p<0.05) for average daily liveweight gain and metabolic size of sheep at week 10. Levels 21 of leucaena and 14 of gliricidia had higher and significant average daily liveweight gain of 15 g and 2 g/day respectively.

In vivo organic matter digestibility differed significantly (p<0.05) according to type, level or type and level of multipurpose trees supplementation. There were no significant (p< 0.05) variations in water intake due to supplementation.

In experiment II, the effects of leucaena and gliricidia hay supplementation on in sacco degradability and in vitro gas production of foodstuffs were studied. Three sheep were fed rice straw (50 g dry matter/kg liveweight/day) with 14 g dry matter/kgM /day of supplement in a completely randomized design replicated three times. Rumen NH3 -N and pH concentrations were determined during 12 hour duration.

There were no significant (p< 0.05) variations in the sacco degradability constants a, b, c and nutritive index value due to type of multipurpose trees offered. Significant (p<0.05) differences existed between different components of rice straw in the following order: rice straw > leaf > whole.

The in vitro gas production constants a, b, c and nutritive index value were significantly (p<0.05) higher in leucaena than gliricidia supplementation. The mean volume of gas produced by rice straw significantly (p < 0.05) differed according to fraction in the following order: rice straw stem > leaf > stem. The in vitro gas production of leucaena and gliricidia were significant (p < 0.05) but low. They were comparable to rice straw stem. Sheep on leucaena had significantly (p < 0.05) higher rumen NH3 -N and pH concentration than those on gliricidia supplementation. The correlation between in sacco degradability and in vitro gas production were poor. The'results indicate that dry matter intake, digestible dry matter intake and rumen degradability of rice straw and liveweight gain on Djallonke x Sahelian x sheep fed rice straw could be increased by supplementation with leucaena and gliricidia hay.

The influence of socioeconomic factors on the promotion and adoption of agroforestry technologies based on the traditional ngitiri system

Halifa BA Msangi, MSc (Environmental Forestry), 1995

Supervisors: Dr John Hall Dr Marlene Buchy Dr Robert Otsyina (ICRAF)

41

MSc and MPhil theses

University: University College of North Wales, Bangor, UK

Abstract This study surveyed the Sukumaland (Tanzania) ngitiri fodder conservation system to analyze and document socioeconomic factors and their influence on the ngitiri system's promotion and adoption. Ngitiri is a traditional system used by the Wasukuma people of western Tanzania to conserve fodder for dry season use. Basically it involves the selection, fencing and enrichment of parts of the grazing land. Attention is given to land availability, security of tenure, labour use, and availability and gender issues (with particular reference to the responsibilities of women). Farmers' attitudes to, and perceptions of, potentials/limitations of improvements of the system were determined.

Field work involved three divisions in Shinyanga District. Formal and informal interviews of eighty farmers in ten villages were carried out. Qualitative and quantitative information was collected and summarized as frequently distributed and by cross-tabulations.

The study confirms that ngitiri is a valuable system for fodder production and land conservation. Farmers would like the system to be revived and improved to provide opportunities for the development of adaptable agroforestry methods and to arrest the rapid land degradation trends.

Generally, the ngiriti system offers prospects for future use in the management of natural resources and could be a rewarding economic venture. However, the variation of land holding among farmers, coupled with the absence of clearly defined land ownership, and insecurity of tenure and land scarcity, were identified as limiting ngitiri establishment and development.

The study concludes that facilitation of land ownership, tenure rights and re-empowering of local or customary institutions to manage their resources will enhance the promotion of ngitiri system and boost its sustainability.

Influence of some multipurpose tree species on soil fertility

David O Oke, MSc (Agroforestry), 1995

Supervisor: Prof Olatunji Kadeba

University: Federal University of Technology, Akure, Nigeria

Abstract This study was carried out to investigate the effect of Acacia crassicarpa, Gliricidia sepium, Dalbergia latifolia and Leucaena leucocephala on the nutrient status of soil under them. Soil samples from the plot supporting each of the multipurpose trees were analyzed and soil parameters such as texture, pH, organic matter content, phosphorus, exchangeable calcium, magnesium and potassium were determined. Greenhouse experiments were conducted to determine the effects of leaf litter of the multipurpose trees on soil fertility using maize as the test crop.

The multipurpose trees had a depleting effect on the potassium, phosphorus and magnesium content of the soils under them. Nitrogen concentrations in soil from the multipurpose tree plots were not significantly different from that of control plot.

Acacia crassicarpa and Dalbergia latifolia leaf litter inhibited maize growth at first planting leading to growth reductions of 42% and 39% respectively relative to the control. Leucaena

42

MSc and MPhil theses

leucocephala and Gliricidia sepium on the other hand increased shoot dry weight of maize by 9% and 16% respectively.

Significant improvement in fertility of soil supporting each of the multipurpose trees was observed after incorporation of leaf litter of respective tree species especially that of Gliricidia sepium and Leucaena leucocephala. Gliricidia and Leucaena litter increased shoot dry weight of maize by 60% and 49% respectively, compared with control.

Evaluation of indigenous fodder trees and shrubs in different agro-ecological zones of western Kenya

Mary Anette, MSc (Agroforestry), 1996

Supervisors: Prof Dr Ralph Gretmacher

Dr Robert Paterson (ICRAF)

University: University of Agriculture, Vienna, Austria

Abstract Indigenous trees and shrubs can help to overcome the periodic fodder shortage in western Kenya, East Africa. Literature gives little information on indigenous trees and shrubs used as a source of fodder in this area. The aim of this study, therefore, was to identify indigenous fodder trees and shrubs eaten by cows and goats in different agro-ecological zones of western Kenya and explore their importance and popularity. The study is based on observation of farmers during February and July 1995. Different demographic and ecological factors influence the farming systems in western Kenya. Differences in growing species, in the plant arrangements, and the preferences of farmers were observed in the zones. In total, eight different trees and shrubs (Bridelia micrantha, Carissa edulis, Grewia trichocarpa, Harrisonia abyssinica, Lantana camara, Rhus natalensis, Sesbania sesban and Tithonia diversifolia) were identified as the most important fodder species for livestock. The results of these species are described in this report and listed in tables.

The palatability of indigenous trees and shrubs eaten by livestock was explored as it was the most important criterion farmers used to evaluate their fodder species. Other criteria such as growth, drought resistance, diseases/pests were also investigated and compared.

Potential use of Calliandra calothyrsus hedges with napier grass (Pennisetum purpureum) for soil erosion control in a high potential area of Embu, Kenya

Samson Danford Angima, MSc (Appropriate Technology), 1996

Supervisors: Dr Asenath Omwega

Dr Mick O'Neill (ICRAF)

University: Kenyatta University, Kenya

Abstract

The potential of contour Calliandra calothyrsus hedges in combination with napier grass (Pennisetum purpureum) hedges, in controlling runoff and soil loss from a cropped field was

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MSc and MPhil theses

studied during two cropping seasons in a Nitisol soil under semi-humid conditions at the National Agroforestry Research Project-Embu, Eastern Province, Kenya. The experiment had eight runoff plots measuring 5 x 30 m, on an 18% slope, and was conducted in a randomized complete block design with two replicates and four treatments: (1)control of maize only, (2) grass hedge of Pennisetum purpureum, (3) tree hedge of Calliandra calothyrsus and (4) combination hedge of Pennisetum purpureum and Calliandra calothyrsus. Maize and bean intercrops were planted during the first season (short rains), and maize monocrop in the second season (long rains). Soil and water runoff losses after each major rainfall event and the changes in the crop cover as well as total dry matter from the two fodder types were measured. Topographic surveys of the experimental plots were made at the end of each cropping season. Rainfall intensity and changes in infiltration rates and bulk density along the hedges were also determined.

Soil losses from the plots with hedges were lower than the control, though not significantly. Over the two seasons, the average cumulative soil losses from plots with tree hedge and combination hedge were 71% lower than that of the control plot, while grass hedge plots were higher than the control by 14%. On the other hand, water runoff losses from tree hedge, combination hedge and grass hedge plots were 50%, 70% and 96%, respectively, lower than that of the control plot, although not significant (p=0.9). In both the short rains and long rains seasons, there were no significant differences between the treatments in either runoff or soil loss. Likewise, 'least significant difference' carried out on the treatment means for runoff and soil loss showed no significant difference among treatments. It was concluded that the effect of the hedges at this stage had not become significant in reducing runoff or soil loss.

Soil bulk density did not change while infiltration rates at the end of the experiment along the hedges were slightly higher than in the beginning of the experiment. Percentage average decrease in slope followed this order: combination hedge >tree hedge>grass hedge with 1.83%, 1.77% and 1.74% respectively, while the control plot had a 0.67% increase in slope angle. Total dry matter in the two lines of hedge was 12 t/ha/year of napier for the grass hedge and nearly 8 t/ha/year of napier from the single line of rapier in the combination hedge. The fodder harvested from the tree hedge averaged 2 t/ha/year and 0.8 t/ha/year of stems, while the combination hedge produced 0.7 t/ha/year of fodder from the tree hedge and 0.3 t/ha/year of stems. This indicates some extra benefits for use of hedges for soil conservation, compared to mechanical earth structures.

Agroforestry adoption by small-scale farmers: a case study of pioneer tobacco company's agroforestry programme

Francis Dontoh Cobbinah, MSc (Agroforestry), 1996

Supervisor: Dr SJ Quashie-Sam

University: University of Science and Technology, Kumasi, Ghana

Abstract Access to and control of resources by households affects their interest in and adoption of effective land use methods, which may enhance natural resource development, and expansion of households production capacities. The analysis of the resource base of households thus becomes imperative in an attempt to introduce any innovation to a group of people.

The Pioneer Tobacco Company in Ghana is tring to introduce and support an agroforestry programme in tobacco farming areas. This study was undertaken to better understand factors that influence farmers' acceptance and adoption of the company's agroforestry programme. This was

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done by using a questionnaire guide to interview sixty households randomly selected from each of four districts covered by the programme. The households selected were categorized into tree farmers and non-tree farmers or households. Simple statistical techniques including the use of frequency distribution tables, means, standard deviation and percentages were employed.

The study revealed that interest in and adoption of the tree planting exercise was dependent on the objectives of households, principally food and cash, their control over resources such as land, labour and credit, and managerial ability. On the whole, households which had planted or were planting trees owned almost all the land they cultivated or had access to large tracts of land averaging 21.76 acres, relatively high annual incomes of Ghana cedi 411 670, large household size of about 12 members, and more males than households which have not planted trees. Tree species cultivated include Leucaena leucocephala, Senna siamea, Anacardium occidentale and Gmelina arborea. Most farmers cultivating trees also grew tobacco, which was purchased by the Pioneer Tobacco Company at reasonably high and stable prices. The predominant farming system was bush and grass fallowing. Farmers maintained about three different plots of land totalling about three acres.

Adoption rate had been quite high in the communities (53%) but relatively low among tobacco farmers (43%). The Pioneer Tobacco Company was continuously sustaining the programme and making it more farmer-centred by responding quickly and addressing the perceived needs of farmers including excessive weed growth.

The effect of Leucaena leucocephala mulch on the growth and yield of irrigated tomato (Lycopersicon esculentus Mill.)

Simon A Kafari, MSc (Agroforestry), 1996

Supervisor: Dr SJ Quashie-Sam

University: University of Science and Technology, Kumasi, Ghana

Abstract A study was conducted at Akumadan vegetable irrigation project in the Ashanti region of Ghana from 12 December 1994 to 7 April 1995, to evaluate the effect of Leucaena leucocephala mulch on yield and yield components of irrigated tomatoes, to assess the fertilizer replacement potential of leucaena mulch, and to determine from the treatments the most economic alternative for tomato production.

The results showed that leucaena mulch has a significant effect on the growth and development, fruit set, fruit weight, reproductive efficiency and fruit quality of tomatoes. Leucaena mulch also showed significant effect on weed control, soil moisture content and soil bulk density but not on soil chemical properties. Along with these were significant effects shown by fertilizer/mulch combination and by fertilizer alone. In general, leucaena mulch showed a high fertilizer replacement potential, better exploited at mulch levels of 10 tons/ha fresh mulch. At 10 tons/ha mulch level combined with 50 kg N/ha, yields were as economic as applying fertilizer alone at a high rate of 150 kg N/ha. No extra rewards were gained by increasing fertilizer rates to 100 kg N/ha combined with 10 tons/ha mulch. Using the 1995 production figures, profitability margins were higher with a high supplementation of chemical fertilizer with mulch, with 10 tons/ha mulch combined with 150 kg N/ha giving the highest benefit/cost ratio.

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Rooting characteristics and inorganic nitrogen distribution in three land-use systems on an Oxisol in western Kenya

Kindu Mekonnen, MSc (Forestry), 1996

Supervisors: Dr Erick Koech

Dr James Kiyiapi

University: Moi University, Eldoret, Kenya

Abstract In western Kenya, intensive cropping and leaching losses of nutrients have reduced soil fertility and led to low crop yield. As a remedial measure, farmers in the area leave parts of their land fallow. Weeds and Sesbania sesban are prominent in the fallow. It has been speculated that planted tree fallows reduce leaching losses and pump up nutrients from the subsoil, but little has been studied on these processes. Since understanding of rooting characteristics is essential in this context, a field study was conducted on a Kanduifalfic Eutrudox soil to compare relationships between rooting patterns and soil nitrogen in planted sesbania fallow, natural fallow, and maize systems. Two root measurement techniques (profile wall and soil monolith) were used. For the profile wall, a trench was dug in each replicate of the three land-use systems; the surface of the wall was then smoothed, sprayed with water and forked to expose roots. A transparent polythene sheet marked with 15 cm x 15 cm grids was laced against the profile wall to map the total number of exposed roots in each grid. For the monolith technique, soil from the profile wall, to the depth of rooting, was collected from 15 cm x 15 cm grids with a metal sampler (volume = 2250 cm ). From each soil sample, 100-200 g was sampled for gravimetric water content, ammonium and nitrate determination. The remaining soil of each sample was soaked overnight, washed and then roots were separated from debris and sorted by plant species. Root length, root diameter and dry weight of maize, weeds and sesbania were determined. Square root transformation for root data and logarithm transformation for inorganic-N data were used and both data statistically analyzed by SAS (Version 6.10).

Root tip counts indicated a rooting depth of 120 cm in maize system, 240 cm in weed fallow, and greater than 405 cm in sesbania fallow. Root length (cm/cm ) at 0-120 cm was greater (<0.05) for weed fallow than maize and sesbania. On the other hand, root length at 120-240 cm was higher for sesbania (8.0 cm/cm2) than weed fallow (5.5 cm/cm2). High root length in the topsoil of weed fallow was attributed to a greater percentage of fine roots. In turn, fine roots in weed fallow were greater due to the abundance of grasses such as Digitaria abyssinica and Paspalum scrobiculatum. Root dry weight in sesbania and weed fallows and maize systems was high (> 60% of total) in the 0-30 cm soil depth as compared to lower soil profile, indicating the concentration of roots in the topsoil. Total plant biomass was 50.4t/ha for sesbania, 9.6 t/ha for weeds and 4.7 t/ha for maize. At 0-120 cm, nitrate-N in weed and sesbania fallows was lower (P< 0.05) than the nitrate-N content in the maize system, suggesting lower uptake due to less root length density and/or less demand for N by maize than sesbania and weeds. At 120-240 cm, nitrate-N was higher in weed fallow (22 kg/ha) than sesbania fallow (10 kg/ha). Ammonium-N in the soil profile, in contrast to nitrate-N, was not affected by the land-use system.

Sesbania roots were able to penetrate deeper into the soil profile (> 405 cm) and produced higher below as well as aboveground biomass. Therefore, rotating maize with sesbania can help utilize nitrate-N that might be leached to below the maize-rooting zone.

MSc and MPhil theses

Women and agroforestry in Kabale District, Uganda: an exploratory study of social issues affecting women's agroforestry behaviours and production

Lesley) Just, MSc (Rural Economy), 1996

Supervisors: Dr Eloise C Murray Dr William Phillips Dr Karen Hughes

University: University of Alberta, Edmonton, Canada

Abstract Africa is plagued by problems of deforestation and environmental decay. The International Centre for Research in Agroforestry (ICRAF) is researching the potential of agroforestry as a solution to some of these problems. This study was designed to explore and identify the issues that affect women farmers in Uganda and affect their agroforestry behaviour.

Thirty two women from Kabale District were interviewed about women's roles in Bakiga culture, responsibilities and expectations placed upon women farmers, issues affecting women farmers, rights and access to land and trees, and changes in women's lives over time. Six general themes emerged from the interviews that were reported as factors that influenced women's land-use decisions and actions. The themes were identified as (1) land and tree tenure, (2) population pressure and land availability, (3) alcoholism and family violence, (4) AIDS-related illness and death, (5) household demands and women's resources and (6) female community solidarity. Five of the women were chosen as case study participants and detailed life history information was collected from them to illustrate how the themes manifest themselves in practice.

The information collected during the course of the study was integrated into a human ecological framework. Women's triple roles of reproduction, production and community maintenance work, together with the social manifestation of gender, were considered to create a theoretical model of the interaction between rural women's lives and agroforestry systems. The model shows that agroforestry is not only a biophysical farming system. There is a human component in agroforestry systems that fluidly interacts with other components to determine, in part, the end product of the agroforestry system.

The study concluded that not all rural Ugandan women are unempowered victims of circumstance. Rather, many women have some degree of control over their labour and resources, and are in a position of decision-making control over the land they cultivate. Agroforestry programs need to be designed that work in conjunction with the current circumstances of Bakiga women. Furthermore, collaborative research and development programs are needed to address issues that directly and indirectly affect agroforestry production.

Propagation of Uapaca kirklana using tissue culture techniques

Moses FA Maliro, MSc (Agroforestry), 1996

Supervisors: Dr Moses BKwapata Prof Jumanne A Maghembe (ICRAF) Prof Vincent Saka DrWABMsuki

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MSc and MPhil theses

University: University of Malawi, Bunds College of Agriculture

Abstract A study of propagation of Uapaca kirkiana using tissue culture techniques was done at Bunda College of Agriculture. Experiments were conducted on in vitro and in vivo seed germination; auxiliary shoot proliferation using seedling stem nodal sections; direct organogenesis and callus development from stem shoot sections, adult tree leaf and cotyledonous explants; and root developments. Explants were fruits obtained from a local market, some fruits direct from trees, and adult tree explants were obtained from Uapaca kirkiana provenance near the College.

Treatments in the seed germination experiments included surface sterilization of seeds with four different concentrations of sodium hypochlorite (NaOCI) and four exposure times; primary and secondary seed-coat removal; split-plot treatments of two fruit sources (market and direct from trees) as main factors, and two seed germination media — Murashige & Skoog (MS) and Woody Plant Medium (WPM) and subplot factors. Another germination experiment was set up in a greenhouse with the two fruit sources as main factors and primary seed-coat removal and non-removal as sub-factors.

The auxiliary shoot proliferation experiment used seedling stem nodal sections as explants. Treatments included 0, 5,10,20,40, 80 and 160 mg/1 of kinetin growth regulator supplement on WPM media in a preliminary test. A detailed experiment followed with a split-plot design which included five indole butyric acid (IBA) levels (0.0, 0.25,0.50,1.00, 2.00 mg/1) as main factors and the same levels of kinetin as sub-factors. The direct organogenesis and callus experiments tested three types of tree organs which included adult stem shoot sections, leaf sections and cotyledonous leaf sections. MS basal salts media were supplemented with 2 mg/1 IAA+2 mg/ kinetin+10 mg/1 inositol and White vitamins and glycine+80 mg/1 adenine sulphate+10 mg/1 tyrosine for direct organogenesis; and 2 mg/1 IAA + 0.5 mg/1 kinetin for callus development.

Explants for rooting experiment were obtained from auxiliary shoot proliferation plantlets and tested on rooting media in a split-plot design. The main factors were two basal salts (MS and WPM) and subfactors were five IBA growth regulator levels (0.0 IBA, 0.5 IBA, 0.5 IBA+ 0.5 NAA + 0.5 BAP, 1.0 IBA and 2.0 IBA in mg/L) The containers used for media were 25 mm x 150 mm bellico tubes with 20 ml quantities. Each treatment had N= 20 cultures.

Incubation of cultures was done under 16 hours light illumination at45uEM /s except for callus cultures which were incubated under 24 hour darkness. Temperatures were maintained at 25-28 C The data collected was subjected to analysis of variance and regression analysis where necessary.

Optimum concentration of NaOCI for surface sterilization for U. kirkiana seeds was 20% for 20 minutes. Removal of both primary and secondary seed-coats promoted the number of aseptic seedlings. The MS medium gave significantly higher frequency of normal seedlings (90%) and multiple seedlings/seed (90%) than WPM medium in the first experiment. When the experiment was repeated the effect of the two media did not significantly differ. Primary seed-coat removal improved in vivo germination from 55% to 78% and from 35% to 95% for market fruits and fruits direct from trees respectively. The seeds exhibited apomixis with a minimum of 9 seedlings/seeds for in vitro, and 2 seedlings/seed for in vivo germination.

The high number of shoots that develop per auxiliary nodal bud section was achieved with supplementation of 0.05 mg/1 kinetin alone (1.3 shoots) or combined with 0.25 mg/1 IBA (1.1 shoots), 2.0 mg/1 kinetic alone (1.1 shoots) or combined with 0.5 mg/1 IBA (1.3 shoots).

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MSc and MPhil theses

The direct organogenesis and callous cultures did not regenerate into adventitious plantlets but just developed callus and embryos. The stem sections had a high callus development frequency (67.5% partial and 15% full) followed by cotyledonous sections (27.5% partial and 20% full). Adult tree leaf explant callus development failed because all cultures had fungal contamination. The subcultured calli proliferated fastest on WPM supplemented with 3.0 mg/1 IAA. Higher ratios of kinetin to auxin (IAA) slowed calli proliferation. In the rooting experiments, MS media containing 1.0 and 2.0 mg/1 IBA promoted rooting at 65% (1.7 roots/plantlet) and 60% (1.3 roots/plantlets) respectively, than lower levels of IBA The MS media promoted better rooting (0.7 roots/plantlets) than the WPM media (0.4 roots/plantlet).

Further investigation on media protocols to improve adventitious auxiliary shoot proliferation and rooting performance to ensure high field survival of U. kirkiana plantlets is suggested. Chemical names used: 6-furfurylaminopurine (kinetin); benzyladenine (BA); N6-benzylaminopurine (BAP); 1 H-indole-3butyric acid (IBA); 2-naphthaleneacetic acid (NAA); indole -3-acetic acid (IAA); and gibberellic acid (GA3).

Constraints and solutions to small-scale tree nursery management in the coffee based land-use systems of Murang'a District, Central Highlands, Kenya

Niall O'Connor, MSc (Agric. Science), 1996

Supervisors: Professor John J Gardiner

Professor Maarten Nieuwenhuis

University: University College, Dublin, Ireland

Abstract

It is commonly accepted that as populations increase, the resulting pressures on land for cultivation mean that trees are cleared for cash or food crops. Observations have shown that in Murang'a district, trees — cultivated and managed — have in fact assumed an important place as one of the many smallholder land-use options. Throughout Murang'a District, however, it was observed that farmers relied upon one species, Grevillea robusta, to fulfil all the roles that they required from the forestry segment of an agroforestry system. Few alternative multipurpose tree species were available from nurseries and furthermore, farmers did not know how to manage or benefit from these species. The study area (Murang'a District, Central Highlands, Kenya) covers many agro-ecological zones, which replicate the social and ecological conditions found in many of the east African highland areas. The need for a variety of a multipurpose tree species in these areas is well documented. To alleviate many of the problems facing the rural population, such as fuelwood shortages, soil erosion and decreasing soil fertility, emphasis must be placed on using multipurpose tree species in agroforestry systems. The ability to supply these trees is an important responsibility of the many small-scale nurseries located throughout Murang'a.

The study surveyed small-scale tree nurseries. Results highlighted many of the constraints associated with the management of a nursery, both from a silvicultural and practical point of view. In particular, tree seed and seedling management, water availability, ownership and objectives, production capacity and external influences are discussed.

Recommendations are made on how to further develop nurseries and their capacity to supply the trees needed to develop successful agroforestry systems. The principal recommendations include

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MSc and MPhil theses

establishing greater communication links, re-organizing the extension services, and encouraging external organizations to redirect their inputs and to cease the free issue of seedlings.

An assessment of traditional agroforestry systems in Arua District, Uganda

Gift Okojjia, MSc (Agroforestry), 1996

Supervisors: Dr John Kaboggoza

Dr Don Peden (ICRAF)

University: Makerere University, Kampala, Uganda

Abstract The main aim of the study was to assess traditional agroforestry systems in Arua district. The specific objectives were (a) to assess the effect of household characteristics and requirements on tree/shrub products and services, (b) to assess the role of extension service on the tree/shrub use and adoption of modern agroforestry practices, (c) to record farmers' preferred tree/shrub species for various uses, (d) to examine the issues related to gender and existing rights to use of trees and shrubs, (e) to identify endangered tree/shrub species, (f) to assess how the tree growing systems, agriculture (crop husbandry), soil erosion and conservation, and livestock components influence one another in the traditional agroforestry systems. For the field survey 165 smallholder farmers throughout the whole district were interviewed.

The major results were: The average family size was seven people per household, which was headed by husbands mainly aged 30-64 years. Most household heads were lowly educated up to primary school level, worked full-time on their farms, and had no other occupations. Most of them lived in grass thatched mud-and-wattle huts, had customary land tenure and owned 1-10 ha of land per family but they faced only limited land disputes.

The households relied heavily on indigenous knowledge to manage their traditional agroforestry systems, restricted mainly to growing fruit trees and trees for wood and poles near homesteads, and randomly scattered trees in croplands. Being subsistence farmers, their main source of energy was firewood, which they got mostly from communal natural woodlands.

Most families did not grow trees/shrubs specifically for fodder or soil/environmental improvement. Only farmers in 14.5% of the households had ever attended any training in agroforestry, while the extension visits covered farmers in 9.6-26.1% of the households. The purpose of the extension visits was basically to give technical advice. The limited extension service contributed to continued uses of local knowledge to manage traditional agroforestry systems in the district.

Trees/shrubs which the farmers, preferred to grow on their farmlands were those that provided wood products, followed by fruit trees. There was little preference for growing tree/shrubs for fodder, environmental protection/ornamental and medicinal uses.

Responsibility and rights for planting and using trees/shrubs were mostly held by the household heads/husbands, followed by sons, other relatives, wives, daughter and lastly other non-relatives.

Twelve trees/shrubs were identified as endangered/threatened.

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MSc and MPhil theses

The main conclusions were that: Most fanners in the district practised subsistence agriculture and traditional agroforestry systems. The main traditional agroforestry systems were agrisilvicultural systems for wood production and food production in the cassava-cereals-tobacco zone at subsistence level of production. Traditional agroforestry systems consisted of trees/shrubs randomly scattered in croplands, and fruit trees and shade trees in the homesteads. Apart from bananas, agricultural crops consisted of annual crops, hence there was no close interaction between tree components and annual crops. Sheet erosion is the commonest form of soil erosion. Soil conservation structures and cultural erosion prevention measures were not used on large scale.

The livestock component is very low, as such, fodder trees and cut-and-carry method of raising stall-fed livestock were absent.

• the main recommendations were that government ministries/departments responsible for agriculture, forestry and local government, non-government organizations and religious-organizations should:

• form an integrated team of extension staff and community development workers to establish agroforestry demonstration centres/plots at on-farm sites within various religious and administrative parishes

• facilitate introduction of improved breeds of cattle for stall-feeding/zero grazing which was almost nonexistent during the study period

• organize more training, seminars and workshops to train the people in sustainable agriculture and agroforestry systems

• agroforestry extension efforts are concentrated on trees/shrubs that farmers preferred to grow more and those that on demand are deficient supply: for poles/fuelwood, and fruit production.

• the numbers of extension field staff be increased and they be trained in basic principles and practices of agroforestry techniques suitable to the study area, to raise their effectiveness and efficiency

• adult literacy classes be integrated into the overall rural development • farmers be exempted from paying taxes on trees/shrubs they have planted or protected on their

farmlands • more detailed study be carried out on Melia azadirach to improve on its termite resistance,

fodder quality and upper-storey characteristics, and Tithonia diversifolia for its soil improvement qualities

• research be carried out to determine the quantity of beans consumed in refugee camps and settlement.

Evaluation of incentive packages to farmers for tree planting: a case study of Ashanti Region of Ghana

Isaac Kwasi Asante, MSc (Agroforestry), 1996

Supervisor: Dr SJ Quashie-Sam

University: University of Science and Technology, Kumasi, Ghana

Abstract Rural dwellers rely on forest resources for their livelihood. However, population pressure, poor farming practices and indiscriminate felling of trees have resulted in forest resource depletion and degradation. Tree planting by rural people has been recognized as one of the measures to reverse

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MSc and MPhil theses

this situation. Nevertheless, rural people are resource poor and for that reason need to be assisted and/or encouraged by incentive packages to adopt tree planting.

This study was undertaken in forty communities from eight districts in the Ashanti Region of Ghana, to identify organizations that provide incentives, the items they provide, and the recipients of the packages through field observations, household interviews, participatory rural appraisal techniques and from secondary data sources.

An important aspect of the study was the examination of beliefs, perception and attitudes of farmers on incentive packages on tree planting.

A number of factors were identified to affect tree planting and its success. Among these were socioeconomic variables such as education, income, perception of farmers, commitment on the part of adopter, expected benefits and tenure. Results of the study revealed that on the average, most farmers do not get access to incentive packages like working tools, food, cash and insecticides. Farmers prefer cash in the form of credit and/or grants to other items such as food, seeds/seedlings, working tools, insecticides. Incentive packages motivate farmers in tree planting. Finally, tree planting and conservation projects must carry with them financial gains and input supply schemes to realize the success required.

Adoption and farmer perception of agroforestry practices by low resource farmers — a case study of Malawi

Paulanco Howard Thangata, MSc (Agroforestry), 1996

Supervisors: Dr John Blyth

Prof Jumanne Maghembe (ICRAF)

University: University of Edinburgh, UK

Abstract More effective integration of indigenous knowledge and perspectives into the development of agroforestry technology is increasingly becoming a norm. This is the result of a need to better target research, ethical concerns about participation and power and the recognition that indigenous knowledge is a potential tool that may often be complementary to scientific knowledge. Farmer participation in research planning and implementation is a form of collaboration between researchers and farmers. This helps in unearthing farmers' real problems and needs. Knowledge held by farmers can provide a resource for science irrespective of their participation in the use of that knowledge.

In Malawi, agroforestry is being seen as the only way to improve soil fertility, to sustainably produce enough to feed the growing population. Arable land is decreasing drastically and the environment is degrading rapidly.

In an attempt to raise crop production in the Domasi Valley in Zomba Rural Development Project, ICRAF has embarked on technology transfer by working in close collaboration with farmers. On-farm research by farmers is the most effective way to convince farmers to plant trees. Field tours are also effective training methods. Farmers learn by seeing and doing. During this survey it was found that the major problem is lack of fertilizer. Since most small-scale farmers have no

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MSc and MPhil theses

resources to purchase farm inputs, agroforestry although labour intensive, might be a best option for them.

The other problem in Malawi is the lack of extension messages for agroforestry, hence the need to train both farmers and extension workers under conducive government policies. Training for farmers through participation in village nurseries increases local community sufficiency and reduces the need for continued technical assistance from the government or project.

Researchers have to be aware that on-farm testing does not imply adoption of a technology. The adoptability of a new agroforestry practice is determined by the farmers' resource base, degree of market integration, cultural preferences and perceived benefits.

Typologie et dynamique des peuplements arborgs du bas-glacis de Bondoukuy, ouest du Burkina Faso

Aii Mahamane, MSc (Biologie et Ecologie Vegetales), 1996

Supervisor: Prof. Guinko Sita

University Universite de Ouagadougou, Burkina Faso

Resume La region de Bondoukuy est situee dans le sud ouest du Burkina Faso (3 45 et 11 51) dans le secteur sud soudanien (Fontes et Guinko, 1995). La pluviosite annuelle est de 847 mm repartis sur 5 a 6 mois. Elle permet la pratique de cultures cerealieres comportant une rotation avec le coton, sous un pare arbore ou arbustif. L'etude de la typologie et de la dynamique des peuplements arbores du bas-glacis, a pour objectif la caracterisation de la regeneration des populations des differentes espe'ces des pares agroforestiers.

L'etude est basee sur des observations a l'echelle des champs et sur des entretiens avec les paysans. Une typologie des peuplements arbores a d'abord ete realises a partir de photographies aeriennes. Celle-ci a abouti a la definition de dix unites paysageres que ont servi de base pour la caracterisation du peuplement arbore au sol. En fonction de la dominance d'une ou de deux espeees, cinq types principaux de pares ont ete definis, caracterises par un ou plusieurs facies de pare. II s'agit des pares a Parkia biglobosa (nere) et Butyrospermum paradoxum (karite), des pares a dominance exclusive de B. paradoxum, des pares a B. paradoxum et Bombax costatum, des pares a B. paradoxum et Pterocarpus erinaceus, des pares a B. paradoxum et Burkea africana. Par ailleurs, le recouvrement arbustif ou arbore par strate a permis de classer chaque facies en pare arbustif ou arbor6, bas ou haut.

De Panalyse de la structure des populations des espeees par facies, il se degage d'une facon generate une classe d'age qui domine les autres, entre 75 et 150 cm pour le karite, qui correspond aux individus qui produisent le maximum de fruits. La structure des populations des espeees prend ainsi une allure en cloche, de tendance equienne. Dans le contexte d'une culture itinerante, cette structure peut avoir une allure bimodale, refletant la presence de plusieurs generations. Lorsque la culture se perennise sur le champ, le peuplement arbore maintenu se developpe, mais vieillit. La comparaison du nombre d'especes maintenues dans le pare a celui de la regeneration potentielle et des savanes a sols draines suggere que les paysans n'exploitent, environ, que la moitie de la biodiversite. Par contre, le pare represente une forme d'optimisation de celle-ci des lors que les productions sont relativement meilleures que celles de la simple cueillette. Les produits sont representes par les noix du karite, les gousses du nere, les feuilles, les ecorces, le fourrage, etc.

MSc and MPhil theses

Avec la pression demographique actuelle sans cesse croissante le niveau de la regeneration de beaucoup d'especes connaitra une diminution, ceci se traduira par une eclaircie du pare et une variation de la physionomie actuelle de certains fades et particulierement ceux a P. biglobosa.

Evaluation of multipurpose shrub legumes for use as nitrogen supplements in maize stover based diets for growing goats

Florence V Nherera, MSc (Animal Science), 1996

Supervisors: Dr Lindela R Ndlovu

Dr Ben Dzowela (ICRAF)

U niversity: University of Zimbabwe

Abstract Leguminous tree and shrub forage can improve livestock performance in tropical regions where feed selection is limited and quality is often poor. However, the occurrence of polyphenols in some leguminous browse forage plants may have adverse effects on production. Three psyllid resistant leucaena species (Leucaena esculenta ssp. paniculata, L. diversifolia ssp. stenocarpa and L. pallida), Calliandra calothyrsus and Acacia angustissima were evaluated as potential nitrogen supplements for growing goats fed unlimited maize (Zea mays) stover based on chemical analysis, in vivo digestibility and a growth trial. Leucaena esculenta forage had the highest (PO.001) content of nitrogen (38.3 g/kg dry matter) compared with L. diversifolia, L. pallida and C. calothyrsus, with 36.3, 34.8 and 34.0 g/kg dry matter respectively. The content of insoluble proanthocyanidins was highest (P<0.001) in C. calothyrsus forage, moderate in L. esculenta and L. diversifolia and lowest (P<O.001) in L. pallida. The goats given L. esculenta and L. pallida-supplemented diets recorded higher (P<-.05) total dry matter intake than those on L. diversifolia and C. calothyrsus during the digestion trial. In the growth trial, total dry matter intake was highest (PO.05) in goats on the L. pallida and C. calothyrsus-supplemented diets.

Growth rate during the last five weeks of the study was highest (P<0.001) for goats on the C. calothyrsus supplement (44.2 g/day), reflecting a high nitrogen use efficiency, while those given the L. esculenta supplement achieved a rate of gain of 27.5 g/day and those supplemented with L. diversifolia and L. pallida gained 37.8 and 40.6 g/day, respectively. Acacia angustissima proved to be toxic to the goats. The mean apparent digestibility coefficients of nitrogen for the diets supplemented with C. calothyrsus, L. diversifolia and L. pallida was 0.56 and differed significantly (P<0.001) from that reported for goats on the supplement L. esculenta (0.46). A highest (P<0.05) nitrogen retention was reported for goats on the L. diversifolia supplement (0.45 g dry matter/kgW0.75 /day) than that for goats on C calothyrsus, L. diversifolia and L. pallida which averaged 0.43 g dry matter /kgw0.75 /day.

This study also evaluated the effictcy of in vitro gas production in predicting digestible organic matter intake, organic matter digestibility and microbial nitrogen yield from legume-supplemented diets. Gas production from the fermentation of shrub legume/maize stover mixes was measured in 24 and 96 hour Hohenheimer in vitro gas tests adapted to describe the kinetics of fermentation based on the exponential model P=b (l-e-ct). Gas production components were correlated to feed chemical components, digestible organic matter intake, organic matter digestibility and microbial nitrogen yield. Prediction of digestible organic matter intake and apparent organic matter digestibility from the 96 hour gas production parameters was poor. Prediction of microbial

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MSc and MPhil theses

nitrogen supply using gas production estimates from the shorter incubation was high. However, digestible organic matter intake could not be predicted as accurately as microbial nitrogen supply. It is recommended that the 24 hour gas test can be used in place of the 96 hour test for predicting nutritive value of leguminous shrub forages.

Calliandra calothyrsus, L. pallida and L. diversifolia forage was better than that from L. esculenta for combining with maize stover in diets for growing goats.

Control of nitrogen mineralization from decomposing Gliricidia sepium leaves to optimize nitrogen uptake by maize crop

Nduwayezu Jean Baptiste, MSc (Forestry), 1997

Supervisor: Dr Luther Lulandala

University: Sokoine University of Agriculture, Tanzania

Abstract Decomposition (mass loss) and mineralization studies were conducted at Kitete Village, Kilosa District, Tanzania during the 1995-96 cropping season. The aim was to control the rates of decomposition and nitrogen release from Gliricidia sepium (Jacq.) Walp. leaves through widening their C/N ratios using sawdust.

Litter bags containing a fixed amount of gliricidia leaves (150 g/bag) and variable amounts of sawdust (0, 25, 50, 75, 100% of fixed gliricidia) were used in the decomposition experiment. Different Gliricidia leaf rates (1.5,1.15,0.76 and 0.38 kg dry leaves/plot or 60,45, 30 and 15 kg N/ha respectively) and various gliricidia and sawdust mixtures containing a fixed amount of gliricidia leaves (1.5 kg/plot) and variable amounts of sawdust were used in the mineralization experiment conducted within a maize farm.

The decomposition and mineralization studies revealed that treatments with gliricidia alone had significantly (P=0.002) higher mass loss percentage and nitrogen release but decreased with increasing C/N ratio in gliricidia-sawdust mixtures. Rates of mass loss were influenced by placement depth. Most of the nitrogen from the gliricidia-alone treatments was released within six weeks. In the mineralization experiment nitrate nitrogen was found to dominate the mineral nitrogen, ranging from 67 to 81%. The nitrogen uptake by maize plants, maize height increment and maize crop yields were significantly higher in plots with correspondingly higher C/N ratios with a positive correlation between nitrogen uptake and maize growth (r = 0.762) and maize yield (r = 0.858). A 3-8 weeks period is a critical period of high nutrients demand by the maize crop in the study area. It was, therefore, concluded that the gliricidia (1.5 kg)-sawdust (1.0 and 1.25 kg) mixtures or 2:1 and 2-3:1 C/N ratios should be adopted in the study area for effective control of the rates of decomposition and nitrogen release and hence availability of nitrogen for crop growth and yield.

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MSc and MPhil theses

Factors contributing woodfuei scarcity and the consequent use of crop residues for domestic energy in rural Kenya

Fridah Wilumila Mugo, MSc (Natural Resources), 1997

Supervisors: Dr James Lassoie Dr Jennifer Greene Dr Erick Fernandes

University: Cornell University, USA

Abstract Woodfuei provides 71% of Kenya's energy and 93% of its rural sector's energy requirements. Despite the efforts of tree planting programs in Kenya, reports indicate that the woodfuei deficit increased from 30% in 1980 to 74% in 1995. This study investigated the factors contributing to the scarcity of woodfuei as evidenced by the increased use of crop residues in Naitiri sub-location, a rural community in the Bungoma District of Kenya. Information from a sample of 90 households and three one-day workshops of 25, 10 and 75 participants from the community showed that all households, regardless of socioeconomic status, used crop residues for fuel. Residues provided energy more than 45% of the time for the older households and 39% for the younger households. For the remaining time, most households depended on twigs. The reasons given for the use of residues were shortages of woodfuei and lack of better alternative uses for the residues. The recognized soil contributions of crop residues to improving soil characteristics apparently were not understood in the study area, as residues not used for fuel were burned to make ploughing easier.

Factors contributing to the woodfuei shortage fall into three categories: the level of tree planting, the non-harvesting of trees for fuelwood, and the inefficient utilization of woodfuei. In the first category, the major factors are land tenure and lack of motivation.

Land in this community is inherited by sons from their fathers, but some fathers take as long as 15 years (after the son's marriage) to give their sons land or show them a permanent place where they can farm. Because trees are considered to be a long-term investment, the sons have no incentive to plant them on land that does not belong to them, yet they still require tree products for their various needs. Lack of motivation for all households can be traced to a lack of organized market outlets for tree products because farmers want to invest in an enterprise that will probably bring them income.

The main factors that dissuade households from harvesting trees for fuel are: • lack of knowledge about tree management (trees are left growing indefinitely with no

management or harvest plan) • the tree species planted on the farms are generally for other purposes including income,

construction and timber. Some tree species are rarely harvested for household fuel needs but may be sold for fuelwood to others.

• most trees are planted on farm boundaries, hence they have multiple functions such as fencing, boundary markers and windbreaks. The functional value of these trees is so high that they are rarely harvested for fuel.

• women are responsible for fuelwood collection and cooking while the men plant and control the use of trees. Consequently, the men do.not feel the burden or necessity of providing fuelwood. Meanwhile, in households where the men provide fuelwood, the women tend not to conserve the fuel. Male-headed households where wives are in formal employment and female-headed households were found to have adequate woodfuei resources. This suggests

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MSc and MPhil theses

that the primary variables determining woodfuel availability in a household are: the awareness of the woodfuel burden, access to tree and financial resources, and the decision-making authority between men and women within the household. The groups most affected by the scarcity were land-less widows and sons, and women from polygamous homes.

The major factors contributing to inefficient use of biomass fuels include inefficient stoves (10% efficiency), semi-dry wood (generally dried for only three days), and other wasteful cooking habits. Only 26% of households had energy-efficient stoves and only half of those households used them. In addition, 75% of those interviewed used mostly semi-dry wood for cooking. Fuelwood could be fully dried within 17 days, not the recommended 90 days. With energy conservation technology available to Kenya's households, a saving of over 80% of the current consumption can be attained. Considering this potential, energy efficiency in the study area was far below optimum.

To eliminate woodfuel scarcity and the attendant environmental degradation, community and government should collaboratively develop a concrete plan whereby sons are allocated land once they move to their own households and also agree on a minimum per capita tree population. In addition, rural credit facilities should be provided to enable households to farm optimally. Farmers must be educated on proper tree management practices such as species selection, siting, spacing, and harvesting operations. Men and women must be targeted on woodfuel issues because each contributes to the outcome. Residents need to dry wood properly and use energy-efficient technology to reduce the consumption of biomass energy. Finally, as reports from other countries indicate, there is significant potential for increasing the availability of fuelwood for households by developing markets for poles, timber and woodfuel.

Forest resource management for sustainable development: a case of Mount Meru Forest Reserve in northern Tanzania

Ufoo C Lema, MSc (Environmental and Geographical Science), 1997

Supervisors: Prof Richard Fuggle

University: University of Cape Town, South Africa

Abstract Management systems as applied to most of the world's tropical forests are anthropocentric. In view of this, conservation of these ecosystems has been threatened by overuse and pressure of exotic monocultures. Sustainable forest development aims at utilizing the forest resource without unduly degrading the forest ecosystem.

This study examines the case of Mount Meru Forest Reserve, a tropical montane rainforest in northern Tanzania. The main aim of the study is to investigate human-induced causes of forest degradation and to propose ways to improve the forest management to attain sustainable forest development. The study is based on survey data obtained through semi-structured interviews with 198 informants. Social study methods have been used for data analysis and interpretation.

It has been found that human instinct at the individual, community and national levels emphasizes short-term gain, threatening long-term survival. This has resulted in exploitative use of the forest ecosystem reducing options for its future use. Implementation of forest policies to intensify forest conservation is difficult due to poor supervision, partly caused by the extensiveness of the areas involved, and the large population dependent on forest resources for survival. Raising awareness

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MSc and MPhil theses

of the implications of human actions on these ecosystems is found to be an essential prerequisite for enabling change in attitudes and behaviour and a move towards actions necessary to generate sustainable development. Cooperative ingenuity in the allocation of forest resources is essential. This necessitates considerations for the predicament of the poor majority. Consistent review of government policies is also important. It is recommended that local communities be involved in forest management activities. In addition, immediate action to restore degraded areas is recommended.

Inventory of indigenous agroforestry systems in practice in the West Usambaras

Ernest R Moshi, MSc (Forestry), 1997

Supervisor: Dr Luther Lulandala

University: Sokoine University of Agriculture, Morogoro, Tanzania

Abstract This study was conducted in the Irente, Lwandai and Ubiri villages of the West Usambaras. The main aim was to carry out an inventory of the indigenous component of the agroforestry systems practised by local farmers of these villages.

The specific objectives were: to identify the indigenous agroforestry systems; to examine the structures and functions of the identified indigenous agroforestry systems; to find out the socio-ecological and socio-economic functions of these systems; to identify constraints limiting the productivity of the indigenous agroforestry systems and to indicate ways of improving them.

The data was collected by using unstructured questionnaires and by physical reconnaissance survey made by the researcher. Statistical Package for the Social Sciences (SPSS) was the computer programme used to analyze the data.

Three indigenous farming systems: valley bottom gardens, crops plus trees farms, and home gardens were identified. The last two typify the indigenous agrosilvicultural and agrosilvopastoral systems, respectively. They also indicate a general low productivity of all agroforestry components. The present arrangement and stocking of the woody perennials and herbaceous plants in these indigenous agroforestry systems seems to impart more negative than positive effects on productivity. Other constraints limiting the productivity and sustainability include low soil fertility, lack of extension and veterinary services, unattractive producer prices, scarcity of cultivation land and grazing grounds for livestock, and high prices of chemical inputs such as inorganic fertilizers, biocides and livestock pharmaceuticals. The following were recommended to improve the indigenous agroforestry systems: • improve the arrangement and stocking through planting more trees combined with fodder

grasses in contours and along boundaries • introduce hedgerow cropping systems to arrest the problems of soil erosion and soil fertility • use livestock manure to nourish the exhausted soils.

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MSc and MPhil theses

Effect of Leucaena leucocephala biomass and sawdust on physical and chemical properties of the soil and on growth and yield of soyabean (Glycine max)

Emmanuel Yamoah, MSc (Crop Science), 1997

Supervisor: Dr James Quashie-Sam

University: University of Science and Technology, Kumasi, Ghana

Abstract The effect of sawdust and Leucaena leucocephala biomass on soil physical and chemical properties and on growth and yield of soya bean (Glycine max) were studied in two field experiments. The study was conducted to determine optimum combination level of sawdust and leucaena biomass that can sustain growth and yield of soya bean and to assess treatment effect on the soil and earthworm population.

Sawdust and leucaena were applied at rates 0, 5, 10, and 20 t/ha for experiment I and at 0 and 10 t/ha for experiment II. The stem height, root length, root dry weight, nodule number and nodule diameter of soya bean were determined.

Growth analysis involving leaf area index, leaf area ratio, leaf area duration, net assimilation rate and crop growth rate were carried out. Soil samples were analyzed for N, P, K, C and pH at planting and after harvesting. Soil bulk density, porosity, moisture content and temperature were determined.

Germination was reduced significantly at 20 t/ha application of sawdust. Leucaena application showed significant increase in the leaf area index (P < 0.01), leaf area ratio (P < 0.05), leaf area duration (P < 0.01) and a slight increase in soil nitrogen levels. Leucaena treatments produced soya bean plants which were almost twice as tall (64 cm) as those of the sawdust treatment (37 cm), and also produced almost twice as many pods (26.4 pods) as the sawdust treatments (12.8 pods). Seed yields from leucaena plots were twice (1.88 t/ha) as that of sawdust plots (0.83 t/ha). Sawdust and leucaena combination yield was higher (1.52 t/ha) than that of the control (1.04 t/ha). The main determinant of seed yield was number of pods per plant. At 10 t/ha, sawdust reduced both leaf area index and leaf area ratio significantly (P < 0.05). Earthworm population increased with sawdust application up to 10 t/ha level and declined at 20 t/ha. Soil temperature decreased with increasing levels of sawdust and leucaena application. Sawdust reduced bulk density, and increased porosity and soil water content more than leucaena.

The study revealed that the optimum level of sawdust that can sustain crop production is 10 t/ha.

Propagation of Parinari curatellifoUa Planch ex Benth. and Uapaca kirkiana Muell. Arg. by seeds and stem cuttings

Patrick Paschal Lusinde Mwangingo, MSc (Forestry), 1997

Supervisors: Prof Luther L Lulandala Dr AG Mugasha

University: Sokoine University of Agriculture, Morogdro, Tanzania

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MSc and MPhil theses

Abstract Two experiments on propagation of Parinari curatellifolia and Uapaca kirkiana were carried out at the National Tree Seed Programme (NTSP), Iringa Zonal Tree Seed Centre during December, 1995 - June 1996 with the aim of determining efficient techniques of enhancing the germination of P. curatellifolia seeds and to see whether P. curatellifolia and U. kirkiana could be raised vegetatively through stem cuttings.

P. curatellifolia seeds were subjected to different pre-sowing treatments involving scarification of the seedcoats, soaking in hot water and concentrated sulphuric acid at various storage periods. For vegetative propagation of both P. curatellifolia and U. kirkiana, the possibility of using either basal or terminal parts of the stem cuttings, and the influence of different concentrations of indole-3-butyric acid hormone were tested. The results indicated the existence of serious seed dormancy problems that limit the rate of germination in P. curatellifolia seeds. Only pre-sowing seed treatments by complete and partial removal of the seedcoats gave germination at all the storage periods with the former giving better mean cumulative germination of 34%, germination energy of 30%, germination value of 1.4, complete, total and different dormancy periods of 27.8, 67.6 and 40.6 days respectively. The storage period enhanced early germination in seeds stored for at least 30 days.The combined effect of seed storage for 60 days and pre-sowing treatment by complete removal of the seedcoats gave early germination (within an avarage of 21.3 days).. The results for vegetative propagation indicated a potential for raising both species by stem cuttings with the basal parts combined with hormone application of 375 ppm for P. curatellifolia and 125 ppm for U. kirkiana. The best establishment performances of sprouting, rooting, root number and root length means of 46.7%, 41.3% and 5.5 and 50.8 mm for P. curatellifolia and 62.9%, 53.3% 5.2 and 58.8 mm for U. kirkiana respectively were obtained.

It is concluded that both tree species have the potential to be raised by seeds and stem cuttings. If seeds are preferred in raising P curatellifolia plants, they need to be pre-treated by completely removing the seedcoats to improve the permeability of the seeds to air and water and to overcome the mechanical resistance to embryo growth. The storage of seeds for 60 days before sowing allows the maturation of the embryos and thus enhances their early germination. Since the germination of 34% obtained in the present study is still low and sporadic, other types of dormancy like chemical and physiological or a combination of the two are also suspected to play a role. While the immediate application of the results is being recommended, further research is required to confirm the identity of other types of dormancy still associated with P. curatellifolia seeds in order to raise overall seed germination and improved efficiency and effectiveness of the vegetative propagation technology by stem cutting.

Evaluation of pods from three acacia trees and leaves of Terminalia brownii and Berchemia discolor as dietary supplements for growing goats

Jane J Sawe, MSc (Agroforestry), 1997

Supervisors: Dr James Tuitoek Dr Jared M Ottaro Dr Wilson Kipkore

University: Moi University, Eldoret, Kenya

Abstract This study was carried out at Kimose (Baringd), Kenya, to determine the chemical composition of pods of Acacia tortilis, A. nilotica, A. brevispica and leaves of Terminalia brownii and Berchemia

60

discolor. An in vitro dry matter digestibility and a degradation study using the nylon bag incubation method of the leaves and pods were determined. The influence of supplementing Boer/Galla goats (initial weight 18.6 sd 2.27 kg) with 150 g of the respective supplements of pods and leaves on weight gain and forage intake was also assessed. Green nutritious forage was available during the study period, which was similar to a rainy season.

Goats selected a diet with a crude protein of 22.5% while the supplements had a crude protein ranging from 13.5 to 24.3%. A. brevispica was high in fibre with CF, acid detergent fibre and neutral detergent fibre of manganese, iron and zinc while the browse and supplements were deficient in sodium, sulphur, phosphorus and in some cases copper and zinc.

The control diet and B. discolor were relatively high in tannins (267 and 355 g catechin dry weight equivalent respectively). In vitro dry matter digestibility of the leaves and pods ranges from 40.3% for T. brownii to 68.7% for A. nilotica. Dry matter degradability of browse and supplements in the rumen of fistulated Dorper sheep increased with time. The soluble fraction of the browse and supplements ranged from 8.6% to 20.3%. Dry matter disappearance after 72 hours reached a plateau for A brevispica, T. brownii, and B. discolor. A. nilotica had the highest degradation (79.2%) and T. brownii had the least (43.1%) degradability. In the feeding experiment, supplemented goats grew faster (PO.05) than the non supplemented. Males grew faster and also consumed more supplementary feed (P<0.05) than females. A. tortilis and A nilotica achieved the best liveweight gains and were also the most palatable of all the supplements.

The range of estimated dry matter intake was 715.8 to 861.2 g/day. Estimated dry matter intake per kg W075 was 64.5 to 76.9 and that of estimated forage intake alone was 574.7 to 752.1 g/day. There were no statistical differences (P>0.05) among treatments in these parameters.

Supplementation throughout the year to boost protein and energy intake in this area is necessary; and mineral supplementation should be provided as the browse and the supplements did not supply adequate quantities of some minerals. Rangeland productivity in terms of goat production could be increased if pods of A. tortilis and A nilotica are collected during periods of plenty, stored and used as supplements for goats during the times of forage scarcity.

An evaluation of tree/shrub species and provenances for fodder production, Embu, Kenya

Paul Kipkorir Tuwei, MSc (Forestry), 1997

Supervisor: Prof Luther LLulandala

University: Sokoine University of Agriculture, Morogoro, Tanzania

Abstract This study was undertaken on ongoing agroforestry research at the National Agroforestry Project Embu, Kenya, to evaluate the potential of seven tree or shrub species, some with several provenances, as sources of fodder and their effects on soil chemical properties.

The tree or shrub species and provenances were assessed for survival, biomass and nutritive values. The results for the soil sampling showed average fertility with organic carbon and total nitrogen (total N) depleting, possibly due to decomposition in the case of organic carbon, and to leaching and plant use in the case of total N. With the exception of Mimosa scabrella (with a survival percent of 69.1%), all the tree or shrub species and provenances had plant survival of>

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MSc and MPhil theses

83%. Biomass yields varied significantly between tree or shrub species and provenances, with Acacia angustissima and Sapium ellipticum having the highest and lowest biomass yields respectively.

Nutritionally, all the tree or shrub species and provenances evaluated show potential for becoming important fodder sources in Embu District. All of the tested fodder species have crude protein above the minimum requirements of 8% for ruminants. The exotic species showed a poor in vitro dry matter digestibility compared with local species, but this was compensated by their high leafy biomass production. Overall, Embu (Kenya), Coban (Guatemala), San Ramon (Nicaragua), Madium (Indonesia), Santa Maria de Jesus (Guatemala) and Fortuna (Costa Rica) provenances of Calliandra calothyrsus, San Marcos (Guatemala) and Volcan Salvador (El Salvador) provenances of Acacia angustissima and Rio Hondo (Mexico) with Palenque species than the best local species (Trema orientalis) in the district as shown by their relatively higher total digestible leafy biomass in the second harvest. Further research is recommended on the effects of drying on in vitro dry matter digestibility, acceptability and digestibility of the species by the animals and the long-term effects of these tree or shrub species and provenances on soil chemical properties.

Intake and digestibility of low quality rhodes grass hay and growth of sheep as affected by browse supplement and Magadi treatment

David Cyprian Silayo, MSc (Agroforestry), 1998

Supervisors: Dr G Y Kanyama Phiri Dr J P Mtimuni Dr Moses B Kwapata

University: Bunda College of Agriculture, Univ. of Malawi, Malawi

Abstract During the dry season (September-October) of 1996, an experiment was carried out at Bunda College of Agriculture, 30 km southwest of Lilongwe, Malawi (14 35'S, 33 50'E) and 1118m above sea level, to determine the effect on intake and digestibility of magadi (a sodium desquicarbonate — Na2C03 NaHC03. 2H20) treated forage, and to observe subsequent growth of sheep. Rhodes grass (R), Toona ciliata (T) and Sesbania sesban (S) samples were treated with 0% (control), 5% or 10% magadi suspension. Polyethylene glycol (PEG), a tannin complexing agent, was mixed with a sample of toona and sesbania to compare its effect on gas production with samples treated or not treated with magadi. Thus the treatments were RO, R5, RIO, SO, S5, S10, TO, T5, T10, SPEG, TPEG (indicating that R, S and T treated with 0, 5, or 10% magadi of polyethylene glycol respectively) and maize bran, here called madeya (MD). These 12 treatments (each 500 mg) were incubated in cattle rumen liquor in 100 ml syringes at 39 C for 96 hours.

The results indicated that the 10% magadi treatment lowered gas production compared with the control or polyethylene glycol. Treatments T5, TPEG, S5 and SPEG increased gas production compared with the control. However, the T5 treatment produced more gas (93.5 ml) than the TPEG (76.7 ml), indicating that in toona, the former was more effective than the latter, while the S5 treatment produced slightly less gas (104.9 ml) than the SPEG (108.6 ml), indicating that in sesbania, magadi treatment at 5% level was not as effective as polyethylene glycol in stimulating gas production. It was concluded that, like polyethylene glycol, magadi suppresses tannins (and possibly other anti-nutritional factors), thereby facilitating degradation of the feed, but higher levels of magadi lower the microbial degradation.

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MSc and MPhil theses

In the intake and digestibility studies, the TO, T5, T10, SO, S5 and S10 treatments were ground and each mixed with MD in 1:1 ratio. The RO, R5, and RIO hays were basal feeds, and were fed to correspond with the magadi levels of the respective treatments (e.g., R5 fed with S5 or T5). The treatments were allotted to 18 sheep (mean live weight 35 ± 4 kg) in a completely randomized design with three animals per treatment.

The result indicated that dry matter and organic matter intake and digestibility as well as urine production increased significantly (p<0.05) with increased magadi level, though the T5 treatment lowered the dry matter intake, dry matter digestibility and organic matter digestibility. However, the magadi treatment depressed the crude protein digestibility. Sesbania supplementation significantly increased crude protein intake, crude protein digestibility, dry matter intake, dry matter digestibility, organic matter intake and organic matter digestibility over toona. The results indicated that toona and sesbania respond differently to treatments with different magadi concentration.

The growth study lasted 60 days. Twenty four-intact male sheep (initial average weight 40.8± 7.2 kg) were allotted to the six rations. However, the Rhodes grass hay (the basal feed) was not treated with magadi. A concentrate composed of 70% MD and 30% of each treatment (SO, S5, S10, TO, T5, and T10) was fed to the sheep to supply 45-50 g crude protein (depending on live weight) to enable the sheep to grow at a rate of 150 kg per day. At the end of the 60 days, the expected growth rate (150g/day) was not achieved and there were no significant differences (p<0.05) between treatment within the two browses and among the three different levels of magadi treatment. However, sesbania supplementation and magadi treatment tended to increase the daily gain. It was concluded that treating forages with magadi produces variable results depending on the type of forage and the level of magadi used and that sesbania can only substitute as a protein supplement in ruminant diet under desparate circumstances.. More studies are required to determine the magadi/browse combination levels that will give the best results in forage intake and digestibility, hence growth ruminants.

Tree planting under customary land and tree tenure systems in Malawi: an investigation into the importance of marriage and inheritance patterns

Jamie Douglas Hansen, MSc (Agricultural Economics), 1998

Supervisors: Dr Susan Minae (ICRAF) Dr David Ngugi (ICRAF) Dr Frank Place (ICRAF) Dr Martin K Luckert

University: University of Alberta

Abstract Fortmann and Bruce (1988) note that 'forestry and agroforestry policies along with programs and projects require a sound tenure strategy' and 'a sound tenure strategy will avoid some of the most common pitfalls of forestry and agroforestry planning'. It is important that the effects of traditional customary tenure on management policies can take these effects into policy consideration. This thesis endeavours to improve understanding of customary tree tenure and the effects that customary inheritance and the changing traditional marriage systems have on the management of trees in individual households of the Chewa in central Malawi.

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MSc and MPhil theses

Analysis of some socio-economic factors that affect the adoption of agroforestry technologies in the Yensi Valley in Akwapim, Ghana

Paul Sarfo-Mensah, MPhil, 1994

Supervisors: Dr SJ Quashie-Sam

Dr Kwasi Nsiah-Gyabaah

University: University of Science and Technology, Kumasi, Ghana

Abstract Interest in agroforestry as a concept, land-use method, and rural development tool is derived from its potential to solve a variety of land-use problems that afflict developing countries. The adoption of agroforestry by farmers has therefore become an important research domain. This thesis analyses some socioeconomic factors that affect the adoption of agroforestry methods in the Yensi Valley. The research rests on the premise that the attitude, perceptions and socioeconomic environment of farmers affect their decision to adopt agroforestry. In this study 28 practitioners and 28 non-practitioners of agroforestry were sampled from seven communities for in-depth study and analysis. A combination of structured interview and rapid rural appraisal techniques were used in data collection. Data was analyzed both qualitatively and quantitatively.

The study revealed that farmers' preferences of agroforestry techniques were dictated by felt needs and objectives as well as the constraints and opportunities of their households. A control factor, however, was the preference of the landlord where the adopter was a tenant. On the aggregate, alley farming was found to be the most preferred method in terms of the seven criteria (or objectives) indicated by farmers for technology selection: food, cash, fuelwood, soil fertility, fodder, land tenure problems, and labour requirement. In terms of cash, fuelwood supply and labour conservation, farmer preference was for woodlot. However, most tenant farmers said landlords were not particularly interested in woodlots because of their perception that woodlot would reduce their immediate share of food and cash.

It was established that farmers have a deep knowledge of indigenous trees and their uses. Their knowledge cuts across a wide spectrum of socioeconomic attributes of trees (medicinal, spiritual, fallow management, tree crop associations, i.e. positive and allelopathic effects, propagation methods, etc.). Most of these trees have not yet been deliberately planted for intensive agroforestry purposes. This provides good opportunities for adoption and adaptation into the agroforestry systems.

It was also found that the perception of socioeconomic factors that affect adoption varies among practitioners and non practitioners. Practitioners considered access to credit as the most critical constraint to adoption while non practitioners perceived land and tree tenure systems as the most inhibiting factors to adoption. A Prohibit analysis also showed tenure status and income levels of farmers as the important significant determinants of adoption.

The conclusion of the study is that a flexible tenure system and farmer accessibility to credit would increase adoption of agroforestry technologies among farmers.

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Theses submitted for Dipldme Ingenieur agronome and

Dipldme Ingenieur des eaux et forets

Possibility d'utilisation d'arbustes comme source d'engrais vert dans la production du sorgho a Samanko

Siaka Dembele, Diplo'me (Inge'nieur agronome), 1996

Supervisor: Dr Mamadou Djimde' (ICRAF)

Institute: Institut Polytechnique Rural de Katibougou, Mali

Resume' La pauvrete des sols en nutriments constitue sans nul doute l'un des facteurs limitants les plus importants pour atteindre une autosuffisance alimentaire au Sahel. Plusieurs tentatives de solutions envisage'es ont vu leurs limites dans le temps. La recherche d'un systeme cultural ecologiquement stable, economiquement viable et culturellement acceptable par les producteurs et cela a partir des ressources locales s'impose.

Afin de determiner l'effet d'engrais verts d'arbustes ligneux sur la production du sorgho, des etudes ont ete menees de mars a dwcembre 1996 a Samanko. Le travail a commence par une enquete d'identification d'especes d'arbustes abondantes et peu utilisees dans la zone. Ensuite un essai a e'te' conduit en station pour determiner l'effet de la biomasse enfouie de deux especes retenues, notamment Guiera senegalensis et Combretum lecardii, sur la production du sorgho. Les resultats obtenus indiquent que l'apport d'engrais vert de G. senegalensis et de C. lecardii semble induire une augmentation de rendements du sorgho.

Disponibillte' fourragere et commercialisation de fourrages ligneux sur les marches de Bamako

Tiekoura Coumare, Dipldme (Inge'nieur agronome), 1996

Supervisor: Dr Elias Ayuk (ICRAF)

Institute: Institut Polytechnique Rural de Katibougou, Mali

Resume' Ce memoire traite de la disponibilite fourragere et de la commercialisation des fourrages ligneux sur les marches de Bamako. L'objectif principal de cette etude est la connaissance des essences ligneuses fourrageres disponibles sur les marches de Bamako et d'etudier l'influence de leur commercialisation sur le revenu des menages.

Les objectifs specifiques sont les suivants :

Individual training at ICRAF

• identifier les ligneux fourragers rencontres sur les marches ; • determiner le circuit de commercialisation et le prix de vente des fourrages sur les marches ; • degager le revenu brut generer par la vente de fourrage ; • determiner les quantites de fourrage vendues sur les marches ; • identifier la couche sociale interessee par la vente de fourrage ; • degager l'influence de la vente de fourrage sur la consommation des menages. Cette etude a ete entreprise sur trois marches a Djikoroni-Para, Daoudabougou et Hippodrome. En fonction de nos criteres de choix nous avons retenu pour l'enquete six vendeurs au marche de Djikoroni-Para, neuf au marche de Daoudabougou, et dix au marche de l'Hippodrome.

lis etaient suivis de pres et on cochait successivement les prix des fourrages vendues aux differents acheteurs. En fin de vente, par une operation d'addition on determinait le revenu brut journalier genere par la vente de fourrage par individu et par espece.

Nous avons rencontre quatres especes ligneuses fourrageres sur les marches prospectes. Ce sont: Pterocarpus erinaceus, Pterocarpus lucens, Pterocarpus santalinoides et Afzelia africana.

Ces especes vendues sur les marches etaient toutes cueillies dans la nature. La bicyclette est principal moyen de transport utilise. Les fourrages achetes sont destinees principalement aux petits ruminants. Le revenu tire de la vente de fourrage est utilise pour couvrir l'ensemble des besoins des manages. Sur les marches le prix moyen de vente le plus eleve quelque soit 1'espece a ete de 200 Fcfa/kg de fourrage.

Possibility d'utilisation d'arbustes comme source d'engrais vert dans ia zone de Samanko : capacity fertilisante et perspectives agroforestieres

N'Dji Coumare, Dipldme (Inglnieur), 1996

Supervisor: Dr Mamadou Djimde (ICRAF)

University: Institut Polytechnique Rural de Katibougou, Mali

Re'sume' La degradation des sols et leur baisse de productivity est un phenomene marquant en zone semi-aride de l'Afrique de l'ouest. L'utilisation des engrais mineraux n'est pas a la portee des paysans en raison de leurs couts e'leve's. La fertilisation biologique notamment l'emploi de 1'engrais vert constitue une alternative pour atte'nuer les problemes de baisse de fertility des sols. La presente etude se situe dans ce cadre.

Guiera senegalensis et Combretum lecardii ont ete identifies comme sources potentielles d'engrais vert par le biais d'une enquete en raison de leur abondance et de leur utilisation tres limitee par les paysans dans la zone de Samanko. La biomasse foliaire de G. senegalensis semble se mineraliser plus vite que celle de C. lecardii.

L'apport de 2 t/ha des engrais verts des deux especes identifiees sur la base de la fertilisation mine'rale de 13 kgs d'azote pratiquee par les paysans dans la zone et de 4 t/ha n'ont pas eu un effet immediat tres perceptible sur les proprietes du sol et le rendement du sorgho.

Une induction d'augmentation de rendement et cela sur un sol laisse en jachere depuis plusieurs ann6s indique les potentialites des deux especes comme source d'engrais. Vu la degradation de la

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vegetation naturelle et la disparition des jacheres, des possibility de leur integration dans le systeme de production ont ete proposees.

Commercialisation des produits forestiers non-ligneux sur les marches de Fana

Abdoulaye Alcaya Toure, Diplome (Ingenieur agronome), 1996

Supervisor: Dr Elias Ayuk (ICRAF)

Institute: Institut Polytechnique Rural de Katibougou, Mali

Resume* Au Mali les produits forestiers n'ont pas ete suffisamment encourage, bien que le decret n° 9/PGRM du 27/01/1975 reglemente la commercialisation des amandes de karite et du beurre de karite. Peu d'information existe sur ces produits et la presente etude se donne pour objet de degager 1'importance economique de ces produits.

Le secteur dit informel peut ameliorer de facon significative le revenu des populations rurales s'il est bien structure.

Les femmes rurales, tres generalement analphabetes, s'occupent du ramassage de ces produits forestiers non ligneux et de leur transformation, soit pour la consommation soit pour la vente afin d'ameliorer le revenu familial. C'est pourquoi le secteur est demeure comme un point de production pour la femme rurale.

Le present resume donne les resultats des six mois d'enquete realisee sur les marches de Fana et Tingole. La plupart des vendeurs et vendeuses sont maries et sont analphabetes, l'age moyen est compris entre 33 et 58 ans. Les marches villageois situes a 120 km au nord-est de Bamako sont concernes par l'etude. Durant les six mois de l'enquete 24 produits bruts ou transformes ont ete repertories. Mais huit seulement de ces produits apparaissent comme source potentielle de revenu en raison de leur apport monetaire par mois superieur ou egal a 2.000 francs de 1'existence d'un marche' national deja important, et de leur utilisation. II s'agit des amandes du beurre, du savon traditionnel de Vitellaria paradoxa, des graines brutes et fermentees de Parkia biglobosa, des fruits de Landolphia senegalensis, des fruits de Tamarindus indica, et la gomme du Combretum glutinosum.

Enfin le revenu tire est prioritairement investi dans l'achat de condiments et de cereales.

Evaluation de provenances de Gliricidia sepium : perspectives agroforestieres de I'espece pour la production fourragere dans la zone semi-aride au Mali

Mahaman Abatchia Boukar Madai, Diplome (Ingenieur eaux et forets), 1997

Supervisor: Dr Mamadou Djimde (ICRAF)

University: Institut de formation et de la recherche appliquee de Katibougou, Mali

Re'sume' Les perfomances de trois provenances de Gliricidia sepium (ILG50, ILG74 et Retalhuleu) ont ete e'value'es pendant trois periodes en saison seches (octobre, avril et juin). Cet essai a ete implante

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sur deux sites differents de par leurs pluviometries. II s'agit de la station de Samanko a 25 km au sud-ouest de Bamako et celle de Cinzana a 45 km au nord de Segou. Les pluviom&ries annuelles moyermes varient respectivement au tour de 824.9 mm et 663.4 mm.

Apres 1'analyse des resultats, la provenance ILGSO s'avere Stre la meilleure fourrage're aussi bien a Samanko qu'a Cinzana avec respectivement 3,39 tms/ha/an et 2,36 tms/ha/an suivi de ILG74. Retalhuleu semble etre plus sensible a Faridite'.

L'analyse chimique a montre' que G. sepium contient une bonne teneur en proline brute, comparable a celle des meilleures le'gumineuses herbacees. La production fourragere de G. sepium peut se faire dans les systemes de production paysan sous forme de banques fourrageres, plantation en bordures de parcelles de culture de contre saison, plantation en courbes de niveau et plantation intercalaire dans les champs de cultures pluviales.

Les banques fourrageres comme preconise' dans la pr6sente e'tude expeiimentale semblent etre plus prometteuses.

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Individual training of scientists at ICRAF

Preamble

ICRAF places strong emphasis on building the capacity of partner research institutions and universities to develop and conduct agroforestry research. 'Through individual training project, ICRAF aims to strengthen agroforestry research and educational systems, particularly for partner institutiohs. Sustained effort in this programme will enable our partners to develop sufficient scientific expertise to respond to agroforestry research needs. To achieve this, ICRAF and its partners have developed collaborative programmes that provide opportunities for young scientists to excel in research and education in agroforestry. Under this arrangement, competitive fellowships are made available for young scientists and students to carry out agroforestry research with ICRAF scientists at our collaborative research sites.

The aim of individual training is therefore to build the capacity of individual scientists and institutions in agroforestry research. The specific objectives are: • to impart ICRAF's experiences in agroforestry research and training to needy individuals and

institutions with potential to multiply and share it • to pool and coordinate agroforestry research capacity at present scattered in various

institutions and disciplines, to focus on common research issues and speed up the process of finding solutions

• to create opportunities for exchange of Information and evolution of collaborative programmes among institutions involved in agroforestry research, education and extension.

Categories of trainees

We categorize trainees in the following ways: Postgraduate fellows: for students registered for Masters or PhD degrees or equivalents, and for whom the work will result in a thesis of dissertation Research fellows: for non-degree researchers. May include academic staff on sabbatical leave. Student attachments: for undergraduate/college students only, who need to be attached briefly to a research or development institution as part of their field experience.

Whereas trainees in the first two categories can carry out their research at any fitting research site and country, all student attachments must be implemented in die country where the student is resident.

Eligibility

The project working mode is strictly collaborative, and arrangements are generally made with research and educational institutions, although some exceptions can be considered on merit. Individuals are advised to apply for fellowships through their employers. Applications from developing countries are given priority. Adequate financial arrangements must be completed before the awardee is allowed to travel to the research site/s.

Individual training of scientists at ICRAF

Application procedures

Applicants should submit application forms (Annex 1 provides a sample application form) to ICRAF. In addition, applicants are required to submit: • a detailed research proposal, under the headings: title, objective, hypothesis, literature review,

methods of data collection and analysis, budget and literature cited • an up-to-date curriculum vitae • evidence of financial support (those requesting ICRAF to help find support must clearly state

so) • two passport size photographs of the applicant.

To guide the choice of relevant research topics, ICRAF produces a booklet each year with research topics for potential individual trainees.

Applicants for postgraduate and research fellowships should direct their forms and other documents to:

Leader, Capacity and Institutional Strengthening Programme International Centre for Research in Agroforestry PO Box 30677 Nairobi, Kenya Tel: +254 2 521450; fax: 254 2 521001; telex: 22048 ICRAF E-mail: icraf@cgiar.org

Applications for student attachment to a research site should be directed to and processed by the national institution responsible for the site. ICRAF will be consulted only where its scientists will be involved in the supervision. Trainees in Kenya wishing to be attached at ICRAF headquarters in Kenya are required to forward their applications to the above addressee.

Criteria for consideration

Consideration of the application will be based on the following criteria: • relevance of applicant's qualification and experience to the research to be undertaken • relevance of the research proposal to research at the desired site • availability of scientific capacity to supervise the applicant • availability of facilities and resources to implement the training • applicant's potential to carry on with similar work after completing the training.

Letter of agreement

Each successful applicant will be issued with a letter of agreement from the Director Development at ICRAF. The contents of the letter are binding once it has been signed by the collaborating institutions and the trainee. Note that a letter of agreement will be issued only after the host country (where applicable) has granted permission for the trainee to undertake research at the specified site/s.

General terms and procedures for individual training

Answerability

All trainees participating in this programme are provided with at least two supervisors (one from the home university and the other from ICRAF). The only exception to this is for senior fellows on

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sabbatical leave. Trainees are expected to secure approval of their research activities from their supervisors before they collect or analyze any data.

Working hours

Trainees are expected to follow normal working hours applicable to ICRAF staff at the research site/s where their programme is being implemented. However, trainees are expected to make themselves available for work outside official working hours when circumstances so demand.

Leave

Individual trainees whose programmes are longer than six months will be entitled to two days of annual leave per month. The leave cannot be accumulated from year to year, nor can cash payments be accepted in lieu of leave. Leave can only be accepted after three months of training. No additional travel or other perquisites are granted to trainees, save as spelled out in the letter of agreement.

Sick leave may be taken on the advice of a qualified doctor. ICRAF reserves the right to discontinue a trainee's programme in the case of prolonged or repeated sickness affecting their performance.

Maternity leave may be granted to trainees on programmes of at least one year duration. Leave conditions will be the same as for annual leave.

Special leave may be granted to any trainee in circumstances warranting special consideration. The supervisor and coordinator will decide on such cases. Stipend payment will be suspended if the trainee takes any leave that is longer man 24 days.

Travel

Trainees who are funded by ICRAF directly or indirectly (e.g. through an agreement with ICRAF's partners) will be provided with economy class return ticket by the most direct route from the airport nearest to the home institution to the airport nearest to the designated research site.

While on training, trainees may travel provided they get authorization from the supervisor. In such cases, the travel has to be directly related to their studies, and they will be expected to write trip reports to the supervisor and Capacity and Institutional Strengthening Programme leader.

Stipends

Stipends will be paid to trainees as stipulated in the letter of agreement, on a monthly basis. Advance payment of up to three months may be paid if the supervisor and coordinator consider the training circumstances warrant such advances.

Transport

Individual trainees will have transport arrangements included in their letters of agreement. Driving ICRAF vehicles is not authorized unless it is negotiated in advance and included in the letter of agreement or amendments thereto. Authorized persons must have a valid driving licence and meet all insurance requirements. Private use of ICRAF vehicles is prohibited.

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Supervision, monitoring and reporting

Postgraduate fellows will normally have two supervisors, an academic supervisor appointed by the university concerned and an ICRAF scientist to supervise field work. The academic supervisor is responsible for assisting the fellow to meet the degree requirements. The field supervisor must be involved at all stages in the processing of an application, and is responsible for implementation of the agreed programme of work. On arrival, the successful trainee will be expected to consult supervisors and develop a programme of work covering the entire period of training. The supervisors approve the programme and submit a copy to the coordinator. The two supervisors are expected to consult each other regularly to ensure continuity and quality of work. All trainees are required to submit progress report/s to their supervisors. The supervisors will fill in their sections and submit to the Capacity and Institutional Strengthening Programme leader. ICRAF reserves the right to terminate the services of trainees whose progress is considered unsatisfactory. Failure to submit a report without a convincing explanation may be considered as unsatisfactory progress. At appropriate stages in the course of training, the supervisors may recommend that the trainee give a seminar or participate in a technical meeting. In the case of the latter, the associated costs should be available in the trainee's budget, or identified by the supervisors.

All trainees are required to submit a final report before leaving ICRAF The content of the report will be determined by the student and the supervisors, but must include an item on the experience of the student at ICRAF.

Publishing

Publications arising from research carried out at ICRAF's collaborative research sites must be cleared by the publications committee at ICRAF An acknowledgement of the contributions made by ICRAF, national host institutions and sponsors is required. In the case of postgraduate students, a copy of the approved thesis or dissertation has to be deposited with the ICRAF library after completion of studies.

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Annex 1. Sample Application Form INTERNATIONAL CENTRE FOR RESEARCH IN AGROFORESTRY CENTRE INTERNATIONAL POUR LA RECHERCHE EN AGROFORESTERIE

al CENTROINTERNACIONAL DEINVESTIGACION EN AGROFORESTERIA

ICRAF House, United Nations Avenue, Gigiri PO Box 30677, Nairobi, Kenya Telephone: +254 2 521450, via USA +1650 833 6645; fax: +254 2 521 001, via USA +1 650 833 6646; taiex: 22048; cable: ICRAF; e-mail: iCRAF@coJar.ora

Applications are considered four times a year, i.e. last week of January, April, July and October. Consider this before •ending in your application

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