Research Article Dry Matter Production, Nutrient Cycled...

Research ArticleDry Matter Production Nutrient Cycled and Removed and SoilFertility Changes in Yam-Based Cropping Systems withHerbaceous Legumes in the Guinea-Sudan Zone of Benin

Raphiou Maliki1 Brice Sinsin2 Anne Floquet3 Denis Cornet4

Eric Malezieux5 and Philippe Vernier4

1 Institut National des Recherches Agricoles du Benin (INRAB) PO Box 2128 Calavi Benin2Faculte des Sciences Agronomiques de lrsquoUniversite drsquoAbomey-Calavi (FSAUAC) PO Box 01-526 Cotonou Benin3Centre Beninois pour lrsquoEnvironnement et le Developpement Economique et Social (CEBEDES) PO Box 02-331 Cotonou Benin4Centre de Cooperation Internationale en Recherche Agronomique pour le Developpement (CIRAD)34398 Montpellier Cedex 5 France5Centre de Cooperation Internationale en Recherche Agronomique pour le Developpement (CIRAD) UPR Hortsys34398 Montpellier Cedex 5 France

Correspondence should be addressed to Raphiou Maliki malikirdyahoofr

Received 13 December 2015 Accepted 22 May 2016

Academic Editor Zeng-Yei Hseu

Copyright copy 2016 Raphiou Maliki et alThis is an open access article distributed under the Creative CommonsAttribution Licensewhich permits unrestricted use distribution and reproduction in any medium provided the original work is properly cited

Traditional yam-based cropping systems (shifting cultivation slash-and-burn and short fallow) often result in deforestation andsoil nutrient depletion The objective of this study was to determine the impact of yam-based systems with herbaceous legumeson dry matter (DM) production (tubers shoots) nutrients removed and recycled and the soil fertility changes We comparedsmallholdersrsquo traditional systems (1-year fallow ofAndropogon gayanus-yam rotation maize-yam rotation) with yam-based systemsintegrated herbaceous legumes (Aeschynomene histrixmaize intercropping-yam rotation Mucuna pruriensmaize intercropping-yam rotation) The experiment was conducted during the 2002 and 2004 cropping seasons with 32 farmers eight in each site Foreach of them a randomized complete block design with four treatments and four replicates was carried out using a partial nestedmodel with five factors Year Replicate Farmer Site and Treatment Analysis of variance (ANOVA) using the general linear model(GLM) procedure was applied to the dry matter (DM) production (tubers shoots) nutrient contribution to the systems and soilproperties at depths 0ndash10 and 10ndash20 cm DM removed and recycled total N P and K recycled or removed and soil chemicalproperties (SOM N P K and pH water) were significantly improved on yam-based systems with legumes in comparison withtraditional systems

1 Introduction

One of the most serious problems of farming system is theexcessive reductions of agricultural productivity resultingfrom major degradation of soil fertility In 1990 EdouardSaouma wrote that the most serious problem of Africancountries in the future can be that of land degradation [1] Tounderstand how and why lands become degraded one needssome knowledge of the physical environment populationcultivation history and farming systems [2 3]

Current yam-based cropping systems which involveshifting cultivation slash-and-burn or short fallow oftenresult in deforestation and soil nutrient depletion [4] Aslong as population pressure was low the cropping phase wasshort compared to the fallow period Three or four years ofcultivation followed by ten years or more of fallow for exam-ple allows the accumulation of easily degradable organicmatter to regenerate soil fertility [5 6] Where populationincreases available land per inhabitant is reduced and fallowperiods shorten Traditional long-fallow shifting cultivation

Hindawi Publishing CorporationScientificaVolume 2016 Article ID 5212563 12 pageshttpdxdoiorg10115520165212563

2 Scientifica

can no longer continue inmost of humid Sub-SaharanAfricaIncreasing population densities are posing a serious threatto natural resources and agricultural production Farmersrsquoresponse to higher food demand has been either an increasein cultivated area or a reduction of fallow period Theminimum fallow duration to maintain crop production wasestimated at 12 years [7] Fallow periods in most of the humidzone of West and Central Africa are actually between 2 and5 years [8] reinforcing the need to seek alternative foodproduction systems [7]

Yam (Dioscorea spp) is a tuber crop widely cultivatedin the humid and subhumid lowland regions of West Africaand the Caribbean [9] More than 90 of the worldwideproduction (40 Mt fresh tubersyear) is produced in WestAfrica [10] Yam is grown in traditional cropping systemsas the first crop after land clearance yielding about 10 t offresh tuberhayear [11] but when the soil fertility is high itcan easily reach 25ndash30 tha in farm fields [12] with Dioscoreacayenensis-rotundata varieties In Benin nowadays farmershardly have the possibility to rely on long duration fallow andyam is being cultivated in 1- or 2-year herbaceous fallow ormaize rotation systems with manual incorporation of residueinto the soil [13 14] Smallholder farmers removed importantquantities of nutrient from their soil without applying a suffi-cient quantity ofmanure or fertilizer to replenish the soil [15]

Yam cultivation in West Africa is now confronted withthe scarcity of fertile soil available for clearing [4] In Beninnowadays farmers hardly have the possibility to rely onlong duration fallow and yam is being cultivated in 1- or 2-year herbaceous fallow-yam or maize-yam rotation systemswith manual incorporation of residue into the soil [1314] Smallholder farmers removed important quantities ofnutrient from their soil without applying a sufficient quantityof manure or fertilizer to replenish the soil [15]

The decline in yam yields under continuous cultivationhas led to the largely accepted conclusion that yam requiresa high level of natural soil fertility (organic matter andnutrient) [16] Since the demand for yam keeps increasingdue to the continued population growth reserves of arableland are diminishing and fallow duration is decreasing It isbecoming necessary to sustainably increase yam productivityin sedentary cropping systems [16] There is a dire needtherefore to assess in farmersrsquo conditions the economicperformance of sustainable cultivation techniques Ongoingsoil degradation could be reduced by the adoption of newfarming techniques such as improved fallows of herbaceouslegumes [17 18]

Studies on improved fallow practices are generally grain-oriented (cereals such as maize) whereas very little hasbeen done on root and tuber crops especially yam Com-parative studies are lacking that assess the effects of yam-based technologies with herbaceous legumes intercrops andshort fallows on yam production and soil properties inthe savannah transition agroecological zone of Benin Wecompared in a perennial experiment for 4 years with 2-yearrotations smallholder farmersrsquo traditional rotations maize-yam or 1-yearAndropogon gayanus fallow-yamwith rotationsintercropped Aeschynomene histrix with maize-yam or inter-cropped Mucuna pruriens with maize-yam The objective of

Figure 1 Study area location in the savannah transitional agroeco-logical zone of Benin

this study was to determine the impact of yam-based systemswith herbaceous legumes on dry matter (DM) production(tubers and shoots) nutrients removed and recycled and thesoil fertility changes

2 Materials and Methods

21 Study Sites The study was carried out in the Guinea-Sudan transition zone of Benin (centre of Benin) in four sitesMiniffi (District of Dassa-Zoume) Gome (Glazoue) Akperoand Gbanlin (Ouesse) with latitudes 7∘451015840 and 8∘401015840 northand longitudes 2∘201015840 and 2∘351015840 east (Figure 1)

The climate is tropical transitional Guinea-Sudan with arainfall distribution gradient from bimodal (Southern Benin)tomonomodal (Northern Benin)The average annual rainfallduring the study period was 1052mm (2002) 1386mm(2003) 983mm (2004) and 797mm (2005) The rainfallregime in the study area is variable and unequal distribution(ie number of rainy days per month) varies from one siteto another The 2002 and 2003 cropping seasons were wetand had better rainfall distribution with an average annualprecipitation of 1200mm whereas 2004 and 2005 were dry(890mm) with relatively low rainfall distribution

Most of the soils are tropical ferruginous soils [19] origi-nally fromPrecambrian crystalline rocks (granite and gneiss)and classified as plinthosols (Gbanlin and Akpero) and luvi-sols (Miniffi and Gome) [20] (Table 1) Miniffi Akpero andGbanlin are located on a plateau while Gome is on lowlandAkpero is close to forest whileGbanlinMiniffi andGome arefar There is a rising gradient of fertility from the continuouscropping system on degraded soils towards the forests Thisdegradation is related to soil organic matter decrease whichleads to nutrient depletion (nutrients removed in the cropharvest leaching and erosion) Vegetation is a degradedwoody savannah type Maize yam cassava and groundnutare annual cropping systems and the cash crops are cottonand soybean Mineral fertilizer application appears to beessential Smallholder farmers use fertilizers on maize ondepleted soils depending on cash and inputs availabilityCotton is not mixed cropping but pure crop in rotation withother crops (maize or sorghum)

Scientifica 3

Table1Cr

opping

calend

arof

yam-based

crop

ping

syste

msw

ithherbaceous

legumes

andshortfallowin

the2

002-2003

and2004-2005crop

ping

season

s

Dec

Jan

Feb

March

April

May

June

July

Aug

Sept

Oct

Nov

Dec

2002

or2004

cropping

seasons

T0Naturalfallo

wof

Andropogon

gayanu

sSlashing

andbiom

assincorpo

ratio

n(ridging

)

TMLand

slashingand

plou

ghing

Maize

plantin

gNPK

application

andweeding

Weeding

and

urea

application

Maize

harvestin

gSlashing

andbiom

assincorpo

ratio

n(ridging

)infurrow

TMA

Land

slashingand

plou

ghing

Maize

plantin

gNPK

application

Ahistr

ixplantin

gandweeding

Weeding

and

urea

application

Maize

harvestin

gSlashing

andbiom

assincorpo

ratio

n(ridging

)infurrow

TMM

Land

slashingand

plou

ghing

Maize

plantin

gNPK

application

andweeding

Mucun

aplantin

g

Weeding

and

urea

application

Maize

harvestin

gSlashing

andbiom

assincorpo

ratio

n(ridging

)infurrow

2003

or2005

cropping

season

T0Seed

yam

plantin

gmou

ndsc

apping

with

mulch

material

yam

staking

and

weeding

Weeding

Weeding

Yam

harvestin

g

TMSeed

yam

plantin

gmou

ndsc

apping

with

mulch

material

yam

staking

and

weeding

Weeding

Weeding

Yam

harvestin

g

TMA

Seed

yam

plantin

gmou

ndsc

apping

with

mulch

material

yam

staking

and

weeding

Weeding

Weeding

Yam

harvestin

g

TMM

Seed

yam

plantin

gmou

ndsc

apping

with

mulch

material

yam

staking

and

weeding

Weeding

Weeding

Yam

harvestin

g

T0one-yearfallow-yam

rotatio

nTM

maize-yam

rotatio

nTM

AA

eschynom

eneh

istrix

maize

intercropp

ing-yam

rotatio

nTM

MM

ucun

aprurien

smaize

intercropp

ing-yam

rotatio

n

4 Scientifica

22 On-Farm Experiment The concept of the experimentwas to produce residue biomass followed by planting yam inrotation cropping systems A previous cover crop (fallows orintercroppedmaizelegume) was designed to provide organicmatter for the following main crop (yam) (Table 1)

Smallholders carried out two-year rotations experimentof yam-based cropping systems repeated twice (2002ndash2005)on-farm with single-harvest late maturing variety of yamldquoKokorordquo (Dioscorea rotundata) This is one of the mostcultivated species in the study area due to its good aptitude forconservation and processing into dried tubers (the so-calledchips) flour and starchy paste (locally called amala) [21] Weconducted the experiment with 32 farmers eight in each site(Miniffi Gome Akpero and Gbanlin) For each of them weused a randomized block design with four replications andfour levels of treatment Plot size was 10m times 10m (total of1 600m2 per farm) The four treatments were as follows

(i) T0 (Control 1) T0 is one-year fallow-yam rotationwhich is a common practice in the area A naturalfallow of Andropogon gayanus grass was grown in thefirst year

(ii) TM (Control 2) TM indicates maize-yam rotationwhich is also a common practice in the area Maizewas planted (spacing 80 cm times 40 cm) in April of thefirst yearWith recurring drought stress exacerbated by highlyvariable and unpredictable rains in the study areasome farmers grow a second crop which oftenfails This corroborates the great interest of themaizeleguminous crop when no second crop isplanned

(iii) TMA TMA is intercropped Aeschynomene histrixwith maize-yam rotation maize was planted in Aprilof the first yearA histrix seeds (7 kg haminus1) weremixedwith dry sand (34 sand and 14 seeds) and sown twoweeks after the maize

(iv) TMM TMM is intercropped Mucuna pruriens withmaize-yam rotation maize was planted in April of thefirst year M pruriens seeds (25 kg haminus1) were sownat spacing 80 cm times 40 cm in May six weeks after themaize

On treatments TM TMA and TMM 100 kg haminus1 NPKfertilizer (14 N 10 P and 117 K) was applied to maizein April and 50 kg haminus1 urea (46 N) in June The maizewas harvested in July The grainless M pruriens and Ahistrix crops were mowed 140 and 180 days respectively afterplanting Organicmatter was incorporated inmoulds and lefton the surface asmulch inOctober and then yamwas planteddirectly on these moulds without mineral fertilization

23 Data Collection Composite soil samples were collectedin each field before the beginning of the experiment alongplot transects at soil depths of 0ndash10 cm and 10ndash20 cm (32 farmfields times 2 depths = 64 samples) in order to determine soilcharacteristics At the end of 2005 before yam harvestingcomposite soil samples were collected at the same depths in

Table 2 Quantity of biomass (t haminus1) dry matter and nutrientscontents ( and kg haminus1) applied in each plot in the 2002 croppingseasons four village sites (Miniffi Gome Gbanlin and Akpero)Benin

Sitetreatment DM N P K N P Kt haminus1 kg haminus1 kg haminus1 kg haminus1

AkperoT0 41 17 02 05 684 78 212TM 35 13 01 05 453 52 174TMA 96 13 01 05 1259 141 476TMM 102 17 02 05 1778 202 539

GbanlinT0 40 10 02 05 422 60 207TM 35 23 02 06 785 81 221TMA 91 15 01 06 1323 93 566TMM 95 19 02 06 1804 143 611

MiniffiT0 43 09 02 06 411 67 276TM 37 19 01 06 707 48 221TMA 93 12 03 06 1148 261 597TMM 99 24 01 06 2396 149 632

GomeT0 40 09 01 05 364 50 196TM 35 25 01 06 869 26 222TMA 90 12 01 04 1049 54 342TMM 98 16 01 06 1601 67 601

the moulds along plot transects (32 farm fields times 4 treatmentstimes 2 depths = 256 samples)

Prior to ridging in four 1m2 quadrats within each plotthe aboveground biomass of herbaceous legumes and fallowwas collected inOctober 2002 and 2004Thebiomass sampleswere dried at 60∘C until constant weight and then dryweight was determined At maturity maize grain and stoverwere harvested per row on each plot and dry matter (DM)determined DM of yam tubers and shoots was estimated oneach plot in December 2003 and 2005 (Tables 2 and 3)

24 Soil and Plant Nutrients Content The nutrients contentsof the soil samples were performed in the Laboratory of SoilSciences Water and Environment (LSSEE) of INRAB (BeninNational Research Institute) The plant nutrient content wasestimated according to the biomass amount

Soil and plant macronutrients content (N P and K)were analyzed Nitrogen (N) content was analyzed usingthe Kjeldahl method [22] available phosphorus with Bray1 method [23] potassium with the FAO method [24 25]organic carbon with the Walkley and Black method [26]and soil fractionation with Robinson method [27] and pH(H2O) (using a glass electrode in 1 25 vv soil solution)

Only yam tuber and maize grain were removed and all otherplants parts were recycled (A gayanus maize stover yamshoot A histrix andM pruriens) Yam orM pruriens shootincluded leaves Nutrient removed or recycled was calculatedas a summation of nutrient concentration time dry matter of

Scientifica 5






GomeT0 40 09 01 05 363 50 195TM 35 25 01 06 865 26 222TMA 93 12 01 04 1079 56 352TMM 96 16 01 06 1573 66 591

the respective plant parts Dry matter removed or recycledwas calculated as a summation of dry matter of the respectiveplant parts

25 Analyses of Variance to Test the Effect of Site Year andTreatment on Yam Yield Analysis of variance (ANOVA)using the general linear model (GLM) procedure [28] wasapplied to the DM production (tubers and shoots) nutrientcontribution to the systems and soil properties at depths 0ndash10and 10ndash20 cm The experiment was conducted with 32 farm-ers eight in each site For each of them a randomized com-plete block design with four treatments and four replicateswas carried out using a partial nested model with five factorsYear Replicate Farmer Site and Treatment The randomfactorswere ldquoYearrdquo and ldquoReplicaterdquo and ldquoFarmerrdquo Farmerwasconsidered as nested within ldquoSiterdquo and ldquoReplicaterdquo as nestedwithin ldquoFarmerrdquo The fixed factors were ldquoTreatmentrdquo andldquoSiterdquo Sites were considered as fixed based on certain criteriasuch as landscape (lowland and plateau) soil type and initialsoil fertility Yield values were logarithmically transformedto normalize the data and to stabilize population varianceThe GLM was computed to assess the interactions betweenthe factors involved Least square means and standard errorwere also computed for factor levels and the Newman andKeuls test was applied for differences between treatmentsSignificance was regarded at 119875 le 005

3 Results

31 Initial Soil Characteristics The relevant general soilphysical and chemical characteristics before are presented inTable 4

Site physical characteristics such as soil texture (sand)were relatively high (74778ndash8879) followed by silt(555ndash1736) and clay (566ndash7861) with the lowestcontent The soils had a neutral reaction with pH (H2O)ranging from 63 to 68

The initial soil fertility status of different sites was low Soilorganic matter (SOM) contents were low in all fields rangingfrom 093 to 2258 and the C N ratio ranged from 869to 1170 Available P levels were very low and varied from3012 to 20125mgkg-soil Soil N concentration ranged from0056 to 0112 N P and SOM contents were significantlyhigher in 0ndash10 cm than in 10ndash20 cm depth except at Gbanlinsite for N and SOM Gome site showed for both soil depthsthe lowest values of carbon (C) N P (mgkg-soil) andorganic matter () whereas Akpero had the highest values

32 Dry Matter Production and Nutrient Contribution to theSystems In the 2002 and 2004 cropping seasons the highestbiomass dry matter (DM) amount recycled was recorded onTMM (Table 5)

The ANOVA partial nested model shows that yam yieldDM differed significantly depending on the factor Treatment(119875 lt 0001) The factors Site and Year were not significantfor yam yields DM But Replicate (119875 lt 0001) Treatmenttimes Farmer (119875 lt 001) and Year times Farmer interactions (119875 lt0001) were significant (Table 6)

Dry matter (t haminus1) of yam tubers removed and yamshoots recycled N P and K content (kg haminus1) dry matter ofplant parts removed in the crop harvest and those returnedto the soil in yam-based cropping systems were significantlyhigher in TMA and TMM than in T0 and TM during bothcropping seasons (Tables 7 and 8)

Therefore total plant N P and K (kg haminus1) dry matterremoved in the crop harvest and those returned to the soilin yam-based cropping systems were significantly higher inTMA and TMM than in T0 and TM during both croppingseasons (Table 9)

33 Effects of Treatments on Soil Characteristics Afterwardssoil characteristics at the end of the experiment globallyshowed relatively low clay silt and relatively high sand con-centration on different sites under different treatments (T0TM TMA and TMM) in comparison with initial soil char-acteristics at the beginning of the experiment Soil organicmatter concentration was improved at 10ndash20 cm depth par-ticularly in Miniffi (1247 1176 1326 and 1409) onT0 TM TMA and TMM respectively and Gome (10100959 1046 and 1126) Globally soil N and P concen-trations were improved on different sites on treatments TMAandTMM in 0ndash10 cmor 10ndash20 cmdepth (Tables 10(a)ndash10(d))

The end of study soil analysis showed soil chemicalproperties (SOM N P (mgkg-soil) K+ cmol kgminus1 andpH water) significantly higher in TMA and TMM than intraditional systems T0 and TM (119875 lt 0001) Soil clay contents

6 Scientifica

Table 4 Initial soil characteristics at the beginning of the experiment at 0ndash10 and 10ndash20 cm layers in four village sites (MiniffiGome Gbanlinand Akpero) with 32 farmers Benin

Akpero Gbanlin Miniffi GomeDepth (cm) 0ndash10 10ndash20 0ndash10 10ndash20 0ndash10 10ndash20 0ndash10 10ndash20

ldquoPlinthosolsrdquo ldquoPlinthosolsrdquo ldquoLuvisols ferriquesrdquo ldquoLuvisols ferriquesrdquoClay 658 7281 5788 566 6758 651 6828 7861Silt 1166 11798 5808 555 6828 7081 16071 1736Sand 8176 80920 88402 8879 86412 86408 7710 74778C 131 1050 069 0788 080 064 065 054N 0112 0092 0059 0081 0081 0056 0073 0062CN 1170 1143 1170 968 983 1143 890 869OM 225 181 119 136 137 110 112 093PH 67 67 66 63 67 68 66 66Bray P 20125 14875 700 400 1100 3012 7987 400C soil carbon concentration N soil nitrogen concentration OM (=172 times C) soil organic matter content CN index of biodegradability or ratio ofsoil carbon to nitrogen Bray P (mg kgminus1) soil phosphorus

Table 5 Dry matter (t haminus1) of plant parts returned to thesoil significantly increased according to four cropping systems(A histrixmaize intercropping-yam rotation M pruriensmaizeintercropping-yam rotation 1-year fallow of Andropogon gayanus-yam rotation maize-yam rotation) during the 2002 and 2004cropping seasons in four villages in Benin

Cropping system Cropping season 2002 Cropping season 2004DM (t haminus1) DM (t haminus1)

T0 41c 39c

TM 35d 32d

TMA 92b 83b

TMM 97a 88a

Means with the same letter within row are not significantly different (119875 gt005)T0 (control 1) one-year fallow-yam rotation TM (control 2) maize-yamrotation TMA A histrixmaize intercropping-yam rotation TMM Mpruriensmaize intercropping-yam rotation DM dry matter

were significantly higher in TMA TMM and T0 than inTM (119875 lt 0001) No significant difference was observedfor silt and sand concentrations for different treatments(Table 10(e))

4 Discussion

41 DryMatter andNutrients Recycled in Yam-BasedCroppingSystems Thehighest biomass drymatter (DM) amount recy-cled was recorded on Mucunamaize intercropping (TMM)Mucuna grows rapidly and DM production can reach10 t haminus1 [2 17 29] In factMucuna creeps and climbs maizestraw in pattern crop allowing the lianas staking ThereforeMucuna large leaves profit from solar radiations improv-ing the photosynthetic activity and the plant productivityMucuna reaches the physiological maturity (flowering time)between 180 and 240 days after grains planting in the studyarea in comparison with Aeschynomene (200ndash306 days) [3031]

DM of yam shoots recycled on TMA and TMM weresignificantly higher in 2005 (dry year) than in 2003 (humidyear) The chemical fertilizers applied and the above biomassDM of intercropping maize and herbaceous legume recycledand accumulated in 2002 2003 and 2004 could have resultedin a combined beneficial effect of water nutrient use andplant growth in 2005 DM amounts of M pruriens Ahistrix and maize stover recycled were higher in 2002-2003 (humid year) than in 2004-2005 (dry year) In factplant yields and agronomic productivity were constrained byrecurring drought stress exacerbated by highly variable andunpredictable rains M pruriens stover showed the highestDM amount followed by A histrix whatever the year and thiscould reach 10 t haminus1 [18] becauseMPruriens comparedwithA histrix grows more rapidly and close

The nutrient (N P and K) levels removed or recycledfit the DM production (tubers and shoots) and then variedaccording to treatment and cropping season

42 Impact of Yam-Based Cropping Systems with HerbaceousLegumes on Soil Properties Most of the soils as mentionedabove are tropical ferruginous soils originally from Precam-brian crystalline rocks (granite and gneiss) and classifiedas plinthosols (Gbanlin and Akpero) and luvisols (Miniffiand Gome) Miniffi and Akpero are located on a plateau(well-drained soils) while Gome is on lowland (more poorlydrained soils) Gbanlin is located on an undulating plateauwith concretions Soil chemical analysis showed that the soilwas deficient in N P and K and soil organic matter (SOM)This could be due to the mining agriculture and also a con-sequence of the mechanical destruction of the soil structureduring the ridging for yam crop In fact yam is a demandingcrop in terms of organic matter and nutrients Research [32]reported that yam yielding about 30 t of fresh tuber haminus1removes 120N kg haminus1 51 P kg haminus1 and 111 K kg tminus1 Whenland is used too intensively the SOM is rapidly reducedin the unstable fraction In the short and medium termthis reduction leads to a decrease in soil biological activity

Scientifica 7

Table 6 ANOVA partial nestedmodel of the effect of the four treatments on logarithmic transformed values of drymatter yields of ldquoKokorordquoyam (Dioscorea rotundata) (2002-2003 and 2004-2005 4 sites 32 farmers Benin)

Source DF Adj SS Adj MS 119865 119875

Site 3 04258 01419 lowastlowast

Farmer (Site) 28 34833 01244 018 1000Replicate (Site) 96 423111 35259 27 0000Year 1 00002 00002 001 0943Treatment 3 2240376 746792 534406 0000Site times Treatment 9 00291 00032 011 0999Treatment times Farmer (Site far) 84 22389 00267 162 0001Year times Farmer (Site) 28 6933 02476 1502 0000Year times Treatment 3 00114 00038 02 0892Year times Site 3 0141 0047 019 0904Year times Site times Treatment 9 01685 00187 114 0334Error 756 124598 00165Adjusted 119877-square () 9424DF degree of freedom Adj SS adjusted sums of squares Adj MS adjusted mean squares 119865 Fisherrsquos test 119875 Fisherrsquos probability testlowastlowastDenominator of 119865-test is zero

Table 7 Dry matter (t haminus1) of yam tubers removed and yam shoots recycled in the 2002-2003 and 2004-2005 cropping seasons in fourvillages in Benin

2002-2003 cropping seasons 2004-2005 cropping seasonsT0 TM TMA TMM LSD T0 TM TMA TMM LSD

Yam DM removed (t haminus1)DM removed 509b 383c 720a 733a 051 434b 302c 800a 802a 055

Yam shoots DM recycled (t haminus1)Yam shoots 127b 096c 180a 183a 013 109b 076c 200a 200a 014Means with the same letter within row are not significantly different (119875 gt 005)DM dry matter LSD least square difference at 5T0 (control 1) one-year fallow-yam rotation TM (control 2)maize-yam rotation TMAA histrixmaize intercropping-yam rotation TMMM pruriensmaizeintercropping-yam rotation

and then contributes to soil degradation and depletion [33]Many studies report that soil organicmatter (SOM) decreasesin cultivated soils [33] This decrease is linked to the depth ofthe cultivated soil layer and is probably exacerbated in yam-based cropping systems

Nitrogen is the most deficient component of these soilsgrown with low organic matter content Total nitrogendeficiency of these soils lies in the fact that nitrogen is the onlymajor nutrient that does not exist in the bedrock Furtherthe transfer of atmospheric nitrogen to the soil by biologicaland chemical process is slow Losses of nitrogen in thesesoils are common because of the high volatility and solubilityof this nutrient Nitrogen is generated by the breakdown ofinherent organic matter and needs to be supplemented withother sources of organic materials or mineral fertilizer Manystudies focusing on these elements conclude that there is anindisputable need to correct the lack of N and P in the soil inAfrica [2 6]

It is possible to reduce or stop ongoing soil degradationand the decrease in yield with such rotations includingimproved short fallows or intercropping with herbaceouslegumesThe use of legumes improves levels of concentration

of the soil parameters The improvement of the clay con-centration at the end of the perennial experiment could bedue to the process of the composite soil samples collectedon the ridges resulting from the brewing of the soil deeplayer relatively rich in clay and the soil horizon surface afterridging Indeed ridging allows increasing the volume of thesoil deep layer and contributes to the incorporation of organicresidues into the soil

Significant differences in total SOM and nutrientsincrease with treatments TMAandTMM in comparisonwithT0 and TM could be due to the faster decomposition offermentable green manure (herbaceous legumes) with lowhumification coefficient (5) added to the moderate decom-position of lignified maize stover on relatively degraded soils[34] Our observations are in agreement with those of [35]who reported that cropping systems and organic manureshave the most influence on the SOM Rotations with Mpruriens andA histrix represented a source of easily availableN P and K for the yam crop which could be related to theirfaster decomposition and nutrient release comparedwith theslower release of nutrients by poorer quality materials suchas maize stover and A gayanus grass In Ghana studying the

8 Scientifica

Table 8 Nitrogen phosphorus and potassium content (kg haminus1) dry matter of plant parts removed in the crop harvest and those returnedto the soil in yam-based cropping systems (2002-2003 and 2004-2005 cropping seasons four cropping system treatments four village sites32 farmers Benin)

2002-2003 cropping seasons 2004-2005 cropping seasonsT0 TM TMA TMM LSD SD T0 TM TMA TMM LSD SD

Plant nutrients removed (kg haminus1)

Yam tubersN 1935b 1457c 2737a 2784a 195 298 1649b 1148c 3041a 3047a 208 318P 199b 149c 281a 286a 020 031 169b 118c 312a 313a 021 033K 2139b 1610c 3025a 3077a 216 330 1823b 1270c 3361a 3368a 230 352

Maize grainsN 000b 3488a 3443a 3338a 227 347 000c 3152a 2768b 2671b 203 311P 000b 530a 524a 508a 035 053 000c 479a 421b 406b 031 047K 000b 434a 428a 415a 028 043 000c 392a 344b 332b 025 039

Plant nutrients recycled (kg haminus1)

Yam shootsN 1401b 1054c 1981a 2015a 141 216 1172b 816c 2160a 2165a 148 226P 191b 144c 270a 275a 019 029 130b 091c 240a 241a 016 025K 1757b 1322c 2485a 2528a 177 271 1465b 1020c 2701a 2706a 185 283

Fallow stoverN 4763a 000b 000b 000b 386 591 4703a 000b 000b 000b 422 646P 526a 000b 000b 000b 123 189 509a 000b 000b 000b 127 194K 1990a 000b 000b 000b 216 330 1949a 000b 000b 000b 198 303

Maize stoverN 000b 3187a 3143a 3047a 245 375 000c 3345a 2935b 2828b 260 397P 000b 456a 451a 437a 039 060 000c 465a 408b 395b 045 068K 000c 1748ab 1857a 1676b 186 284 000c 1742a 1530b 1480b 142 217

Aeschy stoverN 000b 000b 11593a 000b 663 1014 000b 000b 10770a 000b 934 1428P 000b 000b 815a 000b 097 149 000b 000b 876a 000b 069 105K 000b 000b 3625a 000b 133 203 000b 000b 3453a 000b 170 260

Mucuna stoverN 000b 000b 000b 13892a 653 999 000b 000b 000b 13325a 528 807P 000b 000b 000b 1140a 181 277 000b 000b 000b 1111a 161 246K 000b 000b 000b 3973a 151 231 000b 000b 000b 3968a 178 272

Means with the same letter within row are not significantly different (119875 gt 005)T0 (control 1) one-year fallow-yam rotation TM (control 2)maize-yam rotation TMAA histrixmaize intercropping-yam rotation TMMM pruriensmaizeintercropping-yam rotation SD standard deviation LSD least square difference at 5

Table 9 Total plant nitrogen phosphorus and potassium (kg haminus1) dry matter removed in the crop harvest and those returned to the soilin yam-based cropping systems (2002-2003 and 2004-2005 cropping seasons four cropping system treatments four village sites 32 farmersBenin)


Total nutrients removalthrough harvest(kg haminus1)

N 1935c 4944b 6180a 6122a 291 446 1649c 4301b 5809a 5718a 290 444P 199c 680b 805a 793a 039 060 169c 597b 733a 719a 038 057K 2139b 2044b 3453a 3493a 216 330 1823b 1661b 3705a 3700a 231 354

Total nutrients recycledthrough plant biomass(kg haminus1)

N 6164c 4241d 16717b 18954a 1068 1633 5875c 4161d 15866b 18317a 1159 1772P 717c 600c 1536b 1852a 221 337 640c 556c 1525b 1747a 209 320K 3747b 3071c 7966a 8177a 324 495 3414c 2762d 7684b 8154a 394 603

Means with the same letter within row are not significantly different (119875 lt 005)T0 (control 1) one-year fallow-yam rotation TM (control 2)maize-yam rotation TMAA histrixmaize intercropping-yam rotation TMMM pruriensmaizeintercropping-yam rotation SD standard deviation LSD least square difference at 5

Scientifica 9

Table 10 (a) Soil characteristics at the end of the experiment (December 2005) 0ndash10 and 10ndash20 cm layers on 1-year fallow of Andropogongayanus-yam rotation (T0) 32 farmers four village sites Benin (b) Soil characteristics at the end of the experiment (December 2005) 0ndash10and 10ndash20 cm layers on maize-yam rotation (TM) 32 farmers four village sites Benin (c) Soil characteristics at the end of the experiment(December 2005) 0ndash10 and 10ndash20 cm layers on A histrixmaize intercropping-yam rotation (TMA) 32 farmers four village sites Benin(d) Soil characteristics at the end of the experiment (December 2005) 0ndash10 and 10ndash20 cm layers on M pruriensmaize intercropping-yamrotation (TMM) 32 farmers four village sites Benin (e) Soil characteristics at the end of the experiment (December 2005) 0ndash10 and 10ndash20 cm layers four yam-based cropping systems (1-year fallow of Andropogon gayanus-yam rotation maize-yam rotation A histrixmaizeintercropping-yam rotationM pruriensmaize intercropping-yam rotation) 32 farmers four village sites Benin (all sites confounded)

(a)


ldquoPlinthosolsrdquo ldquoPlinthosolsrdquo ldquoLuvisols ferriquesrdquo ldquoLuvisols ferriquesrdquoClay 5927 6101 5276 5227 6078 6143 6004 6239Silt 10482 10755 5425 5446 6329 6568 15950 16089Sand 83587 83143 89293 89325 87587 87287 78046 77671C 0996 0909 0686 0672 0756 0723 0625 0587N 0080 0087 00575 0059 0061 0061 00588 0058CN 12523 10911 1200 11389 12438 11928 10821 10211OM 1713 1563 1180 1157 1301 1247 1076 1010PH 6364 6095 6020 6278 5934 6020 5934 5848Bray P 20440 18880 5646 5743 9073 6688 5668 3693K 0385 0366 0407 0283 0329 0214 0203 0201C soil carbon concentration N soil nitrogen concentration OM (=172 times C) soil organic matter content CN index of biodegradability or ratio ofsoil carbon to nitrogen Bray P (mgkg-soil) soil phosphorus K cmol kgminus1 soil potassium

(b)



(c)


ldquoPlinthosolsrdquo ldquoPlinthosolsrdquo ldquoLuvisols ferriquesrdquo ldquoLuvisols ferriquesrdquoClay 6509 6752 5455 5999 6245 5882 5567 5390Silt 10581 10811 5513 5608 6310 6396 1585 15866Sand 82 910 82438 89033 88394 87445 87721 78748 78744C 11248 10583 0732 0685 0781 0771 0635 0608N 0107 0124 0073 0084 0084 0092 0079 0076CN 10707 8654 10115 8197 9300 8417 8082 8006OM 1935 1820 1260 1178 1344 1326 1092 1046PH 7371 7221 7112 7237 7034 7087 6997 7031Bray P 23890 22930 8929 8540 9364 6900 9364 6900K 0687 0604 0509 0436 0452 0297 0332 0298C soil carbon concentration N soil nitrogen concentration OM (=172 times C) soil organic matter content CN index of biodegradability or ratio ofsoil carbon to nitrogen Bray P (mgkg-soil) soil phosphorus K cmol kgminus1 soil potassium

10 Scientifica

(d)



(e)

Soil characteristics Depth T0 TM TMA TMM LSD

Clay 0ndash10 cm 5821c 5519d 5944b 5959a 011110ndash20 cm 5928c 5611d 6006b 6054a 0124

Silt 0ndash10 cm 9546a 9678a 9522a 9530a ns10ndash20 cm 9714a 9807a 9670a 9645a ns

Sand 0ndash10 cm 84628a 84802a 84534a 84511a ns10ndash20 cm 84357a 84584a 84324a 84301a ns

C 0ndash10 cm 0766b 0764b 0818b 0869a 003710ndash20 cm 0723b 0703b 0780a 0827a 0033

N 0ndash10 cm 0064d 0076c 0086b 0095a 000310ndash20 cm 0066c 0085b 0094a 0099a 0004

C N 0ndash10 cm 11947a 10087b 9551c 9032c 027210ndash20 cm 11109a 8309b 8319b 8343b 0211

MO 0ndash10 cm 1317b 1313b 1408a 1495a 006310ndash20 cm 1244c 1209c 1342b 1422a 0057

Bray P (mg kgminus1) 0ndash10 cm 10210c 11840b 13430a 14346a 112610ndash20 cm 8750c 10660b 11410ab 12290a 1217

K+ cmol kgminus1 0ndash10 cm 0331d 0424c 0495b 0536a 002610ndash20 cm 0266d 0330c 0409b 0453a 0028

PH water 0ndash10 cm 6063c 6688b 7129a 7031a 005510ndash20 cm 6060c 6680b 7144a 6984a 0053

Means with the same letter within row are not significantly different (119875 gt 005)C soil carbon concentration N soil nitrogen concentration OM (=172 times C) soil organic matter content C N ratio of soil carbon to nitrogen BrayP (mgkg-soil) soil phosphorus K+ cmol kgminus1 soil potassium LSD least square difference at 5 SD standard deviationT0 (control 1) one-year fallow-yam rotation TM(control 2)maize-yam rotation TMAA histrixmaize intercropping-yam rotation TMMMpruriensmaizeintercropping-yam rotation LSD least square difference at 5 ns nonsignificantData are the means

effect of cropping sequences with cassava and legume crops[36] indicated that only 30 ofM pruriens litter remained sixweeks after incorporation of the biomass References [37] and[38] that studied the traditional M pruriens-maize rotationin Honduras estimated that 83 of nitrogen produced by amulch of M pruriens was available for the following maizecropThey also observed that available P remained practicallyconstant with 15 to 20mgkg-soil in the surface horizon inspite of P exports by maize Reference [38] concluded thatthe practice of continued rotationwithM pruriens andmaizeprevented soil N depletion for at least 15 years

Our results showed that legumes improved soil PLegumes fallows with M pruriens are known especially forimproving the quantity of available P fractions in the soilfor subsequent crops [39] Nevertheless they depend on theinherent P levels in the soilsM pruriens root exudates couldsolubilize P increasing its availability In the study of [40]organic materials have also been found to reduce P sorptioncapacity of soils and increase crop yields in P limiting soils

The soil K concentrations were improved in our study(Table 4) Reference [3] showed soil K concentration of082 cmol kgminus1 in the 0ndash20 cm soil layer and decreasing

Scientifica 11

significantly with cultivation The rate of decline was about0023ndash0054 cmol kgminus1 yearminus1 in the 0ndash20 cm soil layer [3]

5 Conclusions

The field of interest of the study is to determine the impactof yam-based systems with herbaceous legumes on drymatter production (tubers and shoots) nutrients removedand recycled and the soil fertility changes Yam tuberdry matter production was significantly improved in yam-based systems with legumes in comparison with traditionalsystems Treatment times Farmer and Year times Treatment inter-actions influenced significantly the yam tuber dry matterproduction Amounts of N P and K recycled in yam shootwere significantly higher in yam-based systems with legumesthan in traditional systems The nutrient (N P and K) levelsremoved or recycled fit the DM production (tubers andshoots) and then varied according to treatments and croppingseasons The end of study soil analysis showed soil chemicalproperties (SOM N P (mgkg-soil) K+ cmolkg and pHwater) significantly higher in treatments with legumes thanin traditional systems We then propose to promote durableand replicable yam-based systems with legumes through afavorable legislative economic and political environmentto support local initiatives Collaborations between farmersresearch development and extension structures should alsobe favored to support the development and dissemination ofinnovations

Competing Interests

The authors declare that there is no conflict of interestsregarding the publication of this paper

Acknowledgments

The authors express their sincere appreciation and thanksfor the Cooperation Program for Academic and ScientificResearch (CORUS) Finally the authors greatest appreciationgoes to farmers who freely agreed to participate in trials andmake part of their fields available for the research

References

[1] FAO (Food and Agriculture Organization) ldquoFAOndashUNESCOsoil map of the world Revised legendrdquo Soils Bulletin 60 FAORome Italy 1990

[2] A H Azontonde ldquoDegradation et restauration des terres debarre (sols ferrallitiques faiblement desatures argilo-sableux) auBenin La gestion conservatoire de lrsquoeau de la biomasse et de lafertilite des sols (GCES)rdquo cah Orstom Ser Pedol vol 28 no 2pp 217ndash226 1993

[3] A M IgueThe use of the soil database for land evaluation pro-ceduresmdashcase study of central Benin [PhD thesis] University ofHohenheim Stuttgart Germany 2000

[4] D Cornet P Vernier F Amadji and R Asiedu ldquoIntegrationof yam in cover crop based cropping system constraints andpotentialrdquo in Proceedings of the 14th Triennial Symposium ofthe International Society for Tropical Root Crops (ISTRC rsquo06)Central Tuber Crops Research Institute ThiruvananthapuramIndia 2006

[5] L Herrmann Staubdeposition auf Boden West Africas Eigen-schaften und Herkunftsgebiete der Staaube und ihr Einfluszlig aufBoden und Standortseigenschaften Hohenheimer Bodenk Hefte36 Hohenheim University Stuttgart Germany 1996

[6] T Gaiser B Fadegnon M Cretenet and C Gaborel ldquoLong-term experience on a tropical Acrisol evolution of soil prop-erties and yieldrdquo UFZmdashBerichte vol 24 pp 153ndash156 1999

[7] S Hauser ldquoBiomass production nutrient uptake and partition-ing in planted Senna spectabilis Flemingia macrophylla andDactyladenia barteri fallow systems over three fallowcroppingcycles on Ultisolrdquo in Paper Presented at Tropentag BonnGermany October 2006

[8] J Gockowsky J Tonye D Baker et al ASB Report Phase IIMarch 1999 IITAIRAD Yaounde Cameroon 2002

[9] I C Onwueme and A J Haverkort ldquoModelling growth andproductivity of Yams (Dioscorea Spp) prospects and problemsrdquoAgricultural Systems vol 36 no 3 pp 351ndash367 1991

[10] FAO FAOSTAT Crop Production Data 2009 httpfaostatfaoorg

[11] R J Carsky M Becker and S Hauser ldquoMucuna cover cropfallow systems potential and limitationsrdquo in Sustaining SoilFertility in West Africa G Tian F Ishida and J D H KeatingeEds vol 58 of SSSA Special Publication pp 111ndash135 SoilScience Society ofAmerica andAmerican Society ofAgronomyMadison Wis USA 2001

[12] P Vernier andRADossou ldquoAdaptation of yam (Dioscorea spp)cultivation to changing environment and economic constraintsin Benin Africardquo in Proceedings of the 12th Symposium of theInternational Society for Tropical Root Crops (ISTRC rsquo00) pp352ndash359 Tsukuba Japan September 2000

[13] S Doumbia ldquoRevue de la bibliographie sur le theme de lasedentarisation de la culture de lrsquoigname en Afrique de lrsquoOuesta travers le cas du Beninrdquo FAOMAEPINRAB 2005

[14] R Maliki Sedentarisation de la culture drsquoigname et gestiondurable des ressources naturelles dans la region centre du Benindeveloppement participatif contraintes adoption et diffusion destechnologies [These DEA] University of Abomey-Calavi (UAC)Abomey-Calavi Benin 2006

[15] A Saıdou Converging strategies by farmers and scientist toimprove soil fertility and enhance crop production in Benin [PhDthesis] Wageningen University Wageningen The Netherlands2006

[16] J N OrsquoSullivan and J Ernest Yam Nutrition and Soil FertilityManagement in the Pacific ACIAR Canberra Australia 2008

[17] R J Carsky S A Tarawali M Becker D Chicoye G Tian andN SangingaMucuna A Herbaceous Cover Legume with Poten-tial for Multiple Use vol 25 of Resource and Crop ManagementDivision (RCMD) ResearchMonographs International Instituteof Tropical Agriculture Ibadan Nigeria 1998

[18] M Becker D E Johnson and Z J Segda ldquoThe role of legumefallows in intensified unpland rice-based systems of WestAfricardquo in Cover Crops in West Africa Contributing to Sustain-able Agriculture D Buckles A Eteka O Osiname M Galibaand G Galiano Eds pp 85ndash108 International DevelopmentResearchCentre International Institute of Tropical AgricultureSasakawa Global 2000 Cotonou Benin 1999

[19] D Dubrouecq Etude des Sols de la Region Ouest Dassa-Zoumevol 96 of Etude CENAP Benin 1977

[20] V Agossou and M Igue Caracterisation des Sols des Sites deRecherche Developpement du Cra-Centre Classification Dans laBase de Reference Mondiale et Actualisation de Leur Niveau

12 Scientifica

de Degradation CRA- Centre INRABMAEP Save Benin 1stedition 2002

[21] P Vernier and R A Dossou ldquoAn example of sedentarization ofyam cultivation The case of Kokoro varieties in the Republicof Beninrdquo Agronomie Africaine vol 15 no 4 pp 187ndash196 2003Atelier national sur le developpement durable de la productionet de la consommation de lrsquoigname en Cote drsquoIvoire 2001-10-232001-10-26 Abidjan Cote drsquoIvoire

[22] H Scarf ldquoOne hundred years of the Kjeldahl method fornitrogen determinationrdquoArchiv fur Acker- undPflanzenbau undBodenkunde vol 32 pp 321ndash332 1988

[23] R H Bray ldquoA nutrient mobility concept of soil-plant relation-shipsrdquo Soil Science vol 78 no 1 pp 9ndash22 1954

[24] FAO A Standard Guide to Soil Fertility Investigations in FanersrsquoFields Soils Bulletin no 11 FAO Rome Italy 1970

[25] FAO Soil and Plant Testing and Analysis Soils Bulletin no 381FAO Rome Italy 1977

[26] A Walkley and I A Black ldquoAn examination of the Degtjareffmethod for determining soil organic matter and a proposedmodification of the chromic acid titrationmethodrdquo Soil Sciencevol 37 no 1 pp 29ndash38 1934

[27] GW Robinson Soils Their Origin Constitution and Classifica-tion Thomas Murby amp Co London UK 2nd edition 1936

[28] SAS Institute SAS Userrsquos Guide Statistics SAS Institute CaryNC USA 1996

[29] R Lal ldquoTillage and mulching effects on maize yield for seven-teen consecutive seasons on a tropical Alfisolrdquo Journal of Sus-tainable Agriculture vol 5 no 4 pp 79ndash93 1995

[30] R Maliki M Toukourou F Amadji and I Adje ldquoReferentieltechnico-economique sur la production durable de lrsquoigname dequalite dans un systeme de cultures integrant lrsquoAeschynomenehistrixrdquo Tech Rep FAOTCPBEN3002 (A) INRABMAEPCotonou Benin 2007

[31] R Maliki M Toukourou F Amadji and I Adje ReferentielTechnico-Economique sur la Production Durable de lrsquoIgnamede Qualite Dans un Systeme de Cultures Integrant le Mucunapruriens var utilis FAOTCPBEN3002 (A) INRABMAEPCotonou Benin 2007

[32] L Degras ldquoThe yam a tropical root croprdquo in AgriculturalTechnic and Tropical Production Maisonneuve and LaroseParis France 1986

[33] MQuenumMGiroux andR Royer ldquoEtude sur le bilan humi-que des sols dans des systemes culturaux sous prairies et souscultures commerciales selon lesmodes de fertilizationrdquoAgrosolvol 15 no 2 pp 57ndash71 2004

[34] French Ministry of Cooperation Memento de lrsquoAgronomeFrench Ministry of Cooperation 1993

[35] MA BolinderContribution aux connaissances de la dynamiquedu C dans les systemes SOL-PLANTE de lrsquoEst du Canada [PhDthesis] Universite Laval 2003

[36] S Adjei-Nsiah T W Kuyper C Leeuwis M K Abekoe andK E Giller ldquoEvaluating sustainable and profitable croppingsequences with cassava and four legume crops effects on soilfertility and maize yields in the forestsavannah transitionalagro-ecological zone of Ghanardquo Field Crops Research vol 103no 2 pp 87ndash97 2007

[37] M van Noordwijk T P Tomich R Winahyu D MurdiyarsoS Partoharjono and A M Fagi EdsAlternatives to Slash-and-Burn in Indonesia Summary Report of Phase 1 Alternatives toSlash-and-Burn Agriculture (ASB)-Indonesia Report No 4 ASB-Indonesia Consortium and ICRAF Bogor Indonesia 1995

[38] B L Triomphe Seasonal nitrogen dynamics and long-termchanges in soil properties under the Mucunamaize cropping sys-tem on the hillsides of northern Honduras [PhD dissertation]Cornell University Ithaca NY USA 1996

[39] F K Salako and G Tian ldquoManagement of a degraded Alfisolfor crop production in southwestern Nigeria effects of fallowmounding and nitrogenrdquo Journal of Sustainable Agriculture vol22 no 2 pp 3ndash22 2003

[40] G Nziguheba C A Palm R J Buresh and P C Smithson ldquoSoilphosphorus fractions and adsorption as affected by organic andinorganic sourcesrdquo Plant and Soil vol 198 no 2 pp 159ndash1681998

Submit your manuscripts athttpwwwhindawicom

Nutrition and Metabolism

Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014


Food ScienceInternational Journal of

Agronomy


International Journal of



Microbiology

The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom

Applied ampEnvironmentalSoil Science

Volume 2014

AgricultureAdvances in


PsycheHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

BiodiversityInternational Journal of


ScientificaHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

GenomicsInternational Journal of


Plant GenomicsInternational Journal of


Biotechnology Research International


Forestry ResearchInternational Journal of


Journal of BotanyHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

EcologyInternational Journal of


Veterinary Medicine International


Cell BiologyInternational Journal of


Evolutionary BiologyInternational Journal of


2 Scientifica

can no longer continue inmost of humid Sub-SaharanAfricaIncreasing population densities are posing a serious threatto natural resources and agricultural production Farmersrsquoresponse to higher food demand has been either an increasein cultivated area or a reduction of fallow period Theminimum fallow duration to maintain crop production wasestimated at 12 years [7] Fallow periods in most of the humidzone of West and Central Africa are actually between 2 and5 years [8] reinforcing the need to seek alternative foodproduction systems [7]

Yam (Dioscorea spp) is a tuber crop widely cultivatedin the humid and subhumid lowland regions of West Africaand the Caribbean [9] More than 90 of the worldwideproduction (40 Mt fresh tubersyear) is produced in WestAfrica [10] Yam is grown in traditional cropping systemsas the first crop after land clearance yielding about 10 t offresh tuberhayear [11] but when the soil fertility is high itcan easily reach 25ndash30 tha in farm fields [12] with Dioscoreacayenensis-rotundata varieties In Benin nowadays farmershardly have the possibility to rely on long duration fallow andyam is being cultivated in 1- or 2-year herbaceous fallow ormaize rotation systems with manual incorporation of residueinto the soil [13 14] Smallholder farmers removed importantquantities of nutrient from their soil without applying a suffi-cient quantity ofmanure or fertilizer to replenish the soil [15]

Yam cultivation in West Africa is now confronted withthe scarcity of fertile soil available for clearing [4] In Beninnowadays farmers hardly have the possibility to rely onlong duration fallow and yam is being cultivated in 1- or 2-year herbaceous fallow-yam or maize-yam rotation systemswith manual incorporation of residue into the soil [1314] Smallholder farmers removed important quantities ofnutrient from their soil without applying a sufficient quantityof manure or fertilizer to replenish the soil [15]

The decline in yam yields under continuous cultivationhas led to the largely accepted conclusion that yam requiresa high level of natural soil fertility (organic matter andnutrient) [16] Since the demand for yam keeps increasingdue to the continued population growth reserves of arableland are diminishing and fallow duration is decreasing It isbecoming necessary to sustainably increase yam productivityin sedentary cropping systems [16] There is a dire needtherefore to assess in farmersrsquo conditions the economicperformance of sustainable cultivation techniques Ongoingsoil degradation could be reduced by the adoption of newfarming techniques such as improved fallows of herbaceouslegumes [17 18]

Studies on improved fallow practices are generally grain-oriented (cereals such as maize) whereas very little hasbeen done on root and tuber crops especially yam Com-parative studies are lacking that assess the effects of yam-based technologies with herbaceous legumes intercrops andshort fallows on yam production and soil properties inthe savannah transition agroecological zone of Benin Wecompared in a perennial experiment for 4 years with 2-yearrotations smallholder farmersrsquo traditional rotations maize-yam or 1-yearAndropogon gayanus fallow-yamwith rotationsintercropped Aeschynomene histrix with maize-yam or inter-cropped Mucuna pruriens with maize-yam The objective of

Figure 1 Study area location in the savannah transitional agroeco-logical zone of Benin

this study was to determine the impact of yam-based systemswith herbaceous legumes on dry matter (DM) production(tubers and shoots) nutrients removed and recycled and thesoil fertility changes

2 Materials and Methods

21 Study Sites The study was carried out in the Guinea-Sudan transition zone of Benin (centre of Benin) in four sitesMiniffi (District of Dassa-Zoume) Gome (Glazoue) Akperoand Gbanlin (Ouesse) with latitudes 7∘451015840 and 8∘401015840 northand longitudes 2∘201015840 and 2∘351015840 east (Figure 1)

The climate is tropical transitional Guinea-Sudan with arainfall distribution gradient from bimodal (Southern Benin)tomonomodal (Northern Benin)The average annual rainfallduring the study period was 1052mm (2002) 1386mm(2003) 983mm (2004) and 797mm (2005) The rainfallregime in the study area is variable and unequal distribution(ie number of rainy days per month) varies from one siteto another The 2002 and 2003 cropping seasons were wetand had better rainfall distribution with an average annualprecipitation of 1200mm whereas 2004 and 2005 were dry(890mm) with relatively low rainfall distribution

Most of the soils are tropical ferruginous soils [19] origi-nally fromPrecambrian crystalline rocks (granite and gneiss)and classified as plinthosols (Gbanlin and Akpero) and luvi-sols (Miniffi and Gome) [20] (Table 1) Miniffi Akpero andGbanlin are located on a plateau while Gome is on lowlandAkpero is close to forest whileGbanlinMiniffi andGome arefar There is a rising gradient of fertility from the continuouscropping system on degraded soils towards the forests Thisdegradation is related to soil organic matter decrease whichleads to nutrient depletion (nutrients removed in the cropharvest leaching and erosion) Vegetation is a degradedwoody savannah type Maize yam cassava and groundnutare annual cropping systems and the cash crops are cottonand soybean Mineral fertilizer application appears to beessential Smallholder farmers use fertilizers on maize ondepleted soils depending on cash and inputs availabilityCotton is not mixed cropping but pure crop in rotation withother crops (maize or sorghum)

Scientifica 3

Table1Cr

opping

calend

arof

yam-based

crop

ping

syste

msw

ithherbaceous

legumes

andshortfallowin

the2

002-2003

and2004-2005crop

ping

season

s

Dec

Jan

Feb

March

April

May

June

July

Aug

Sept

Oct

Nov

Dec

2002

or2004

cropping

seasons

T0Naturalfallo

wof

Andropogon

gayanu

sSlashing

andbiom

assincorpo

ratio

n(ridging

)

TMLand

slashingand

plou

ghing

Maize

plantin

gNPK

application

andweeding

Weeding

and

urea

application

Maize

harvestin

gSlashing

andbiom

assincorpo

ratio

n(ridging

)infurrow

TMA

Land

slashingand

plou

ghing

Maize

plantin

gNPK

application

Ahistr

ixplantin

gandweeding

Weeding

and

urea

application

Maize

harvestin

gSlashing

andbiom

assincorpo

ratio

n(ridging

)infurrow

TMM

Land

slashingand

plou

ghing

Maize

plantin

gNPK

application

andweeding

Mucun

aplantin

g

Weeding

and

urea

application

Maize

harvestin

gSlashing

andbiom

assincorpo

ratio

n(ridging

)infurrow

2003

or2005

cropping

season

T0Seed

yam

plantin

gmou

ndsc

apping

with

mulch

material

yam

staking

and

weeding

Weeding

Weeding

Yam

harvestin

g

TMSeed

yam

plantin

gmou

ndsc

apping

with

mulch

material

yam

staking

and

weeding

Weeding

Weeding

Yam

harvestin

g

TMA

Seed

yam

plantin

gmou

ndsc

apping

with

mulch

material

yam

staking

and

weeding

Weeding

Weeding

Yam

harvestin

g

TMM

Seed

yam

plantin

gmou

ndsc

apping

with

mulch

material

yam

staking

and

weeding

Weeding

Weeding

Yam

harvestin

g


rotatio

nTM

maize-yam

rotatio

nTM

AA

eschynom

eneh

istrix

maize

intercropp

ing-yam

rotatio

nTM

MM

ucun

aprurien

smaize

intercropp

ing-yam

rotatio

n

4 Scientifica














GomeT0 40 09 01 05 364 50 196TM 35 25 01 06 869 26 222TMA 90 12 01 04 1049 54 342TMM 98 16 01 06 1601 67 601






Scientifica 5






GomeT0 40 09 01 05 363 50 195TM 35 25 01 06 865 26 222TMA 93 12 01 04 1079 56 352TMM 96 16 01 06 1573 66 591



3 Results










6 Scientifica






T0 41c 39c

TM 35d 32d

TMA 92b 83b

TMM 97a 88a



4 Discussion





Scientifica 7














8 Scientifica




















Scientifica 9


(a)



(b)



(c)



10 Scientifica

(d)



(e)
















Scientifica 11


5 Conclusions


Competing Interests


Acknowledgments


References





















12 Scientifica
























Journal of




Agronomy





Microbiology




Volume 2014
























Scientifica 3

Table1Cr

opping

calend

arof

yam-based

crop

ping

syste

msw

ithherbaceous

legumes

andshortfallowin

the2

002-2003

and2004-2005crop

ping

season

s

Dec

Jan

Feb

March

April

May

June

July

Aug

Sept

Oct

Nov

Dec

2002

or2004

cropping

seasons

T0Naturalfallo

wof

Andropogon

gayanu

sSlashing

andbiom

assincorpo

ratio

n(ridging

)

TMLand

slashingand

plou

ghing

Maize

plantin

gNPK

application

andweeding

Weeding

and

urea

application

Maize

harvestin

gSlashing

andbiom

assincorpo

ratio

n(ridging

)infurrow

TMA

Land

slashingand

plou

ghing

Maize

plantin

gNPK

application

Ahistr

ixplantin

gandweeding

Weeding

and

urea

application

Maize

harvestin

gSlashing

andbiom

assincorpo

ratio

n(ridging

)infurrow

TMM

Land

slashingand

plou

ghing

Maize

plantin

gNPK

application

andweeding

Mucun

aplantin

g

Weeding

and

urea

application

Maize

harvestin

gSlashing

andbiom

assincorpo

ratio

n(ridging

)infurrow

2003

or2005

cropping

season

T0Seed

yam

plantin

gmou

ndsc

apping

with

mulch

material

yam

staking

and

weeding

Weeding

Weeding

Yam

harvestin

g

TMSeed

yam

plantin

gmou

ndsc

apping

with

mulch

material

yam

staking

and

weeding

Weeding

Weeding

Yam

harvestin

g

TMA

Seed

yam

plantin

gmou

ndsc

apping

with

mulch

material

yam

staking

and

weeding

Weeding

Weeding

Yam

harvestin

g

TMM

Seed

yam

plantin

gmou

ndsc

apping

with

mulch

material

yam

staking

and

weeding

Weeding

Weeding

Yam

harvestin

g


rotatio

nTM

maize-yam

rotatio

nTM

AA

eschynom

eneh

istrix

maize

intercropp

ing-yam

rotatio

nTM

MM

ucun

aprurien

smaize

intercropp

ing-yam

rotatio

n

4 Scientifica














GomeT0 40 09 01 05 364 50 196TM 35 25 01 06 869 26 222TMA 90 12 01 04 1049 54 342TMM 98 16 01 06 1601 67 601






Scientifica 5






GomeT0 40 09 01 05 363 50 195TM 35 25 01 06 865 26 222TMA 93 12 01 04 1079 56 352TMM 96 16 01 06 1573 66 591



3 Results










6 Scientifica






T0 41c 39c

TM 35d 32d

TMA 92b 83b

TMM 97a 88a



4 Discussion





Scientifica 7














8 Scientifica




















Scientifica 9


(a)



(b)



(c)



10 Scientifica

(d)



(e)
















Scientifica 11


5 Conclusions


Competing Interests


Acknowledgments


References





















12 Scientifica
























Journal of




Agronomy





Microbiology




Volume 2014
























4 Scientifica














GomeT0 40 09 01 05 364 50 196TM 35 25 01 06 869 26 222TMA 90 12 01 04 1049 54 342TMM 98 16 01 06 1601 67 601






Scientifica 5






GomeT0 40 09 01 05 363 50 195TM 35 25 01 06 865 26 222TMA 93 12 01 04 1079 56 352TMM 96 16 01 06 1573 66 591



3 Results










6 Scientifica






T0 41c 39c

TM 35d 32d

TMA 92b 83b

TMM 97a 88a



4 Discussion





Scientifica 7














8 Scientifica




















Scientifica 9


(a)



(b)



(c)



10 Scientifica

(d)



(e)
















Scientifica 11


5 Conclusions


Competing Interests


Acknowledgments


References





















12 Scientifica
























Journal of




Agronomy





Microbiology




Volume 2014
























Scientifica 5






GomeT0 40 09 01 05 363 50 195TM 35 25 01 06 865 26 222TMA 93 12 01 04 1079 56 352TMM 96 16 01 06 1573 66 591



3 Results










6 Scientifica






T0 41c 39c

TM 35d 32d

TMA 92b 83b

TMM 97a 88a



4 Discussion





Scientifica 7














8 Scientifica




















Scientifica 9


(a)



(b)



(c)



10 Scientifica

(d)



(e)
















Scientifica 11


5 Conclusions


Competing Interests


Acknowledgments


References





















12 Scientifica
























Journal of




Agronomy





Microbiology




Volume 2014
























6 Scientifica






T0 41c 39c

TM 35d 32d

TMA 92b 83b

TMM 97a 88a



4 Discussion





Scientifica 7














8 Scientifica




















Scientifica 9


(a)



(b)



(c)



10 Scientifica

(d)



(e)
















Scientifica 11


5 Conclusions


Competing Interests


Acknowledgments


References





















12 Scientifica
























Journal of




Agronomy





Microbiology




Volume 2014
























Scientifica 7














8 Scientifica




















Scientifica 9


(a)



(b)



(c)



10 Scientifica

(d)



(e)
















Scientifica 11


5 Conclusions


Competing Interests


Acknowledgments


References





















12 Scientifica
























Journal of




Agronomy





Microbiology




Volume 2014
























8 Scientifica




















Scientifica 9


(a)



(b)



(c)



10 Scientifica

(d)



(e)
















Scientifica 11


5 Conclusions


Competing Interests


Acknowledgments


References





















12 Scientifica
























Journal of




Agronomy





Microbiology




Volume 2014
























Scientifica 9


(a)



(b)



(c)



10 Scientifica

(d)



(e)
















Scientifica 11


5 Conclusions


Competing Interests


Acknowledgments


References





















12 Scientifica
























Journal of




Agronomy





Microbiology




Volume 2014
























10 Scientifica

(d)



(e)
















Scientifica 11


5 Conclusions


Competing Interests


Acknowledgments


References





















12 Scientifica
























Journal of




Agronomy





Microbiology




Volume 2014
























Scientifica 11


5 Conclusions


Competing Interests


Acknowledgments


References





















12 Scientifica
























Journal of




Agronomy





Microbiology




Volume 2014
























12 Scientifica
























Journal of




Agronomy





Microbiology




Volume 2014


























Journal of




Agronomy





Microbiology




Volume 2014
























Research Article Dry Matter Production, Nutrient Cycled...

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