Research Article Tillage Effects on Selected Soil Physical...

Research ArticleTillage Effects on Selected Soil Physical Properties in aMaize-Bean Intercropping System in Mwala District Kenya

Anne Karuma1 Peter Mtakwa1 Nyambilila Amuri1

Charles K Gachene2 and Patrick Gicheru3

1 Department of Soil Science Sokoine University of Agriculture PO Box 3151 Morogoro Tanzania2Department of Land Resource Management and Agricultural Technology (LARMAT) University of NairobiPO Box 29053 Nairobi Kenya

3National Agricultural Research Laboratories (KARI) P O Box 14733 Nairobi Kenya

Correspondence should be addressed to Anne Karuma annekarumagmailcom

Received 26 May 2014 Accepted 5 August 2014 Published 3 November 2014

Academic Editor Jordan Manuel

Copyright copy 2014 Anne Karuma et al This is an open access article distributed under the Creative Commons Attribution Licensewhich permits unrestricted use distribution and reproduction in any medium provided the original work is properly cited

A field study was carried out to evaluate the effects of tillage practices on soil physical properties in Mwala district Eastern Kenyaduring the long rains (LR) and short rains (SR) of 201213The treatments were disc ploughing (DP) disc ploughing and harrowing(DPH) ox-ploughing (OX) subsoiling-ripping (SSR) hand hoeing with tied ridges (HTR) hand hoeing only (H) These wereinvestigated under three cropping systems of sole maize sole bean and maize-bean intercrop in a split-plot design with fourreplications Soil physical properties were monitored at different weeks after planting (WAP) throughout the growing seasonsA four-season average shows that soil moisture content was significantly (119875 lt 005) higher in OX gt SSR gt DPH gt H gt HTR gt DPwith values ranging from 131 to 141 Soil surface roughness and crust strength varied significantly (119875 lt 005) over time withinthe growing seasons between the tillage practices and across the different seasons with values ranging from 26 to 66 and 121 to131MPa respectively Tillage practices and cropping systems did not significantly affect bulk density porosity or 119870sat values It isapparent that long term tillage experiment (gt4 seasons) would be required to detect changes in soil physical properties as a resultof the soil management practices

1 Introduction

Smallholder agriculture in semiarid areas is hampered byaccelerated soil erosion induced soil moisture deficits soilfertility depletion and soil crusting and compaction [1]The soil crusting and compaction problem is attributedto inherent soil properties and poor tillage practices [2]The semiarid areas of Kenya are characterized by temporaland spatial variability of rainfall which is not suitable forsustainable rainfed agriculture [1 3] Thus resource-poorfarmers in these areas who entirely rely on rainfed agricultureare subject to various hydrological constraints The rainfalloccurrence is bimodal with two distinct rainy seasons theshort and long rains In Kenyarsquos semiarid areas the shortrains (October to December) are more reliable and areevenly distributed and more often support plant growth [4]However very high soilmoisture deficits experienced in these

areas usually result in significant decreases in crop yieldsunder rainfed conditions Deficit of soil moisture in theseareas is attributed to low infiltration rates caused by surfacesealing crusting low organicmatter content and subsequenthigh runoff rates [1 5 6] Soil moisture conservation undersuch conditions requires appropriate tillage practices thatnot only improve rainwater infiltration but also conserveadequate soil moisture for plant growth [7]

Soil tillage as a necessary practice in crop productioncan affect the soil physical properties that are importantfor plant growth [8 9] Improvements of root penetrationwater infiltration and soil moisture storage weed controland supply of nutrients from rapid decomposition of organicmatter are considered the most beneficial contributions oftillage to crop production [10ndash12]

Conventional tillage involves the mechanical soil manip-ulation of an entire field by ploughing (inverting the soil)

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2 International Scholarly Research Notices

followed by one or more harrowings The degree of soildisturbance depends on the type of implement used thenumber of passes type of soil and intended crop type[13] The most common conventional tillage practiced inKenya involves the use of hand hoes ox-drawn mould boardploughs tractor-drawn disc ploughs and harrows combinedwith straw collection and burning during land preparation[2 14] During the operation the soils are cut invertedand pulverized burying most of the residues underneath[14] Consequently in many areas especially semiarid areasconventional agriculture has led to a decline in crop yieldsand profitability when compared to those realized from areaswith higher rainfall [15]

Other sustainable techniques advocated in the semiaridareas for soil and water conservation have included tiedridging cover cropping mulching subsoiling and ripping[16 17] These techniques are referred to as conservationtillage and have the potential of soil moisture retention andmitigation of intraseasonal dry spells that often result inlow productivity and crop failure reduce soil evaporationand enable organic matter build-up which enhances waterholding capacity of the soil [18ndash20]

Conservation tillage practices are particularly importantfor increasing the productivity of water through reducingrunoff and evaporation and improving soil water storage[18] In Kenya promotion of animal-drawn conservationtillage tools such as rippers and subsoilers among smallholderfarmers has resulted in improvedwater productivity and cropyields [21 22] Although conservation tillage is highly advo-cated there is strong evidence that this kind of tillage maynot be good with soils prone to surface crusting and sealinga characteristic of most of the soils in the semiarid areas ofKenya [23ndash26] Therefore the local biophysical conditions inthe smallholder farming systems in these semiarid areas needto be considered and deliberate adaptation efforts made

The success of any tillage practices is directly related tothe improvement of the soil physical properties which in turnmay affect the growth and yield of crops due to the differentsoil conditions created In a review on the effect of soil phys-ical properties on soil moisture Strudley et al [27] showedthat bulk density porosity soil surface sealing and crustingsurface roughness hydraulic conductivity and infiltrationrates were highly influenced by different tillageTherefore thechoice of any tillage system is too critical for maintenanceof the soil physical properties necessary for crop growth[28] However the resulting effect of tillage on selectedphysical properties depends on the site-specific biophysicalenvironment such as seasonal variability in rainfall inherentsoil fertility status or the prevailing climatic conditions [29]Few studies have measured these soil physical propertiesespecially in semiarid Eastern Kenya hence the essence forthe study reported herein

Recent efforts have focused on minimum tillage prac-tices as a soil and water conservation measure [30 31]Nonetheless maize-legume cropping systems are popular inimproving land use efficiency and economic returns In orderto exploit these practices there is a need to understand theinfluence of tillage and cropping systems on selected soilphysical properties in dryland cropping systems for sustained

Table 1 Baseline chemical and physical properties of the experi-mental site (0ndash30 cm)

Soil property ValuespH (H2O) 650pH (001M CaCl2) 561C 110N 009K cmolkg 235Na cmolkg 046Ca cmolkg 231Mg cmolkg 039CEC cmolkg 670P (mgkg) 1350Sand () 2200Silt () 3900Clay () 3900Textural class Clay loamBulk density (gcm3) 127Saturated hydraulic conductivity (119870sat) (cmh) 027Saturation (cmcm3) 0664Field capacity (cmcm3) 0508Wilting point (cmcm3) 0480Plant available water (cmcm3) 0028

productivityThe objective of this study was to investigate theeffect of selected tillage practices and cropping systems onselected soil physical properties in semiarid Mwala districtEastern Kenya Specifically their effects on soil moisturesoil surface roughness crust strength saturated hydraulicconductivity bulk density and porosity

2 Materials and Methods

21 Study Site Description The study was conducted inMbiuni location Mwala district Machakos County EasternKenya (1∘151015840S 37∘251015840E) The area is characterized by lowerratic and poorly distributed bimodal rainfall that makescrop production difficult under rainfed conditions The longrains commence in mid-March and end in May while shortrains start in mid-October and end in late November Themean annual rainfall for Mwala district is 5967mm [32]Maize and beans dominate household consumption Pulsesare grown in the district and the predominant ones arebeans pigeon peas cowpeas green grams and chickpeasSoil chemical and physical properties at the site are given inTable 1 The study site was previously under beans and theslope was lt2

22 Experimental Design and Layout The trials were estab-lished in 2012 and ran for four seasons during the long (LR)(MarchndashMay) and short rains (SR) (OctoberndashDecember)(ie LR 2012 SR 2012 LR 2013 and SR 2013) The treatmentsconsisted of six tillage practices disc ploughing (DP) discploughing and harrowing (DPH) ox-ploughing (OX) handhoeing with tied ridges (HTR) hand hoeing only (H) and

International Scholarly Research Notices 3

subsoiling-ripping (SSR) The cropping systems treatmentswere sole maize sole bean and maize-bean intercrop Thetreatment factors were arranged in a split-plot design withtillage practices as the main plots and the cropping systemas the subplots and replicated four times in plot sizes of25m2 Time in weeks after planting (WAP) and season wereconsidered as experimental factors to test the changes withina growing season and across the different cropping seasons

23 Soil Properties Measurements Soil moisture was mon-itored from crop emergence to harvesting at depths of 0ndash20 cm and 20ndash40 cm using the gravimetric method [33]Monitoring of soil moisture was done at the 0ndash40 cm depthdue to the concentration of active roots at this level and lessbelow this depth range Soil surface roughness was measuredimmediately after the tillage operations and before weedingwas done Readings were taken from three randomly selectedpositions in each tillage plot A microrelief meter similar tothat described by Kuipers [34] was used to measure surfaceroughness

Crust strength (penetration resistance) was measured atthe soil surface (0ndash10 cm depth) using a hand-held pen-etrometer (Eijkelkamp equipment type 1B) in three seasons(SR 2012 LR 2013 and SR 2013) Ten soil crust strengthmeasurements were taken at randomly selected positions ineach plot The penetrometer springs and cone sizes wereadjusted depending on the soil strength Crust strength wascalculated as

CR = 119868 times ( CsAC) (1)

where CR is the cone resistance (N cmminus2) 119868 is the impressionon the scale (cm) Cs is the spring constant (N cmminus1) and ACis the area of the cone (cm2)

Saturated hydraulic conductivity (119870sat) determinationswere done in the laboratory using the constant head methodas described by Klute andDirksen [35] Undisturbed soil corerings (5 cm depth volume 9813 cm3) collected from the fieldwere carefully trimmed to the size of the core ring A piece ofmuslin cloth held with a rubber band was used on one sideof the core ring to protect the soil from spilling but to allowwater to pass throughThe samples were then saturated for 24hours before water percolation tests were done The volumeof water that passed through the soil sample was measuredand recorded until a constant average was achieved The119870satwas then calculated as

119870sat = 119876 times119871

(119860 times 119879 times 119867) (2)

where 119876 is the discharge or percolate through the soil (cm3or mL) 119871 is the length of the soil core (cm) 119860 is the cross-sectional area of the soil core (cm3) 119879 is the time taken(hours) and119867 is the hydraulic head difference (cm)

The bulk density was determined using undisturbed coresamples from each plot Soil core samples were carefullytrimmed at both sides to the size of the core ring The soilcorewas then oven-dried at 105∘C to a constantmass and thenweighed Bulk density was then calculated as the mass of the

dry soil divided by the core ring volume Total porosity wasthen calculated from the bulk density as

Total porosity = (1 minus120588119887

120588119904

) (3)

where 120588119887is the bulk density and 120588

119904is the average particle den-

sity (265Mgm3) The 119870sat bulk density and total porositywere determined at one or two intervals in a growing season(the beginning of the season (3 WAP) and at harvest)

24 CropManagement Adrylandmaize variety (DH02) andbeans (rose coco GLP 2) were used as the test crops Thesecrops were planted in rows in 25m2 plots The maize wasplanted at a spacing of 90 times 30 cm in pure stands while thebean plants were planted at a spacing of 45times 15 cm In the tiedridging plots maize and beans were planted in the same rowbut in alternating hills Thinning was done to a single plantper hill for maize and two plants for the legume four weeksafter germination

In each cropping system the nitrogen was applied at60 kgNhaminus1 (DAP 18 46 0) at planting to the maize andadditional 60 kgNhaminus1 (CAN 26 0 0) was top-dressedwhen maize was knee-high (4 WAP) The beans were inocu-lated with Bio-Fixcopy biofertilizer before sowing All plots werehand-weeded using a hand hoe as practiced by the farmersduring the cropping periods No crop rotation was doneduring the study

25 Statistical Analysis In analysis of the soil propertiesanalysis of variance (ANOVA) with repeated measures wasused using Genstat 14th Edition statistical software Meanseparation was done using LSD at 5 level of probabilitywhere the ANOVA F-values were significant

3 Results and Discussion

31 Soil Moisture Content as Affected by Tillage Practices andCropping Systems between Season and Depth Tillage prac-tices resulted in significant differences in moisture contentin LR 2012 (119875 = 0019) LR 2013 (119875 = 0003) and SR2013 (119875 = 0001) but not in SR 2012 (119875 = 0158) (Table 2)However in SR 2012 higher moisture levels were observedin OX (153) and SSR (144) The OX and SSR plotsmaintained high moisture levels in the SR 2012 and LR 2013Subsoiling-ripping (SSR) and ox-ploughing (OX) enhancewater penetration into deeper soil layers and allow deeperrooting of crops that benefit from stored water and nutrientsas they exploit larger soil volumes Steiner and Rockstrom[36] made similar observations In LR 2012 the HTR plotshad high moisture levels (156) due to the microbasinformation that traps rainwater and allowed more time forinfiltration and storage In contrast to LR 2012 HTR had thelowest moisture (842) in the LR 2013 season

Similar findings are supported by Guzha [37] who foundthat the higher moisture was stored in ridges and thiswas associated with higher roughness resulting from ridgeconfiguration Tied ridges create rectangular basins between


Table 2 Soil moisture content () as affected by tillage cropping systems and depth (119899 = 4 seasons)

Soil moisture ()LR 2012 SR 2012 LR 2013 SR 2013 Mean

TillageHand hoeing only (H) 1457 1374 963 1539 1333Hand hoeing with tied ridges (HTR) 1561 1380 842 1526 1327Disc ploughing (DP) 1368 1394 882 1589 1308Disc ploughing + harrowing (DPH) 1509 1366 866 1618 1340Ox-ploughing (OX) 1455 1533 998 1655 1410Subsoiling-ripping (SSR) mdash 1435 996 1598 1343Mean 1470 1414 925 1587 1344

Cropping systemSole bean 1474 1419 948 1594 1359Sole maize 1471 1421 905 1596 1348Intercrop 1465 1402 920 1572 1340

Depth0ndash20 cm 1385 1309 804 1515 125320ndash40 cm 1555 1518 1044 1659 1444

Significance levelsTime (weeks after planting) lt0001 lt0001 lt0001 lt0001 lt0001Tillage 0019 0158 0003 lt0001 lt0001Cropping systems 0891 0684 0547 0895 0899Depth lt0001 lt0001 lt0001 0003 lt0001

(mdash) not measured in that season

ridges which increase surface retention capacity anddecreaserunoff thus improving soil moisture content and ultimatelycrop growth and yields Motsi et al [38] in Zimbabwe foundthat tied ridges retained significantly higher moisture thanconventional tillage (ploughing) especially during the drymonths While Gicheru et al [39] found that tied ridgingconserved the lowest amount of moisture and attributed thisto no runoff to impound and high evaporation losses dueto increased soil surface area exposure in the semiarid areasof Laikipia district Kenya Gursoy et al [40] in semiaridTurkey found that ridge tillage accelerated drying of theseed zone thus low moisture contents were observed Somewater logging was observed in the LR 2012 season only andcould explain the high moisture by HTR (1561) noted andhence the lowest moisture contents in the succeeding seasons(Table 2) Therefore the effectiveness of tied ridges dependson the rainfall received and climatic conditions within aseason

The soil moisture decreased over time (WAP) during thefour growing seasons (119875 lt 005) Across the profile thesoil moisture was higher in the 20ndash40 cm than in the 0ndash20 cm depth and varied among the different tillage practicesin all seasons (119875 lt 005) The changes in profile moisturecontent could be attributed to a combination of rainfall soilevaporation and transpiration or crop water uptake [25 4142] When the soil moisture content for each tillage methodwas averaged for the four seasons a significant seasonaldifference was found (119875 lt 005) (Table 2) Soil moisturecontent by tillage was higher in OX gt SSR gt DPH gt Hgt HTR gt DP (119875 lt 005) Fabrizzi et al [43] reported

an increase in soil moisture storage under conservationtillage due to decreases in evaporation increases in the soilinfiltration and the enhanced soil protection from rainfallimpact The average low soil moisture contents observedcould be attributed to reduced water infiltration This is dueto the breaking of the large pores while the small pores areclogged by the dislocation of soil particles which depend ontillage methods [44] Soil moisture is the single most limitingfactor to crop yields and thus tillage techniques that conservemoisture are important for increasing crop yields and limitingthe devastating consequences of drought in semiarid areas[45]

There were no significant effects on soil moisture contentdue to the cropping system for all the seasons (119875 = 0899)(Table 2) However in SR 2012 and LR 2013 there weresignificant (119875 lt 005) time times cropping systems interactionsFrom the results there are inconsistencies observed by thecropping systems for each season on soil moisture contentsthat can be attributed to the varying crop requirementsand climate conditions [46] Soil water extraction by cropsis determined not only by soil water content evaporativedemand and soil physical properties but also by physiologicalstatus of the crop [47] and could explain the nonsignificanteffects observed

32 Soil Surface Roughness Soil surface roughness variedsignificantly (119875 lt 005) over time in the growing seasonsbetween the tillage practices and across the different seasons(Table 3) A four-season summary shows a trend of HTRgt SSR gt DP gt OX gt DPH gt H Soil surface roughness


soon after tillage was significantly higher among the tillagepractices (119875 lt 005) and decreased progressively in eachseason (Table 3) The HTR SSR and DP had consistentlyhigher values in all the four seasons with overall averagevalues ranging from 27 to 66

The high surface roughness in HTR can be attributedto the raised ridges and basins created during tied ridgingThe SSR plots had also higher surface roughness probablybecause of the furrows created during ripping Ripping isusually done to open a narrow slit or furrow in the soil forsowing seeds while leaving unploughed sections between theplanting rows [16] The high values obtained in the DP plotscould be attributed to the greater plough depth resultingin higher soil surface roughness which enhances greaterinfiltration primarily by surface retention of water in thesmall holes and depression Soil surface roughness changesconsiderably with rainfall wind and cultivation events asindicated by Guzha [37] Mupangwa et al [48] and Morenoet al [49] Lampurlanes and Cantero-Martınez [6] reviewedthat surface roughness produced by tillage increases surfaceponding which allows rainwater to infiltrate into the soilthus preventing runoff and increasing moisture retention inthe soil profile This explains why HTR had higher moisturelevels in the LR2012 seasondue to thewater logging observedTherefore management practices aimed at adjusting thesoil surface characteristics can promote soil processes thatencourage soil moisture storage within the root zone [49 50]

33 Crust Strength Crust strength was affected significantly(119875 lt 005) by the time of measurement tillage and thegrowing season There were also significant interactions oftime times season tillage times season and time times tillage times season(119875 lt 005) observed The cropping systems did not influencethe crust strength in the three seasons (119875 = 0379)

Increase in crust strength as a season progressed wasnoted (Table 4) and could be attributed to natural formationof crust under raindrop impact since there was minimalhuman interference only duringweeding and data collectionMost soils in sub-Saharan Africa suffer from poor physicaland chemical properties which combined with intensiverainfall events make them particularly sensitive to crustformation [24 37]

The average trend of crust strength observed during theSR 2012 seasonwas in the order of SSRgtOXgtDPHgtHgtDPgt HTR with values ranging from 103 to 118MPa (Table 4)The crust formed on the ridges was weaker than other tillagepractices as the season progressed A probable cause of thiswas the inversion and mixing of top soil when constructingthe tied ridges and this could have affected the structure ofthe top soil However at the base of the ridge basins the cruststrength was higher in all the seasons because of the excessivedrying of the soil in the basin owing to direct insolation

The crust strength trend observed during the LR 2013season was in the decreasing order of SSR gtOX gtDP gtHTRgtHgtDPHwith average values ranging from 142 to 150MPa(Table 4) Lower crust strength in H and DPH could be dueto the loosening effect of the tillage used

During the SR 2013 season a trend of SSR gt OX gt Hgt DP gt DPH gt HTR was observed with values rangingfrom 114 to 122MPa A three-season average trend showsa decreasing trend of SSR gt OX gt H gt DP gt DPH gt HTRwith values ranging from 121 to 130MPa These results arein line with those reported by Khurshid et al [51] where soilunder conventional tillage (use of rigger in ridge tillage anduse of a cultivator in deep tillage plots) had lower penetrationresistance than minimum tillage (dibbling) treatments inthe semiarid Faisalabad PakistanTherefore intensive tillageas observed in DP DPH and HTR causes a breakdownof soil surface sealing resulting in the weak crust strengthobserved (Table 4) The high crust strength observed in theSSR plots could be attributed to nonploughing of the soilsbetween the planting rows [16] This premise is supportedby Miriti et al [52] who observed higher crust in subsoiling-ripping (047MPa) followed by tied ridging (040MPa) andox-ploughing (015MPa) respectively working in Makuenidistrict Eastern Kenya The cropping systems did not sig-nificantly affect (119875 = 0379) the crust strength but anoverall average trend of intercrop (1263MPa) gt sole maize(1258MPa) gt sole bean (1251MPa) was noted

Penetration resistance decreased with increases in soilmoisture content and vice versa [53] Penetrometer readingsgreater than 2MPa are generally reported to produce a signif-icant root growth reduction [54] which was not observed inthis study According to Lampurlanes and Cantero-Martınez[11] penetration resistance measured with a penetrometeris usually two to eight times greater than that actuallyundergone by the root tip owing to the different way inwhichroots and probes penetrate the soil However roots can growat a speed greater than the penetrometer reading becausethey can elongate through the biopores and interaggregatespaces [11] Thus the crust strength obtained in this studyin all treatments and seasons is not expected to limit rootpenetration and plant growth

34 Bulk Density Porosity and Saturated Hydraulic Conduc-tivity (119870

119904119886119905) The bulk densities of the soils ranged from

120Mgmminus3 to 142Mgmminus3 across the seasons which arewithin the acceptable range for a clay loam (Table 1) [55]Thecurrent study shows variation across the seasons (119875 lt 005)(Table 5) Though not significant (119875 = 0312) the averagebulk density trend observed was DPH gt SSR gt H gt OX gtHTR gt DP The cropping systems did not influence the bulkdensities in the four seasons (119875 = 0502)

In the SR 2012 season the bulk density increased(134Mgmminus3) at the end of the season from 127Mgmminus3 atthe beginning of that season while in the SR 2013 higherbulk density (155Mgmminus3) was noted at the beginning of SR2013 and was lower at the end of that season (135Mgmminus3)According toHusnjak et al [56] tillage at the beginning of thegrowing season temporarily decreases soil bulk density butsubsequent trips in the field for agronomic practices rainfallevents and other disturbances activities can recompact thesoil Lower bulk density at the end of the growing seasoncould be attributed to the short term loosening effect of thetillage method used


Table3Eff

ecto

ftillageo

nsoilsurfa

ceroug

hness(119899=4season

s)

Tillage

Long

rains(LR

2012)

Shortrains

(SR2012)

Long

rains(LR

2013)

Shortrains

(SR2013)

Atplou

ghing

Before

plantin

g3WAP

Atplou

ghing

Before

plantin

g3WAP

Atplou

ghing

Before

plantin

g3WAP

Atplou

ghing

Before

plantin

g3WAP

H368

ab318

b271b

307

a230

a162

a345

a255

a132

a390

a313

ab268

bc

HTR

750

d725

d652

d678

d64

9d

586

c716

d626

d556

c724

c639

d560

d

DP

537

c485

c40

7c

330

ab266

ab225

a368

ab278

ab195

a571b

498

c376

c

DPH

298

a179a

135

a369

b337

b212

a40

7b

317

b182

a412

a287

a240

ab

OX

481b

c387

b321b

c46

7c

320

b170a

505

c415

c140

a511b

421b

c147

a

SSR

mdashmdash

mdash508

c472

c366

b546

c456

c336

b552

b451c

343

bc

Mean

487

419

357

4432

3788

287

481

391

257

527

435

322

LSD(5)

1209

769

1075

5212

685

812

52

52

81

905

1255

1133

CV

9465

7748

63

7844

54

87

44

31

57

TillageH

handho

eing

only

HTR

handho

eing

with

tiedrid

gesDP

disc

plou

ghingDPH

disc

plou

ghing+harrow

ingOX

ox-ploug

hing

SSR

sub

soiling

-ripping

and

(mdash)no

tmeasuredin

thatseason

Differentletterswith

inthec

olum

nsindicatesig

nificantd

ifference

at5

prob

abilitylevel


Table4Soilcruststre

ngth

asinflu

encedby

timeo

fmeasurementtillage

practicesand

thec

ropp

ingsyste

ms(119899=3season

s)

Soilcruststre

ngth

(MPa)

Shortrains

2012

Long

rains2

013

Shortrains

2013

3WAP

7WAP

10WAP

15WAP

4WAP

6WAP

10WAP

16WAP

4WAP

8WAP

12WAP

17WAP

Tillage

H10

34a

1001

1272

1269

1187

a15

5315

7414

691187

a13

5014

680747a

b

HTR

0905b

1007

1088

1124

1133

a14

9416

8015

261133

b12

8214

620672c

DP

1111

a10

5512

081193

1188

a14

7517

0814

721188

a13

4114

150728b

c

DPH

1094

a10

2312

5512

171136

a14

6016

7114

511136

b13

0114

170769a

b

OX

1136

a10

2512

5612

341175

a15

6116

7314

781175

ab13

5514

530807a

SSR

1111

a10

6712

3012

9612

09a

1568

1705

1519

1209

a13

5714

800815a

LSD5

0111

0106

0162

0088

0047

0105

0108

0069

0047

0067

0053

0072

Crop

ping

syste

mSolebean

1026

1032

1221

1241

1177

1529

1617

b14

791177

1314

1441

0756

Solemaize

1086

1006

1208

1204

1161

1530

1713

a14

821161

1338

1462

0749

Intercrop

1085

1051

1225

1222

1176

1496

1675

a14

961176

1340

1445

0765

LSD5

0072

006

40052

0036

0051

004

60047

0036

0051

0041

0029

004

8Sign

ificancelevels

Tillage

0005

0741

0218

0012

0018

0165

0160

0193

0018

0129

0085

0007

Crop

ping

syste

m0171

0369

0794

0131

0773

0245

lt0001

0571

0773

0374

0272

0798

Tillagetimescrop

ping

syste

m046

60493

040

60043

0672

0151

0789

0576

0672

0266

0278

0935

CV

32

69

52

42

1650

1728

1615

09

102

TillageH

handho

eing

only

HTR

handho

eing

with

tiedrid

gesDP

disc

plou

ghingDPH

disc

plou

ghing+harrow

ingOX

ox-ploug

hing

and

SSR

subsoilin

g-rip

ping


inthec

olum

nsindicatesig

nificantd

ifference

at5

prob

abilitylevel


Table 5 Effect of tillage practices and cropping systems on soil bulk density porosity and saturated hydraulic conductivity (119870sat)

Bulk density (Mgm3) Porosity () 119870sat (cmh)Timeseason

LR 2012b 143 4619 065SR 2012a 127 5195 179SR 2012b 134 4932 101LR 2013a 142 4641 027SR 2013a 155 4139 036SR 2013b 135 4915 054

TillageHand hoeing only (H) 140 4726 069Hand hoeing with tied ridges (HTR) 139 4775 098Disc ploughing (DP) 137 4846 071Disc ploughing + harrowing (DPH) 141 4671 077Ox-ploughing (OX) 139 4742 082Subsoiling-ripping (SSR) 141 4694 066Mean 140 4742 077

Cropping systemSole bean 138 4777 083Sole maize 039 4745 074Intercrop 140 4709 076

Significance levelsTime lt0001 lt0001 lt0001Tillage 0312 0312 0408Cropping system 0502 0502 0744CV 915 1014 2552

aBeginning of season bat harvest

The high densities in DPH and SSR could be attributedto the second passes of soil manipulation (harrowing andripping) to the initial tillage method of disc ploughing andsubsoiling in the respective plots Agbede [57] found highbulk densities in the ploughing plus harrowing plots andattributed that to tractor wheel traffic and implement passesand lower macroporosity The plough layer gets compactedas the tillage implement keeps passing the same depth seasonafter season thus increasing the bulk density Eventuallysuch structural degradation can lead to a formation of asurface seal that further reduces infiltration and hinders seedgermination [58] The increase in bulk density in the SSRplots especially at the beginning of a season could also beattributed to the compacted unploughed sections during theland preparation

Nonsignificance of tillage effect on bulk density over timehas also been observed in other studies by Lampurlanes andCantero-Martınez [11] Anken et al [59] Osunbitan et al[60] and Jabro et al [61] due to different tillage practicesIn contrast Khan et al [62 63] reported higher bulk densitywith minimum tillage and lower bulk density with deeptillage McVay et al [45] reported that bulk density wasgreater in no-till than conventional tillage in a long termstudy at Manhattan and Ashland Bottoms sites in KansasUSA The bulk density is dependent on soil texture and thedensities of soil minerals as well as their packing arrangement[58] Generally bulk density is not affected much by tillage

practices [60] Gomez et al [64] realized that it took fiveyears before changes in some of the soil physical properties(structure and aggregate stability which are indicators of bulkdensity) could be detected as a result of the soil managementpractices Full effect of tillage is observed after four to fiveyears and this could not be obtained in our short term study

Total porosity values of the soils varied across the seasons(119875 lt 005) and ranged from 42 to 52 in all the seasons(Table 5) Though not significant the tillage trend (119875 =0312) showed that conventional tillage plots had numericallygreater porosity due to the lower bulk density achieved bythe tillage method used Soils with lt40 total pore space areliable to restrict root growth due to excessive strength [58]However in this study soil strengthmeasured is not expectedto restrict root growth According to Gardner et al [10]conventional tillage improved soil porosity by increasing themacroporosity Since porosity is calculated from the relationbetween bulk density and particle density of soil it is verymuch influenced by the soil bulk density as the particledensity is not greatly altered by agricultural manipulations[65] For any given soil the higher the bulk densities themore compacted the soil and the less the pore space asalso observed in this study This also affects the soil watertransmission properties [66 67]

Cropping system did not show a significant influenceon the porosity (119875 = 0502) but sole bean and maizeshowed higher porosity values than the intercrop (Table 5)


This contrasts with results by Cheng and Coleman [68]and Fan et al [69] who found an increase in porosity afterintercropping and attributed that to increased root biomassand the stimulatory effects of the living roots on microbialactivities that enhance soil organic matter decompositionThe distribution of roots in the profile thus determines theplants ability to absorb soil moisture

The 119870sat values varied across the season (119875 lt 005) andwere very slow (lt08 cmh) in LR 2012 slow (08ndash20 cmh)in SR 2012 and very slow (lt08 cmh) in LR 2013 and SR2013 [55] (Table 5) Tillage did not significantly affect 119870satvalues (119875 = 0408) but an average trend of 119870sat amongtillage treatments was HTR gt OX gt DPH gt DP gt H gt SSRwith values ranging from 066 cmh to 098 cmhThere wereno significant interactions observed among the croppingsystems (119875 = 0744) The low 119870sat values in SSR plots havebeen reported elsewhere by Miriti et al [52] in Makuenidistrict Kenya who attributed it to the restricted lateralmovement of water due to the low porosity in the unploughedsections

Non-significant results on saturated hydraulic conduc-tivity (119870sat) over time have also been observed by Changand Lindwall [70] after 20 years of tillage in a clay loamsoil in Alberta Furthermore inversion tillage (ploughing)makes the aggregates unstable during wetting which couldcause lower 119870sat Pikul Jr and Aase [71] demonstrated thatcontinuous tillage for 11 years in a dryland site in EasternMontana USA resulted in low 119870sat due to a compacted 10ndash15 cm layer that impeded water movement A soil profiledescription done at this study site showed a high bulkdensity of 154Mgm3 in the Ap horizon (0ndash10 cm depth) thatimpeded water infiltration as indicated by the low 119870sat valueof 037 cmh obtained

Green et al [72] also reported that the effects of tillage onthe soil hydraulic properties under different tillage treatmentsare not always consistent across locations soils and experi-ment designsThe overall low119870sat values observed imply lowinfiltration rates and thus low rainwater intake by the soil[58] The low 119870sat values could also be influenced by the soilparticle size which is reflected in the texture of the soil [57]This soil has a clay loam texture (39 clay) which has smallergrains and thus lower hydraulic conductivity [67] These lowvalues observed in this study also indicate the presence of ahardpan and thus deep subsoiling is required to improve thesoil water uptake [55 71]

4 Conclusion

Soil moisture conservation is important during land prepara-tion and crop growth due to climate change which affects theamount of rainfall and the rainfall seasons The soil moisturetrends by tillage and cropping systems were inconsistent ineach cropping season However on average the OX SSRand the DPH conserved the highest moisture Nonsignificantresults by tillage and cropping systems were also observedon bulk density porosity and 119870sat values The DP HTR andOX plots had numerically greater porosity (gt45) due tothe lower bulk density achieved by the tillage method used

Based on the soil physical properties measured in this studythere was no significant advantage of a tillage practice overthe other as the soil physical properties developed slowlyafter initiation of tillage practices This suggests that longterm tillage experiments (gt4 seasons) under similar environ-mental and soil conditions are required to detect changes insoil physical properties as a result of the soil managementpracticesThe long term studies will thus provide site-specificrecommendations of the appropriate tillage practices foradoption in these semiarid areas

Conflict of Interests

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

Acknowledgments

This study was supported by the Regional UniversitiesForum for Capacity Building in Agriculture (RUFORUM)and International Development Research Centre (IDRC)through Sokoine University of Agriculture (SUA) TanzaniaThe authors thank Mrs Josephine Mutuku for providing herfarm for conducting this study and Stanley Kisamuli for thetechnical support in the field

References

[1] P N M Njeru J Mugwe I Maina et al ldquoIntegrating sci-entific and farmersrsquo perceptions towards evaluation of rainfedagricultural technologies for sorghum and cowpea productivityin Central Kenyardquo Journal of Soil Science and EnvironmentalManagement vol 4 no 7 pp 123ndash131 2013

[2] E K Biamah ldquoCoping with drought options for soil andwater management in semi-arid Kenyardquo Tropical ResourceManagement Papers 58 Wageningen University and ResearchCentre Wageningen The Netherlands 2005

[3] J O Wamari V I Sijali L H Kheng J M Miriti and A OEsilaba ldquoUse of Aquacrop model to predict maize yields undervarying rainfall and temperature in a semi-arid environment inKenyardquo Journal of Meteorology and Related Sciences vol 6 pp23ndash32 2012

[4] R Jaetzold H Schmdt B Hornetz and C A Shisanya FarmManagement Handbook of Kenya Natural Conditions and FarmInformation vol 11 Ministry of AgricultureGIZ NairobiKenya 2nd edition 2006

[5] J Rockstrom J Barron and P FoxWater Productivity in Rain-fed Agriculture Challenges and Opportunities for SmallholderFarmers inDrought ProneTropical Agroecosystem CABI IWMIWallingford UK 2003

[6] J Lampurlanes and C Cantero-Martınez ldquoHydraulic conduc-tivity residue cover and soil surface roughness under differenttillage systems in semiarid conditionsrdquo Soil andTillage Researchvol 85 no 1-2 pp 13ndash26 2006

[7] W M Cornelis T Araya J Wildermeersch et al ldquoBuildingresilience against drought the soil-water perspectiverdquo inDeser-tification and Land degradation Processes andMitigation M DeBoever M Khlosi N Delbecque et al Eds pp 1ndash15 UNESCOChair of Eremology Ghent University Brussels Belgium 2013


[8] M Rashidi and F Keshavarzpour ldquoEffect of different tillagemethods on soil physical properties and crop yield of melon(Cucumis melo)rdquo ARPN Journal of Agricultural and BiologicalScience vol 3 no 2 pp 41ndash46 2008

[9] S Aikins M H J J Afuakwa O Owusu and O Owusu-Akuoko ldquoEffect of four different tillage practices on maizeperformance under rainfed conditionsrdquoAgriculture and BiologyJournal of North America vol 3 no 1 pp 25ndash30 2012

[10] C Gardner K B Laryea and P W Unger Soil Physical Con-straints to Plant Growth and Crop Production AGLMISC2499 FAO Land and Water Development Division FAO RomeItaly 1999

[11] J Lampurlanes and C Cantero-Martınez ldquoSoil bulk densityand penetration resistance under different tillage and cropmanagement systems and their relationship with barley rootgrowthrdquo Agronomy Journal vol 95 no 3 pp 526ndash536 2003

[12] T A Spedding C Hamel G R Mehuys and C AMadramootoo ldquoSoil microbial dynamics in maize-growing soilunder different tillage and residue management systemsrdquo SoilBiology and Biochemistry vol 36 no 3 pp 499ndash512 2004

[13] Food and Agriculture Organization Manual on Integrated SoilManagement and Conservation Practices FAO Land and WaterBulletinNo 8 Food andAgricultureOrganization of theUnitedNations Rome Italy 2000

[14] C K K Gachene and G Kimaru Eds Soil Fertility andLand Productivity A Guide for Extension Workers in theEastern Africa Region RELMA Technical Handout Series 30Regional Land Management Unit (RELMA) Swedish Inter-national Development Cooperation Agency (SIDA) NairobiKenya 2003

[15] F SMurungu ldquoConservation agriculture for smallholder farm-ers in the Eastern Cape Province of South Africa recent devel-opments and future prospectsrdquo African Journal of AgriculturalResearch vol 7 no 38 pp 5278ndash5284 2012

[16] WOCATWhere the Land is GreenermdashCase Studies and Analysisof Soil and Water Conservation Initiatives Worldwide edited byHanspeter Liniger and William Critchley CTA FAO UNEPand CDE University of Bern Bern Switzerland 2007

[17] H P Liniger R Mekdaschi Studer C Hauert and M Gurt-ner Sustainable Land Management in PracticemdashGuidelinesand Best Practices for Sub-Saharan Africa TerrAfrica WorldOverview of Conservation Approaches and Technologies(WOCAT) and Food and Agriculture Organization of theUnited Nations (FAO)

[18] R Lal ldquoEnhancing crop yields in the developing countriesthrough restoration of the soil organic carbon pool in agricul-tural landsrdquo Land Degradation and Development vol 17 no 2pp 197ndash209 2006

[19] G Nyamadzawo R Chikowo P Nyamugafata J Nyamangaraand K E Giller ldquoSoil organic carbon dynamics of improvedfallow-maize rotation systems under conventional and no-tillage in Central Zimbabwerdquo Nutrient Cycling in Agroecosys-tems vol 81 no 1 pp 85ndash93 2008

[20] A M Manyatsi N Mhazo M Mkhatshwa and M T Masari-rambi ldquoThe effect of different in-situ water conservation tillagemethods on growth and development of Taro (Colocasia escu-lenta L)rdquo Asian Journal of Agricultural Sciences vol 3 no 1 pp11ndash18 2011

[21] P Kaumbutho and J Kienzle Conservation Agriculture aspracticed in Kenya Two case studies African ConservationTillage Centre de Cooperation Internationale de Recherche

Agronomique pour le Developpement Food and AgricultureOrganisation of the United Nations

[22] P Kathuli P K Itabari S N Nguluu and E M GichangildquoFarmers perception on subsoilingripping technology for rain-water harvesting in mixed dryland farming areas in EasternKenyardquo in Proceedings of the 12th KARI Biennial ScientificConference pp 1235ndash1240 Nairobi Kenya 2010

[23] P W Unger B A Stewart J F Parr and R P Singh ldquoCropresidue management and tillage methods for conserving soiland water in semi-arid regionsrdquo Soil and Tillage Research vol20 no 2-4 pp 219ndash240 1991

[24] A N Gitau L O Gumbe and E K Biamah ldquoInfluence of soilwater on stress-strain behaviour of a compacting soil in semi-arid Kenyardquo Soil and Tillage Research vol 89 no 2 pp 144ndash1542006

[25] M Mujdeci B Kara and A A IsiIdar ldquoThe effects of differentsoil tillage methods on soil water dynamicrdquo Scientific Researchand Essays vol 5 no 21 pp 3345ndash3350 2010

[26] K E Giller M Corbeels J Nyamangara et al ldquoA researchagenda to explore the role of conservation agriculture inAfricansmallholder farming systemsrdquo Field Crops Research vol 124 no3 pp 468ndash472 2011

[27] M W Strudley T R Green and J C Ascough II ldquoTillageeffects on soil hydraulic properties in space and time state ofthe sciencerdquo Soil and Tillage Research vol 99 no 1 pp 4ndash482008

[28] R Lal ldquoLong-term tillage and maize monoculture effects on atropical alfisol in westernNigeria I Crop yield and soil physicalpropertiesrdquo Soil and Tillage Research vol 42 no 3 pp 145ndash1601997

[29] Y Abbaspour-Gilandeh V R Sharabiani and A KhalilianldquoEffects of tillage methods on soil fragmentation in loamy-claysoilsrdquo American Journal of Agricultural and Biological Sciencevol 4 no 2 pp 131ndash136 2009

[30] P Gicheru C Gachene J Mbuvi and E Mare ldquoEffects of soilmanagement practices and tillage systems on surface soil waterconservation and crust formation on a sandy loam in semi-aridKenyardquo Soil and Tillage Research vol 75 no 2 pp 173ndash1842004

[31] S N Ngigi J Rockstrom and H H G Savenije ldquoAssessment ofrainwater retention in agricultural land and crop yield increasedue to conservation tillage in Ewaso Ngrsquoiro river basin KenyardquoPhysics andChemistry of the Earth vol 31 no 15-16 pp 910ndash9182006

[32] R K Ngugi S M Mureithi and P N Kamande ldquoClimateforecast information the status needs and expectations amongsmallholder agro-pastoralists in Machakos District KenyardquoInternational Journal of Current Research vol 3 no 11 pp 6ndash12 2011

[33] J R Okalebo K W Gathua and P L Woomer LaboratoryMethods of Soil and Plant Analysis A Working Manual TSBF-CIAT and Sacred Africa Nairobi Kenya 2nd edition 2002

[34] H Kuipers ldquoA relief meter for soil cultivation studiesrdquo Nether-lands Journal of Agricultural Sciences vol 5 pp 255ndash262 1957

[35] A Klute and C Dirksen ldquoHydraulic conductivity and diffu-sivityrdquo in Methods of Soil Analysis A Klute Ed pp 687ndash734American Society of Agronomy ASA SSSA Madison WisUSA 1982

[36] K Steiner and J Rockstrom Increasing Rainwater Productivitywith Conservation Tillage African Conservation Tillage Net-work Information Series No 5 ACT Harare Zimbabwe 2003


[37] A C Guzha ldquoEffects of tillage on soil microrelief surfacedepression storage and soil water storagerdquo Soil and TillageResearch vol 76 no 2 pp 105ndash114 2004

[38] K E Motsi E Chuma and B B Mukamuri ldquoRainwaterharvesting for sustainable agriculture in communal lands ofZimbabwerdquo Physics and Chemistry of the Earth vol 29 no 15-18 pp 1069ndash1073 2004

[39] P T Gicheru C K K Gachene and E K Biamah ldquoEffects oftillage and mulching on soil moisture conservation and cropproductionrdquo Applied Plant Sciences vol 12 no 1 pp 5ndash9 1998

[40] S Gursoy A Sessiz E Karademir et al ldquoEffects of ridgeand conventional tillage systems on soil properties and cottongrowthrdquo International Journal of Plant Production vol 5 no 3pp 227ndash236 2011

[41] P R Hobbs K Sayre and R Gupta ldquoThe role of conservationagriculture in sustainable agriculturerdquo Philosophical Transac-tions of the Royal Society B Biological Sciences vol 363 no 1491pp 543ndash555 2008

[42] A Karuma C K K Gachene P T Gicheru et al ldquoEffects oflegume cover crop and sub-soiling on soil properties and maize(Zea mays L) growth in semi arid area of machakos DistrictKenyardquo Tropical and Subtropical Agroecosystems vol 14 no 1pp 237ndash243 2011

[43] K P Fabrizzi F O Garcıa J L Costa and L I PiconeldquoSoil water dynamics physical properties and corn and wheatresponses to minimum and no-tillage systems in the southernPampas of Argentinardquo Soil and Tillage Research vol 81 no 1pp 57ndash69 2005

[44] M A Kabir M A Rahim D A N Majumder and T MT Iqbal ldquoEffect of mulching and tillage on yield and keepingquality of Garlic (Allium Sativum L)rdquo Bangladesh Journal ofAgricultural Research vol 38 no 1 pp 115ndash125 2013

[45] K A McVay J A Budde K Fabrizzi et al ldquoManagementeffects on soil physical properties in long-term tillage studiesin Kansasrdquo Soil Science Society of America Journal vol 70 no 2pp 434ndash438 2006

[46] K E Giller E Witter M Corbeels and P Tittonell ldquoConserva-tion agriculture and smallholder farming in Africa the hereticsrsquoviewrdquo Field Crops Research vol 114 no 1 pp 23ndash34 2009

[47] J B Passioura and J F Angus ldquoImproving productivity of cropsin water-limited environmentsrdquo Advances in Agronomy vol106 pp 37ndash75 2010

[48] W Mupangwa S Twomlow and S Walker ldquoThe influence ofconservation tillage methods on soil water regimes in semi-aridsouthernZimbabwerdquoPhysics andChemistry of the Earth vol 33no 8-13 pp 762ndash767 2008

[49] R G Moreno M C D Alvarez A T Alonso S Barringtonand A S Requejo ldquoTillage and soil type effects on soil surfaceroughness at semiarid climatic conditionsrdquo Soil and TillageResearch vol 98 no 1 pp 35ndash44 2008

[50] J Lipiec J Kus A Nosalewicz and M Turski ldquoTillage systemeffects on stability and sorptivity of soil aggregatesrdquo Interna-tional Agrophysics vol 20 no 3 pp 189ndash193 2006

[51] KKhurshidM IqbalM SArif andANawaz ldquoEffect of tillageand mulch on soil physical properties and growth of maizerdquoInternational Journal of Agriculture and Biology vol 8 no 5 pp593ndash596 2006

[52] J M Miriti G Kironchi A O Esilaba C K K Gachene LK Heng and D M Mwangi ldquoThe effects of tillage systems onsoil physical properties and water conservation in a sandy loamsoil in Eastern Kenyardquo Journal of Soil Science and EnvironmentalManagement vol 4 no 7 pp 146ndash154 2013

[53] C M P Vaz L H Bassoi and J W Hopmans ldquoContributionof water content and bulk density to field soil penetrationresistance as measured by a combined cone penetrometer-TDRproberdquo Soil and Tillage Research vol 60 no 1-2 pp 35ndash42 2001

[54] B J Atwell ldquoResponse of roots to mechanical impedancerdquoEnvironmental and Experimental Botany vol 33 no 1 pp 27ndash40 1993

[55] J R Landon Booker Tropical Soil Manual A Handbook forSoil Survey and Agricultural Land Evaluation in the Tropics andSubtropics Longman Scientific amp Technical Publishers EssexUK 1991

[56] S Husnjak D Filipovic and S Kosutic ldquoInfluence of differenttillage systems on soil physical properties and crop yieldrdquoRostlinna Vyroba vol 48 no 6 pp 249ndash254 2002

[57] T M Agbede ldquoEffect of tillage on soil properties and yam yieldon anAlfisol in southwesternNigeriardquo Soil and Tillage Researchvol 86 no 1 pp 1ndash8 2006

[58] N C Brady and R R Weil The Nature and Properties of SoilsPearson Education 13th edition 2008

[59] T Anken P Weisskopf U Zihlmann H Forrer J Jansa and KPerhacova ldquoLong-term tillage system effects under moist coolconditions in Switzerlandrdquo Soil and Tillage Research vol 78 no2 pp 171ndash183 2004

[60] J AOsunbitanD JOyedele andKOAdekalu ldquoTillage effectson bulk density hydraulic conductivity and strength of a loamysand soil in southwesternNigeriardquo Soil and Tillage Research vol82 no 1 pp 57ndash64 2005

[61] J D Jabro W B Stevens R G Evans and W M IversenldquoTillage effects on physical properties in two soils of theNorthern Great Plainsrdquo Applied Engineering in Agriculture vol25 no 3 pp 377ndash382 2009

[62] F U H Khan A R Tahir and I J Yule ldquoImpact of differenttillage practices and temporal factor on soil moisture contentand soil bulk densityrdquo International Journal of Agriculture andBiology vol 3 pp 163ndash166 1999

[63] F U H Khan A R Tahir and I J Yule ldquoIntrinsic implicationof different tillage practices on soil penetration resistance andcrop growthrdquo International Journal of Agriculture and Biologyvol 1 pp 23ndash26 2001

[64] E Gomez L Ferreras S Toresani A Ausilio and V BisaroldquoChanges in some soil properties in a Vertic Argiudoll undershort-term conservation tillagerdquo Soil and Tillage Research vol61 no 3-4 pp 179ndash186 2001

[65] R Lal and M K Shukla Eds Principles of Soil Physics MarcelDekker New York NY USA 2004

[66] N H Abu-Hamdeh ldquoSoil compaction and root distributionfor okra as affected by tillage and vehicle parametersrdquo Soil andTillage Research vol 74 no 1 pp 25ndash35 2003

[67] G N Karuku C K K Gachene N Karanja W Cornelis HVerplancke andGKironchi ldquoSoil hydraulic properties of a niti-sol in kabete Kenyardquo Tropical and Subtropical Agroecosystemsvol 15 no 3 pp 595ndash609 2012

[68] W Cheng and D C Coleman ldquoEffect of living roots on soilorganic matter decompositionrdquo Soil Biology and Biochemistryvol 22 no 6 pp 781ndash787 1990

[69] A Fan X Chen and Z Li ldquoEffects of intercropping systemof trees with soyabean on soil physico-chemical properties injuvenile plantationrdquo Journal of Forestry Research vol 17 pp226ndash230 2006

[70] C Chang and C W Lindwall ldquoEffect of long-term minimumtillage practices on some physical properties of a Chernozemic


clay loamrdquo Canadian Journal of Soil Science vol 69 no 3 pp443ndash449 1989

[71] J L Pikul Jr and J K Aase ldquoWater infiltration and storageaffected by subsoiling and subsequent tillagerdquo Soil ScienceSociety of America Journal vol 67 no 3 pp 859ndash866 2003

[72] T R Green L R Ahuja and J G Benjamin ldquoAdvances andchallenges in predicting agriculturalmanagement effects on soilhydraulic propertiesrdquoGeoderma vol 116 no 1-2 pp 3ndash27 2003

Submit your manuscripts athttpwwwhindawicom

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ClimatologyJournal of


followed by one or more harrowings The degree of soildisturbance depends on the type of implement used thenumber of passes type of soil and intended crop type[13] The most common conventional tillage practiced inKenya involves the use of hand hoes ox-drawn mould boardploughs tractor-drawn disc ploughs and harrows combinedwith straw collection and burning during land preparation[2 14] During the operation the soils are cut invertedand pulverized burying most of the residues underneath[14] Consequently in many areas especially semiarid areasconventional agriculture has led to a decline in crop yieldsand profitability when compared to those realized from areaswith higher rainfall [15]

Other sustainable techniques advocated in the semiaridareas for soil and water conservation have included tiedridging cover cropping mulching subsoiling and ripping[16 17] These techniques are referred to as conservationtillage and have the potential of soil moisture retention andmitigation of intraseasonal dry spells that often result inlow productivity and crop failure reduce soil evaporationand enable organic matter build-up which enhances waterholding capacity of the soil [18ndash20]

Conservation tillage practices are particularly importantfor increasing the productivity of water through reducingrunoff and evaporation and improving soil water storage[18] In Kenya promotion of animal-drawn conservationtillage tools such as rippers and subsoilers among smallholderfarmers has resulted in improvedwater productivity and cropyields [21 22] Although conservation tillage is highly advo-cated there is strong evidence that this kind of tillage maynot be good with soils prone to surface crusting and sealinga characteristic of most of the soils in the semiarid areas ofKenya [23ndash26] Therefore the local biophysical conditions inthe smallholder farming systems in these semiarid areas needto be considered and deliberate adaptation efforts made

The success of any tillage practices is directly related tothe improvement of the soil physical properties which in turnmay affect the growth and yield of crops due to the differentsoil conditions created In a review on the effect of soil phys-ical properties on soil moisture Strudley et al [27] showedthat bulk density porosity soil surface sealing and crustingsurface roughness hydraulic conductivity and infiltrationrates were highly influenced by different tillageTherefore thechoice of any tillage system is too critical for maintenanceof the soil physical properties necessary for crop growth[28] However the resulting effect of tillage on selectedphysical properties depends on the site-specific biophysicalenvironment such as seasonal variability in rainfall inherentsoil fertility status or the prevailing climatic conditions [29]Few studies have measured these soil physical propertiesespecially in semiarid Eastern Kenya hence the essence forthe study reported herein

Recent efforts have focused on minimum tillage prac-tices as a soil and water conservation measure [30 31]Nonetheless maize-legume cropping systems are popular inimproving land use efficiency and economic returns In orderto exploit these practices there is a need to understand theinfluence of tillage and cropping systems on selected soilphysical properties in dryland cropping systems for sustained

Table 1 Baseline chemical and physical properties of the experi-mental site (0ndash30 cm)

Soil property ValuespH (H2O) 650pH (001M CaCl2) 561C 110N 009K cmolkg 235Na cmolkg 046Ca cmolkg 231Mg cmolkg 039CEC cmolkg 670P (mgkg) 1350Sand () 2200Silt () 3900Clay () 3900Textural class Clay loamBulk density (gcm3) 127Saturated hydraulic conductivity (119870sat) (cmh) 027Saturation (cmcm3) 0664Field capacity (cmcm3) 0508Wilting point (cmcm3) 0480Plant available water (cmcm3) 0028

productivityThe objective of this study was to investigate theeffect of selected tillage practices and cropping systems onselected soil physical properties in semiarid Mwala districtEastern Kenya Specifically their effects on soil moisturesoil surface roughness crust strength saturated hydraulicconductivity bulk density and porosity

2 Materials and Methods

21 Study Site Description The study was conducted inMbiuni location Mwala district Machakos County EasternKenya (1∘151015840S 37∘251015840E) The area is characterized by lowerratic and poorly distributed bimodal rainfall that makescrop production difficult under rainfed conditions The longrains commence in mid-March and end in May while shortrains start in mid-October and end in late November Themean annual rainfall for Mwala district is 5967mm [32]Maize and beans dominate household consumption Pulsesare grown in the district and the predominant ones arebeans pigeon peas cowpeas green grams and chickpeasSoil chemical and physical properties at the site are given inTable 1 The study site was previously under beans and theslope was lt2

22 Experimental Design and Layout The trials were estab-lished in 2012 and ran for four seasons during the long (LR)(MarchndashMay) and short rains (SR) (OctoberndashDecember)(ie LR 2012 SR 2012 LR 2013 and SR 2013) The treatmentsconsisted of six tillage practices disc ploughing (DP) discploughing and harrowing (DPH) ox-ploughing (OX) handhoeing with tied ridges (HTR) hand hoeing only (H) and





CR = 119868 times ( CsAC) (1)



119870sat = 119876 times119871

(119860 times 119879 times 119867) (2)





120588119904

) (3)





































Table3Eff

ecto

ftillageo

nsoilsurfa

ceroug


s)

Tillage

Long

rains(LR

2012)

Shortrains

(SR2012)

Long

rains(LR

2013)

Shortrains

(SR2013)

Atplou

ghing

Before

plantin

g3WAP

Atplou

ghing

Before

plantin

g3WAP

Atplou

ghing

Before

plantin

g3WAP

Atplou

ghing

Before

plantin

g3WAP

H368

ab318

b271b

307

a230

a162

a345

a255

a132

a390

a313

ab268

bc

HTR

750

d725

d652

d678

d64

9d

586

c716

d626

d556

c724

c639

d560

d

DP

537

c485

c40

7c

330

ab266

ab225

a368

ab278

ab195

a571b

498

c376

c

DPH

298

a179a

135

a369

b337

b212

a40

7b

317

b182

a412

a287

a240

ab

OX

481b

c387

b321b

c46

7c

320

b170a

505

c415

c140

a511b

421b

c147

a

SSR

mdashmdash

mdash508

c472

c366

b546

c456

c336

b552

b451c

343

bc

Mean

487

419

357

4432

3788

287

481

391

257

527

435

322

LSD(5)

1209

769

1075

5212

685

812

52

52

81

905

1255

1133

CV

9465

7748

63

7844

54

87

44

31

57

TillageH

handho

eing

only

HTR

handho

eing

with

tiedrid

gesDP

disc

plou

ghingDPH

disc

plou

ghing+harrow

ingOX

ox-ploug

hing

SSR

sub

soiling

-ripping

and

(mdash)no

tmeasuredin

thatseason


inthec

olum

nsindicatesig

nificantd

ifference

at5

prob

abilitylevel


Table4Soilcruststre

ngth

asinflu

encedby

timeo

fmeasurementtillage

practicesand

thec

ropp

ingsyste

ms(119899=3season

s)

Soilcruststre

ngth

(MPa)

Shortrains

2012

Long

rains2

013

Shortrains

2013

3WAP

7WAP

10WAP

15WAP

4WAP

6WAP

10WAP

16WAP

4WAP

8WAP

12WAP

17WAP

Tillage

H10

34a

1001

1272

1269

1187

a15

5315

7414

691187

a13

5014

680747a

b

HTR

0905b

1007

1088

1124

1133

a14

9416

8015

261133

b12

8214

620672c

DP

1111

a10

5512

081193

1188

a14

7517

0814

721188

a13

4114

150728b

c

DPH

1094

a10

2312

5512

171136

a14

6016

7114

511136

b13

0114

170769a

b

OX

1136

a10

2512

5612

341175

a15

6116

7314

781175

ab13

5514

530807a

SSR

1111

a10

6712

3012

9612

09a

1568

1705

1519

1209

a13

5714

800815a

LSD5

0111

0106

0162

0088

0047

0105

0108

0069

0047

0067

0053

0072

Crop

ping

syste

mSolebean

1026

1032

1221

1241

1177

1529

1617

b14

791177

1314

1441

0756

Solemaize

1086

1006

1208

1204

1161

1530

1713

a14

821161

1338

1462

0749

Intercrop

1085

1051

1225

1222

1176

1496

1675

a14

961176

1340

1445

0765

LSD5

0072

006

40052

0036

0051

004

60047

0036

0051

0041

0029

004

8Sign

ificancelevels

Tillage

0005

0741

0218

0012

0018

0165

0160

0193

0018

0129

0085

0007

Crop

ping

syste

m0171

0369

0794

0131

0773

0245

lt0001

0571

0773

0374

0272

0798

Tillagetimescrop

ping

syste

m046

60493

040

60043

0672

0151

0789

0576

0672

0266

0278

0935

CV

32

69

52

42

1650

1728

1615

09

102

TillageH

handho

eing

only

HTR

handho

eing

with

tiedrid

gesDP

disc

plou

ghingDPH

disc

plou

ghing+harrow

ingOX

ox-ploug

hing

and

SSR

subsoilin

g-rip

ping


inthec

olum

nsindicatesig

nificantd

ifference

at5

prob

abilitylevel



















4 Conclusion





Acknowledgments


References


















































































Journal of












Volume 2014

Advances in









Geophysics


















CR = 119868 times ( CsAC) (1)



119870sat = 119876 times119871

(119860 times 119879 times 119867) (2)





120588119904

) (3)





































Table3Eff

ecto

ftillageo

nsoilsurfa

ceroug


s)

Tillage

Long

rains(LR

2012)

Shortrains

(SR2012)

Long

rains(LR

2013)

Shortrains

(SR2013)

Atplou

ghing

Before

plantin

g3WAP

Atplou

ghing

Before

plantin

g3WAP

Atplou

ghing

Before

plantin

g3WAP

Atplou

ghing

Before

plantin

g3WAP

H368

ab318

b271b

307

a230

a162

a345

a255

a132

a390

a313

ab268

bc

HTR

750

d725

d652

d678

d64

9d

586

c716

d626

d556

c724

c639

d560

d

DP

537

c485

c40

7c

330

ab266

ab225

a368

ab278

ab195

a571b

498

c376

c

DPH

298

a179a

135

a369

b337

b212

a40

7b

317

b182

a412

a287

a240

ab

OX

481b

c387

b321b

c46

7c

320

b170a

505

c415

c140

a511b

421b

c147

a

SSR

mdashmdash

mdash508

c472

c366

b546

c456

c336

b552

b451c

343

bc

Mean

487

419

357

4432

3788

287

481

391

257

527

435

322

LSD(5)

1209

769

1075

5212

685

812

52

52

81

905

1255

1133

CV

9465

7748

63

7844

54

87

44

31

57

TillageH

handho

eing

only

HTR

handho

eing

with

tiedrid

gesDP

disc

plou

ghingDPH

disc

plou

ghing+harrow

ingOX

ox-ploug

hing

SSR

sub

soiling

-ripping

and

(mdash)no

tmeasuredin

thatseason


inthec

olum

nsindicatesig

nificantd

ifference

at5

prob

abilitylevel


Table4Soilcruststre

ngth

asinflu

encedby

timeo

fmeasurementtillage

practicesand

thec

ropp

ingsyste

ms(119899=3season

s)

Soilcruststre

ngth

(MPa)

Shortrains

2012

Long

rains2

013

Shortrains

2013

3WAP

7WAP

10WAP

15WAP

4WAP

6WAP

10WAP

16WAP

4WAP

8WAP

12WAP

17WAP

Tillage

H10

34a

1001

1272

1269

1187

a15

5315

7414

691187

a13

5014

680747a

b

HTR

0905b

1007

1088

1124

1133

a14

9416

8015

261133

b12

8214

620672c

DP

1111

a10

5512

081193

1188

a14

7517

0814

721188

a13

4114

150728b

c

DPH

1094

a10

2312

5512

171136

a14

6016

7114

511136

b13

0114

170769a

b

OX

1136

a10

2512

5612

341175

a15

6116

7314

781175

ab13

5514

530807a

SSR

1111

a10

6712

3012

9612

09a

1568

1705

1519

1209

a13

5714

800815a

LSD5

0111

0106

0162

0088

0047

0105

0108

0069

0047

0067

0053

0072

Crop

ping

syste

mSolebean

1026

1032

1221

1241

1177

1529

1617

b14

791177

1314

1441

0756

Solemaize

1086

1006

1208

1204

1161

1530

1713

a14

821161

1338

1462

0749

Intercrop

1085

1051

1225

1222

1176

1496

1675

a14

961176

1340

1445

0765

LSD5

0072

006

40052

0036

0051

004

60047

0036

0051

0041

0029

004

8Sign

ificancelevels

Tillage

0005

0741

0218

0012

0018

0165

0160

0193

0018

0129

0085

0007

Crop

ping

syste

m0171

0369

0794

0131

0773

0245

lt0001

0571

0773

0374

0272

0798

Tillagetimescrop

ping

syste

m046

60493

040

60043

0672

0151

0789

0576

0672

0266

0278

0935

CV

32

69

52

42

1650

1728

1615

09

102

TillageH

handho

eing

only

HTR

handho

eing

with

tiedrid

gesDP

disc

plou

ghingDPH

disc

plou

ghing+harrow

ingOX

ox-ploug

hing

and

SSR

subsoilin

g-rip

ping


inthec

olum

nsindicatesig

nificantd

ifference

at5

prob

abilitylevel



















4 Conclusion





Acknowledgments


References


















































































Journal of












Volume 2014

Advances in









Geophysics









































Table3Eff

ecto

ftillageo

nsoilsurfa

ceroug


s)

Tillage

Long

rains(LR

2012)

Shortrains

(SR2012)

Long

rains(LR

2013)

Shortrains

(SR2013)

Atplou

ghing

Before

plantin

g3WAP

Atplou

ghing

Before

plantin

g3WAP

Atplou

ghing

Before

plantin

g3WAP

Atplou

ghing

Before

plantin

g3WAP

H368

ab318

b271b

307

a230

a162

a345

a255

a132

a390

a313

ab268

bc

HTR

750

d725

d652

d678

d64

9d

586

c716

d626

d556

c724

c639

d560

d

DP

537

c485

c40

7c

330

ab266

ab225

a368

ab278

ab195

a571b

498

c376

c

DPH

298

a179a

135

a369

b337

b212

a40

7b

317

b182

a412

a287

a240

ab

OX

481b

c387

b321b

c46

7c

320

b170a

505

c415

c140

a511b

421b

c147

a

SSR

mdashmdash

mdash508

c472

c366

b546

c456

c336

b552

b451c

343

bc

Mean

487

419

357

4432

3788

287

481

391

257

527

435

322

LSD(5)

1209

769

1075

5212

685

812

52

52

81

905

1255

1133

CV

9465

7748

63

7844

54

87

44

31

57

TillageH

handho

eing

only

HTR

handho

eing

with

tiedrid

gesDP

disc

plou

ghingDPH

disc

plou

ghing+harrow

ingOX

ox-ploug

hing

SSR

sub

soiling

-ripping

and

(mdash)no

tmeasuredin

thatseason


inthec

olum

nsindicatesig

nificantd

ifference

at5

prob

abilitylevel


Table4Soilcruststre

ngth

asinflu

encedby

timeo

fmeasurementtillage

practicesand

thec

ropp

ingsyste

ms(119899=3season

s)

Soilcruststre

ngth

(MPa)

Shortrains

2012

Long

rains2

013

Shortrains

2013

3WAP

7WAP

10WAP

15WAP

4WAP

6WAP

10WAP

16WAP

4WAP

8WAP

12WAP

17WAP

Tillage

H10

34a

1001

1272

1269

1187

a15

5315

7414

691187

a13

5014

680747a

b

HTR

0905b

1007

1088

1124

1133

a14

9416

8015

261133

b12

8214

620672c

DP

1111

a10

5512

081193

1188

a14

7517

0814

721188

a13

4114

150728b

c

DPH

1094

a10

2312

5512

171136

a14

6016

7114

511136

b13

0114

170769a

b

OX

1136

a10

2512

5612

341175

a15

6116

7314

781175

ab13

5514

530807a

SSR

1111

a10

6712

3012

9612

09a

1568

1705

1519

1209

a13

5714

800815a

LSD5

0111

0106

0162

0088

0047

0105

0108

0069

0047

0067

0053

0072

Crop

ping

syste

mSolebean

1026

1032

1221

1241

1177

1529

1617

b14

791177

1314

1441

0756

Solemaize

1086

1006

1208

1204

1161

1530

1713

a14

821161

1338

1462

0749

Intercrop

1085

1051

1225

1222

1176

1496

1675

a14

961176

1340

1445

0765

LSD5

0072

006

40052

0036

0051

004

60047

0036

0051

0041

0029

004

8Sign

ificancelevels

Tillage

0005

0741

0218

0012

0018

0165

0160

0193

0018

0129

0085

0007

Crop

ping

syste

m0171

0369

0794

0131

0773

0245

lt0001

0571

0773

0374

0272

0798

Tillagetimescrop

ping

syste

m046

60493

040

60043

0672

0151

0789

0576

0672

0266

0278

0935

CV

32

69

52

42

1650

1728

1615

09

102

TillageH

handho

eing

only

HTR

handho

eing

with

tiedrid

gesDP

disc

plou

ghingDPH

disc

plou

ghing+harrow

ingOX

ox-ploug

hing

and

SSR

subsoilin

g-rip

ping


inthec

olum

nsindicatesig

nificantd

ifference

at5

prob

abilitylevel



















4 Conclusion





Acknowledgments


References


















































































Journal of












Volume 2014

Advances in









Geophysics















Table4Soilcruststre

ngth

asinflu

encedby

timeo

fmeasurementtillage

practicesand

thec

ropp

ingsyste

ms(119899=3season

s)

Soilcruststre

ngth

(MPa)

Shortrains

2012

Long

rains2

013

Shortrains

2013

3WAP

7WAP

10WAP

15WAP

4WAP

6WAP

10WAP

16WAP

4WAP

8WAP

12WAP

17WAP

Tillage

H10

34a

1001

1272

1269

1187

a15

5315

7414

691187

a13

5014

680747a

b

HTR

0905b

1007

1088

1124

1133

a14

9416

8015

261133

b12

8214

620672c

DP

1111

a10

5512

081193

1188

a14

7517

0814

721188

a13

4114

150728b

c

DPH

1094

a10

2312

5512

171136

a14

6016

7114

511136

b13

0114

170769a

b

OX

1136

a10

2512

5612

341175

a15

6116

7314

781175

ab13

5514

530807a

SSR

1111

a10

6712

3012

9612

09a

1568

1705

1519

1209

a13

5714

800815a

LSD5

0111

0106

0162

0088

0047

0105

0108

0069

0047

0067

0053

0072

Crop

ping

syste

mSolebean

1026

1032

1221

1241

1177

1529

1617

b14

791177

1314

1441

0756

Solemaize

1086

1006

1208

1204

1161

1530

1713

a14

821161

1338

1462

0749

Intercrop

1085

1051

1225

1222

1176

1496

1675

a14

961176

1340

1445

0765

LSD5

0072

006

40052

0036

0051

004

60047

0036

0051

0041

0029

004

8Sign

ificancelevels

Tillage

0005

0741

0218

0012

0018

0165

0160

0193

0018

0129

0085

0007

Crop

ping

syste

m0171

0369

0794

0131

0773

0245

lt0001

0571

0773

0374

0272

0798

Tillagetimescrop

ping

syste

m046

60493

040

60043

0672

0151

0789

0576

0672

0266

0278

0935

CV

32

69

52

42

1650

1728

1615

09

102

TillageH

handho

eing

only

HTR

handho

eing

with

tiedrid

gesDP

disc

plou

ghingDPH

disc

plou

ghing+harrow

ingOX

ox-ploug

hing

and

SSR

subsoilin

g-rip

ping


inthec

olum

nsindicatesig

nificantd

ifference

at5

prob

abilitylevel



















4 Conclusion





Acknowledgments


References


















































































Journal of












Volume 2014

Advances in









Geophysics
































4 Conclusion





Acknowledgments


References


















































































Journal of












Volume 2014

Advances in









Geophysics
























































































Journal of












Volume 2014

Advances in









Geophysics














Research Article Tillage Effects on Selected Soil Physical...

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