KWAME NKRUMAH UNIVERSITY OF SCIENCE AND TECHNOLOGY, KUMASI, GHANA SCHOOL OF GRADUATE STUDIES DEPARTMENT OF CROP AND SOIL SCIENCES

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1 KWAME NKRUMAH UNIVERSITY OF SCIENCE AND TECHNOLOGY, KUMASI, GHANA SCHOOL OF GRADUATE STUDIES DEPARTMENT OF CROP AND SOIL SCIENCES IMPACT OF LAND USE ON NEMATODE ASSEMBLAGE IN THREE AGRO-ECOLOGICAL ZONES OF GHANA BY OBED ASIEDU BSC (HONS) AGRICULTURE NOVEMBER, 2015

2 IMPACT OF LAND USE ON NEMATODE ASSEMBLAGE IN THREE AGRO-ECOLOGICAL ZONES OF GHANA BY OBED ASIEDU (BSc. (Hons) Agriculture) A THESIS SUBMITTED TO THE DEPARTMENT OF CROP AND SOIL SCIENCES, KWAME NKRUMAH UNIVERSITY OF SCIENCE AND TECHNOLOGY, KUMASI, IN PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF PHILOSOPHY IN CROP PROTECTION (NEMATOLOGY) i

3 DECLARATION I certify tht this thesis does not incorporte, without cknowledgement, ny mteril previously submitted for degree or diplom in ny university; nd tht to the best of my knowledge nd belief, does not contin ny mteril previously published or written by nother person, except where due reference hs been mde in the text OBED ASIEDU DATE (STUDENT) PG Dr. CHARLES KWOSEH DATE (SUPERVISOR) THOMAS ADJEI-GYAPONG DATE (CO-SUPERVISOR) Dr. ENOCK A. OSEKRE DATE (HEAD OF DEPARTMENT) ii

4 ABSTRACT Understnding the types of biologicl nd nutritionl degrdtions is criticl in developing prcticl soil helth mngement strtegies in Ghn. To understnd the types of biologicl nd nutritionl degrdtions in disturbed nd undisturbed lndscpes; nd the impct of chnge in lnd use on soil physicochemicl nd biologicl properties, 90 frms (mize nd tomto gro-systems) nd nine undisturbed sites were smpled in 2012 nd 2013 from the semi-deciduous forest, forest-svnnh trnsition nd guine svnnh gro-ecologicl zones of Ghn for lbortory investigtions. Frmers were lso interviewed to scertin previling cultivtion prctices in the study res. This study used nemtode ssemblge nlysis to determine ecologicl disturbnce (PPI, MI nd ΣMI), community diversity (H, λ, N0 nd N1), nd soil food web structure (BI, CI, SI nd EI). Smples were lso nlysed for soil ph (H2O), orgnic crbon (OC) totl nitrogen (%N), vilble nitrogen (NO3 - +NH4 + ), P2O5, K2O5, C 2+, Mg 2+ nd effective ction exchnge cpcity (ECEC) to evlute the levels of physicochemicl degrdtions. Results from the lbortory nlysis of 396 nd 99 smples for physicochemicl nd biologicl properties respectively, were nlysed by Residul Mximum Likelihood (RELM) Liner Mixed Model (VSN Interntionl, 2011). Results from the study show tht the soils were inherently poor, in terms of plnt nutrients nd nturlly frgile, in terms of soil food web condition which were further worsened by cultivtion prctices. Most frmers continuously cultivted their fields for over 9 yers in the Semi-Deciduous Forest nd Forest-Svnnh Trnsition zones yet their cultivtion prctices, were not directed towrds mintining good soil helth. Soils from undisturbed sites of ll the three gro-ecologicl zones recorded significntly higher mturity index (ΣMI) thn soils from mize nd tomto fields, indicting tht the current cultivting prctices re disturbing the soil s ecosystem. iii

5 DEDICATION This thesis is dedicted to Dr. Eric Asre; my his soul rest in perfect pece. iv

6 ACKNOWLEDGEMENTS I m very grteful to the Howrd G. Buffett Foundtion for funding this reserch nd to Prof. Hddish Melkeberhn of Michign Stte University, USA, for the specil ssistnce, ptience nd motivtion during this work. I wish to thnk my supervisor, Dr. Chrles Kwoseh, for his guidnce, constructive criticisms nd intelligent inputs which mde this study success. I m lso grteful to Mr. Thoms Adjei-Gypong nd deeply moved by his solid support throughout this reserch especilly, during soil smpling nd frmer interviews. Specil thnks go to the Chief nd people of Kunkw nd ll frmers interviewed for llowing us into their frms for soil smples. I pprecite the efforts of the Fculty s drivers, Mr. Collins Asnte nd Mr. Amoh, for tking the tem sfely to the smpling sites nd bck to the university. I m lso grteful to Miss Mercy Obenewh Owusu for her love, ptience nd ssistnce during type setting of this thesis. I would lso like to thnk Mr. Osei-Akoto, Mr. Bonifce, Mr. Joe Acquh, Mr. George Nortey nd my collegue Mr. Awudu Abubkr for their efforts during the lbortory soil nlysis. v

7 Contents TABLE OF CONTENTS Pge DECLARATION... ii ABSTRACT... iii DEDICATION... iv ACKNOWLEDGEMENTS... v TABLE OF CONTENTS... vi LIST OF TABLES... x LIST OF FIGURES... xi APPENDICES... xiii CHAPTER ONE INTRODUCTION... 1 CHAPTER TWO LITERATURE REVIEW Bckground Climte nd gro-ecology of Ghn Cropping systems Cropping systems in Ghn Soil helth Soil ecosystem Role of soil orgnic mtter in soil helth Nemtodes s soil ecosystem monitoring tools Nemtode community nd soil ecologicl disturbnce (mturity indices) Diversity indices vi

8 Structure, enrichment nd chnnel indices CHAPTER THREE METHODOLOGY Study res Socio-economic dt collection Soil smpling Soil smple hndling Smple prtitioning Nemtode extrction Nemtode extrction by the try method (Coyne et l., 2007) Extrction of nemtodes by the sieving-sucrose centrifugtion method Counting of nemtodes Killing nd fixing of nemtodes Nemtode identifiction Nemtode community nlysis Mturity indices Diversity indices Structure, enrichment nd chnnel indices Soil physicochemicl nlysis Prticle size distribution nlysis Soil ph determintion Nitrte nitrogen (NO3 - N) determintion Ammonium nitrogen (NH4 + N) determintion Determintion of orgnic crbon / orgnic mtter Determintion of totl nitrogen Determintion of vilble phosphorus Determintion of exchngeble ctions vii

9 Determintion of clcium only Determintion of exchngeble potssium nd sodium Determintion of effective ction exchnge cpcity (ECEC) Dt nlysis CHAPTER FOUR RESULTS Demogrphic profile of inhbitnts of the reserch res Dominnt crop cultivtion prctices in the study res Nutritionl sttus nd physicochemicl properties of soil smples from the study res Soil rection Orgnic mtter Nitrogen Avilble P, exchngeble K, C, Mg nd N Al, H nd Effective ction exchnge cpcity (ECEC) (cmol(+)/kg) Nemtode community nlysis Nemtode diversity Ecologicl disturbnce Soil food web CHAPTER FIVE DISCUSSION Demogrphics Access to lnd nd cultivtion prctices Types nd levels of nutritionl nd physicochemicl degrdtion Level of biologicl degrdtion Nemtode community diversity Ecologicl disturbnce viii

10 5.3.3 Soil food web CHAPTER SIX CONCLUSION AND RECOMMENDATION REFERENCES APPENDICES ix

11 LIST OF TABLES Tble 2.1: Agro-ecologicl zones of Ghn... 7 Tble 2.2: Percentge distribution of mize re cultivted by durtion of fllow period in some gro-ecologicl zones of Ghn... 9 Tble 2.3: Percentge distribution of mize re by lnd preprtion nd plnting methods during the 2012 mjor seson in Ghn Tble 3.1: Annul rinfll nd length of growing period of gro-ecologicl zones nd loctions within which the study took plce Tble 3.2: Diversity indices used to chrcterize the distribution of bundnce within community Tble 4.1: Percentge distribution of frmers by selected cultivtion prctices in the Semi- Deciduous Forest, Forest-Svnnh Trnsition nd Guine Svnnh groecologicl zones x

12 LIST OF FIGURES Figure 1.1: Cusl nexus mong lnd resources, popultion, poverty nd lnd degrdtion (FAO, 2001) Figure 2.1: Indictor guilds of soil food web condition (bsl, structured, enriched) re designted nd weightings of the guilds long the structure nd enrichment trjectories re provided, for determintion of the Enrichment Index nd Structure Index of the food web Figure 3.1: Soil smples lbelled with n lphnumeric code to reflect the following: Zone, community, lnd use, Smple Replicte. Source: Mp dpted from FAO (2005) Figure 3.2: Smple prtitioning, storge nd processing Figure 4.1: Averge frm household size of selected communities in the Semi-deciduous Forest, Forest-Svnnh nd Guine Svnnh gro-ecologicl zones Figure 4.2: A= Soil ph, B = OM (%) nd C = orgnic nitrogen (%) of Mize, Tomto nd Undisturbed sites in the Semi-Deciduous Forest, Forest-Svnnh Trnsition nd Guine Svnnh gro-ecologicl zones Figure 4.3: A = Soil vilble nitrogen (NO3 - + NH4 + in mg/kg), B = P (mg/kg) nd C = K(cmol(+)/kg) of Mize, Tomto nd Undisturbed lndscpes in the Semi- Deciduous Forest, Forest-Svnnh Trnsition nd Guine Svnnh groecologicl zones Figure 4.4: A = Soil C (cmol(+)/kg), B = Mg (cmol(+)/kg) nd C = N (mg/kg) of Mize, Tomto nd Undisturbed lndscpes in the Semi-Deciduous Forest, Forest- Svnnh Trnsition nd Guine Svnnh gro-ecologicl zones Figure 4.5: Effective ction exchnge cpcity in cmol(+)/kg of Mize, Tomto nd Undisturbed lndscpes in the Semi-Deciduous Forest, Forest-Svnnh Trnsition nd Guine Svnnh gro-ecologicl zones Figure 4.6: A= Genus richness B = Hills Index (N2), C = Shnnon Index (H ), D= Simpson s Index (D) of Mize, Tomto nd Undisturbed lndscpes in the SEMI-Deciduous Forest, Forest-Svnnh Trnsition nd Guine Svnnh gro-ecologicl zones xi

13 Figure 4.7: A= Combined Mturity Index (ΣMI) B = Mturity Index of Plnt Prsitic Nemtodes (PPI), C = Mturity Index of Free-living Nemtodes (MI) of Mize, Tomto nd Undisturbed lndscpes in the Semi-Deciduous Forest, Forest- Svnnh Trnsition nd Guine Svnnh gro-ecologicl zones Figure 4.8: The soil food web stte of mize, tomto nd undisturbed lndscpes in Semi- Deciduous Forest (A), Forest-Svnnh Trnsition (B) nd Guine Svnnh (C) xii

14 APPENDICES Appendix 1: Demogrphic distribution of respondents in the vrious communities selected within the Semi-Deciduous Forest, Forest-Svnnh Trnsition nd Guine Svnnh gro-ecologicl zones. 73 Appendix 2: Nemtodes identified in mize, tomto, nd undisturbed lndscpes of the Semi-Deciduous Forest zone 74 Appendix 3: Nemtodes identified in mize, tomto, nd undisturbed lndscpes of the Forest-Svnnh Trnsition zone 75 Appendix 4: Nemtodes identified in mize, tomto, nd undisturbed lndscpes of the Guine Svnnh zone 76 Appendix 5: Rtings of soil nutrient in griculturl soils (Logthn, 1987). 77 Appendix 6: Nemtode gener imge gllery from the study 78 xiii

15 CHAPTER ONE 1.0 INTRODUCTION Crop cultivtion hs direct effects on the soil which in turn ffects frm productivity. A helthy soil offers ecosystem functions including primry productivity (plnt growth nd yield), decomposition nd nutrient cycling, disese suppression, nd biologicl control (Neher, 2010). Soil helth is, therefore, necessry for sustined productivity of griculture. Frm prctices, prt from influencing soil s physicl nd chemicl properties, disturb nd destbilize the soil ecosystem (FAO, 2001). Pton (1978) reported tht continuous disturbnce of the soil grdully degrdes the soil s biodiversity which, in turn, degrdes soil fertility nd soil helth. Crop cultivtion, therefore, becomes thret to the soil nd the future of food security. Agriculture in Ghn hs evolved over the yers from cultivtion prctices which hd miniml negtive effects on the soil to prctices which hve deleterious effects on soil helth. The fllow system hs lmost disppered s towns become more densely populted nd demnd for lnd becomes greter. In the Interior Svnnh nd Forest- Svnnh-trnsitionl zones, for exmple, most frms hve been cultivted t lest once in the lst 11 yers (Rgs et l., 2013). According to Rgs et l. (2013), insignificnt percentge of frmers in Ghn undertke gronomic prctices tht re necessry for improving soil qulity; for exmple, only 3% of mize re ws pplied with niml mnure. Only 3% of mize re ws intercropped with legumes, 1% of mize re hd cover crops, 17% of mize re ws ploughed in with crop residue, nd 11% ws plnted in mulch. Almost no 1

16 mize re ws under ny form of lnd mngement prctice tht would mintin or improve soil fertility. Some fllowing, usully for short period, is still prcticed in the Forest nd Costl Svnnh Zones, but tht is rpidly disppering due to popultion growth pressures nd greter demnd on lnd. Continuous cropping nd the limited doption of soil fertility mngement prctices put much stress on the lnd (Rgs et l., 2013). In res where frmers re reported to pply minerl fertilizers, this is done t rtes fr below the recommended. Rgs et l. (2013) reported tht even though fertilizer ppliction on mize hs significntly incresed, the ppliction rte (47 kg/h of nitrogen) is hlf the recommended (90 kg/h) despite ntionl subsidy progrmme to encourge more users nd greter rtes of ppliction on crops. Thirty-three percent of mize frmers in Ghn reported tht lck of funds or high cost of fertilizers s the reson for the non-use. Herbicide use on the other hnd, is more populr. This, ccording to Rgs et l. (2013), is s result of the influx of chep herbicides formultions from Chin to Ghn: bout 73% of frmers in mize growing res in Ghn pply herbicides t the rte of 9.2 L/h which is higher thn the recommended rte. Lnd shortge, poverty, non-sustinble lnd mngement prctices, together with climte chnge impir the struggle for food security. Identifying the root cuses of degrdtion of frm lnds is key in mitigting poverty nd hunger. This would id in the development strtegies more relevnt nd prcticl to the smllholder frmer in improving soil helth nd fertility. Mwngi (1996) reported tht Afric would hve the world s lrgest net deficit in cerels, both in bsolute nd in reltive terms by With popultion continuously 2

17 nd rpidly incresing in ll prts of Afric, the need to reverse these declining trends hs become urgent. Improving soil fertility could trigger rurl nd ntionl economic development, chieve long-term food security nd improve frmers stndrds of living, whilst mitigting environmentl degrdtion nd rurl migrtion. Identifying the types of humn-induced lnd degrdtion s well s their cuses, including the relted socio-economic fctors, is prime requirement for developing mitigtion technologies. Figure 1 below, illustrtes how the indirect cuses of lnd degrdtion re ssocited with ech other. Continuous popultion increse nd increse in food demnd hve plced tremendous pressure on lnd. Poverty nd lnd tenure problems which re prevlent in developing countries hve pushed the priority of lnd mngement prctices to the bckground in recent times ( (FAO, 2001). Lnd Shortge Lnd Degrdtion Poverty Non Sustinble Lnd Mngement Prctices Figure 1.1: Cusl nexus mong lnd resources, popultion, poverty nd lnd degrdtion (FAO, 2001). Studying the diversity, distribution nd behviour of soil microorgnisms is importnt in understnding soil helth. Soil nemtode communities cn provide unique informtion bout mny spects of soil processes nd cn provide holistic mesure of the biotic nd functionl sttus of soils (Ling et l., 2005). 3

18 There re pieces of evidence of increse in poor cultivtion prctices in Ghn which threten soil helth nd, in turn, threten the future of griculture nd food security. However, informtion on the impct of crop cultivtion on soil ecosystem in Ghn is very scnty, though technologies re vilble to cpture this informtion. Indequte informtion on soil ecosystem hs led to one-size-fits-ll pproch in tckling most biologiclly degrded soils which hve severl limittions s every type of biologiclly degrded soil requires unique mngement strtegies to recover, improve, or mintin the soil, depending on the level of degrdtion. Soil nemtode community nlysis offers good opportunity for studying the impct of cultivtion prctices on soil ecosystems. This reserch focused on studying physicochemicl properties of soils nd nlysed existing nemtode communities to scertin the extent of nutritionl nd biologicl degrdtion of the soils. The min objective of this study ws to estblish the impct of cultivtion prctices in Ghn on soil nemtode community, nd the nutritionl nd physicochemicl properties of soils of mize nd tomto gro-ecosystems. The specific objectives were to: i. outline the griculturl prctices cross three gro-ecologicl zones of Ghn, ii. estblish the levels of nutritionl nd physicochemicl degrdtions cross the three gro-ecologicl zones of Ghn, nd iii. determine the level of biologicl degrdtion in cultivted soils using nemtode community nlysis. 4

19 The bove objectives were formulted bsed on the hypothesis tht lnd cultivtion prctices in Ghn re not directed towrds improving soil helth nd tht this hs led to biologicl, physicochemicl nd nutritionl degrdtion of the soils. 5

20 CHAPTER TWO 2.0 LITERATURE REVIEW 2.1 Bckground The foundtion of food security nd globl ecosystem lies in the biologicl, physicochemicl, nutritionl nd structurl helth of soil in nturl, mnged nd disturbed ecosystems (Melkeberhn, 2010). An overview of the level of biologicl, physicochemicl nd nutritionl degrdtion is key to sustinbly reversing the current trend of drop in soil fertility nd helth. Melkeberhn (2013) suggested tht the onesize-fits-ll pproch to soil-driven needs to be reconsidered. There is the need to understnd the mjor plyers in soil helth nd the reltionship mong these mjor plyers in order to design soil mngement prctices directed towrds given scenrio. 2.2 Climte nd gro-ecology of Ghn Ghn is 239,469 km 2 nd locted in West Afric on the Gulf of Guine Cost. Ghn lies within ltitudes 4 o 30 N nd 11 o N, nd longitudes 1 o 12 E nd W. The climte of Ghn is tropicl monsoon, nd strongly influenced by Inter Tropicl Convergence Zone (ITCZ), which gives rise to lternte wet nd dry sesons (Stnturf et l., 2011). Sesonl vritions in temperture in Ghn re gretest in the northern prt, with highest tempertures in the dry seson (April to June) t C, nd lowest in July to September t C. In the Southern prt, tempertures rech C in the wrmest seson (Jnury to Mrch), nd C t their lowest in July to September (McSweeney et l., 2010). Ghn is divided into six gro-ecologicl zones (Tble 2.1). A bimodl rinfll pttern in the Rin Forest, Deciduous Forest nd Forest-Svnnh Trnsition Zones results in 6

21 mjor nd minor sesons, in contrst to single growing seson in the Guine Svnnh nd Sudn Sudn Svnnh Zones, resulting from unimodl rinfll distribution. The rinfll generlly decreses from the south to the north with the wettest being the extreme south-western prt (Rin Forest Zone) of the country receiving over 2,000 mm rinfll per nnum, s compred to 1100 mm in the extreme north nd 750 mm in the south-estern costl tip (Oppong-Anne, 2006). Tble 2.1: Agro-ecologicl zones of Ghn Agro-ecologicl Are Averge nnul Growing period (dys) zone (km 2 ) rinfll (mm) Mjor seson Minor seson Rin Forest 9, Deciduous Forest 66, Trnsitionl zone 8, Costl Svnnh 4, Guine Svnnh 147,900 1, Sudn Svnnh 2,200 1, Source: (FAO, 2005). 2.3 Cropping systems A wide rnge of cropping systems exists in Ghn. At one end of the rnge is n interventionist pproch, in which most spects of production re controlled by technologicl interventions such s soil tilling, protective or curtive pest nd weed control with grochemicls, nd the ppliction of minerl fertilizers for plnt nutrition. At the other end re production systems tht tke predominntly ecosystem pproch nd re both productive nd more sustinble (Dorn nd Zeiss, 2000). These groecologicl systems re generlly chrcterized by miniml disturbnce of the nturl environment, plnt nutrition from orgnic nd non-orgnic sources, nd the use of both 7

22 nturl nd mnged biodiversity to produce food, rw mterils nd other ecosystem services. Crop production bsed on n ecosystem pproch sustins the helth of frmlnd lredy in use, nd cn regenerte lnd left in poor condition by pst misuse (Dorn nd Zeiss, 2000). FAO (2011) rgues tht irrespective of locl conditions, frm prctices generlly ssocited with conservtion griculture re necessry to ensure productivity, socioeconomic nd environmentl benefits. These prctices need to: minimize soil disturbnce by minimizing mechnicl tillge in order to mintin soil orgnic mtter, soil structure nd overll soil helth; enhnce nd mintin protective orgnic cover on the soil surfce, using crops, cover crops or crop residues, in order to protect the soil surfce, conserve wter nd nutrients, promote soil biologicl ctivity nd contribute to integrted weed nd pest mngement; cultivte wider rnge of plnt species both nnuls nd perennils in ssocitions, sequences nd rottions tht cn include trees, shrubs, pstures nd crops, in order to enhnce crop nutrition nd improve system resilience Cropping systems in Ghn In Ghn, griculture used to be dominted by shifting cultivtion (Lnd rottion), but the increse in demnd for food nd the limited ccess to lnd for food production; both resulting from the continuously incresing humn popultion, hs led to the intensifiction of griculture nd the continuous cultivtion of prcels of lnd seson fter seson (Bohen et l., 2007). A survey by Rgs et l. (2013) reveled tht in the Svnnh nd Trnsitionl zones of Ghn, most frms hve been cultivted continuously for 11 yers. They concluded tht the fllow system hs lmost disppered nd towns hve become more densely populted (Tble 2.2). 8

23 Tble 2.2: Percentge distribution of mize re cultivted by durtion of fllow period in some gro-ecologicl zones of Ghn Agro-ecologicl zones Durtion of fllow period in yers 1 > % % % % % Forest Trnsitionl Northern Svnnh Costl Svnnh Source: Rgs et l. (2013) With regrd to the bove scenrio, conscious soil mngement strtegies nd proper soil mendment pplictions re necessry for good soil helth nd sustinble food production. On the contrry, poor soil mngement prctices nd indequte fertilizer ppliction hve been reported. For exmple, the current verge ppliction rte (47 kg/h of nitrogen) is hlf the recommended (90 kg/h) despite ntionl subsidy progrmme to encourge more users nd greter rtes of ppliction on mize (Rgs et l., 2013). Tble 2.3 gives vivid illustrtion of the generl overview of poor soil mngement prctices tht exist cross the gro-ecologicl zones of Ghn. Appliction of niml mnure, ploughing in of crop residue, intercropping with nitrogen-fixing crops, plnting in mulch, crop rottion which re ll prctices which enhnce soil helth nd fertility re generlly on the low side. 9

24 Tble 2.3: Percentge distribution of mize re by lnd preprtion nd plnting methods during the 2012 mjor seson in Ghn Mngement prctices Forest Agro-ecologicl zones Trnsitionl Northern Svnnh Costl Svnnh % % % % Applied niml mnure Ploughed in crop residue Prcticed ridging Intercropped with nitrogenfixing crops Intercropped with ny crops Plnted in mulch Prcticed rely cropping or crop rottion Source: (Rgs et l., 2013) It hs been emphsized tht griculture in Ghn hs net negtive effect on soil helth nd fertility which clls for criticl nd comprehensive cross discipline pproch in hndling the sitution. This would llow for the development of prcticble technologies compctible with the opertions of smll holder frmers. 2.4 Soil helth Helthy soils re the foundtion of sustinble griculturl production. The underlying principle in the use of the term soil helth is tht soil is not just growing medium, rther it is living nd dynmic system which contins one of erth s most diverse ssemblge of living orgnisms linked together by complex food web; nd cn either 10

25 be sick or helthy, depending on the structure of the soil ecosystem. A bsic soil food web hs similr structure to food webs of other environments (FAO, 2011; Neher, 2010; Wikipedi, 2014). According to FAO (2008), soil helth is defined s the cpcity of soil to sustin biologicl productivity, mintin environmentl helth, nd promote plnt, niml, nd humn helth. Ecosystem functions offered by helthy soil include primry productivity (plnt growth nd yield), decomposition nd nutrient cycling, disese suppression, nd biologicl control (Neher, 2010). Soil orgnic mtter serves s the fuel tht powers the soil ecosystem mchinery. Prctices which promote orgnic mtter build-up re necessry for soils to be helthy. Undisturbed soils such s soils under forest, bush or grsslnds re helthy with its ecosystem in equilibrium. Such soils hve lot of orgnic mtter which builds up over mny yers. Within 10 yers fter opening virgin lnd for cultivtion, more thn hlf the orgnic mtter is lost (IIRR nd ACT, 2005). A helthy soil upon disturbnce is better positioned to recover its helth sttus nd phenomenon referred to s soil resilience. Continuous soil perturbtion grdully reduces soil resilience until point is reched when the soil cn no longer recover to helthy sttus. At this point, the soil is sid to be degrded (Pton, 1978). A number of gronomic prctices hve deleterious effect to soil helth. FAO (2011) suggests tht griculture must, literlly, return to its roots by rediscovering the importnce of helthy soil, drwing on nturl sources of plnt nutrition, nd using minerl fertilizer wisely. Soil cultivtion in itself disturbs nd destbilizes the soil ecosystem. This thretens soil helth if conscious efforts re not mde to improve the soil s helth (FAO, 2001). The soil s ecosystem is cpble of restoring its helth sttus if left to rest nd/or when soil 11

26 mngement prctices re tilted towrds the improvement or mintennce of good soil helth. Continuous disturbnce of the soil grdully degrdes the soil s biodiversity until point is reched where the soil is incpble of restoring its biot. Soil cultivtion, therefore, hs resulted in vrious levels of biologicl, physicochemicl nd nutritionl degrdtions of soils. 2.5 Soil ecosystem Role of soil orgnic mtter in soil helth Soil orgnic mtter encompsses the soil biot, nd plnt nd niml tissues t vrious stges of decomposition. Crwsell nd Lefroy (2001) reported tht the most importnt component of soil orgnic mtter is humus, the well-decomposed, drk-coloured orgnic mteril in soil. Soil orgnic mtter ffects the physicl nd chemicl properties of the soil nd its overll helth. Orgnic mtter decomposition nd rte of decomposition ffect: the soil structure nd porosity; the wter infiltrtion rte nd moisture holding cpcity of soils; the diversity nd biologicl ctivity of soil orgnisms; nd plnt nutrient vilbility (Bot nd Benites, 2005). Soil orgnic mtter hs centrl role in sustinble lnd mngement, but perspectives of role of soil orgnic mtter differs widely mong frmers, consumers, scientists nd policy mkers (Crwsell nd Lefroy, 2001). Tropicl soils re not necessrily lower in orgnic mtter content thn temperte soils but, with the exception of wetlnd rice soils, griculturl intensifiction, through clering nd clen cultivtion of soils for nnul cropping lmost universlly cuses decline in soil orgnic content (Greelnd et l., 1992). 12

27 2.5.2 Nemtodes s soil ecosystem monitoring tools Soil nemtodes occupy key position in soil ecosystem nd ply centrl role in the soil food web (Ritz nd Trudgill, 1999). Nemtode community nlysis is powerful tool for studying soil food webs. This mkes nemtodes good bio-indictors for studying the soil ecosystem in terms of soil biodiversity nd mturity mong others. In ddition, they cn be cptured nd enumerted by stndrdized extrction procedures nd re redily identified from morphologicl nd ntomicl chrcters. Further, since their feeding hbits re clerly relted to orl structure, their trophic roles re redily inferred. Ech soil smple contins n bundnce nd diversity of nemtodes nd, consequently, hs high intrinsic informtion vlue (Bongers, 1999; Bongers nd Bongers, 1998; Bongers nd Ferris, 1999; Yetes et l., 1993). The bove qulities mke nemtodes preferred cndidtes when studying the soil ecosystem. Nemtode bundnce nd the composition of nemtode ecosystems hve served s soil helth indictors in different environments (Neher, 2001). Sánchez-Moreno et l. (2006), in investigting the effect of soil mngement on soil food webs, linked soil properties nd nemtode community composition. It ws concluded from their study tht; different tillge prctices nd cropping systems determine the soil properties nd thus nemtode bundnce. Soil nemtode funl nlysis provides indices condensed with informtion regrding the structure nd composition of nemtode communities. Soil helth nd qulity cn be inferred from such indices by ssuming tht communities with different structure nd composition function differently. Thus, these indices cn be instrumentl in monitoring soil nd sediment qulity s well s ssessing ecosystem sustinbility nd biodiversity (Neher nd Drby, 2006). 13

28 Nemtode community nd soil ecologicl disturbnce (mturity indices) Mturity indices re bsed on the principle tht different tx of nemtodes hve different levels of sensitivity to stress nd re used s mesure of the ecologicl successionl sttus of soil. This contrsting sensitivities re s result of vrying lifehistory chrcteristics of different tx of nemtodes. Nemtode tx mturity indices, therefore, serve s mesure of the ecologicl successionl sttus of soil community. (Neher nd Drby, 2006). The index is represented by colonizer-persister (c-p) vlue tht rnges from colonizer (c-p = 1) to persister (c-p = 5) with the index vlues representing life-history chrcteristics ssocited with r- nd K-selection, respectively. Those with c-p = 1 re r-selected or colonizers, with short genertion times, lrge popultion fluctutions, nd high fecundity. Those with c-p = 5 re K-selected or persisters, produce few offspring, nd generlly pper lter in succession (Bongers nd Ferris, 1999). Nemtode tx with c-p = 1 re considered enrichment opportunists s their popultion densities increse rpidly in response to dditives of nutrients to soil nd my not necessrily reflect long-term chnges in soil ecologicl condition (Neher nd Drby, 2006). A mturity index for free-living nemtodes (MI) tkes into considertion ll free living nemtodes, with smller vlues being indictive of more disturbed environment. Other vrints of mturity index which vry in sensitivity, re used to indicte the level of ecologicl disturbnce of the soil ecosystem. MI25 (free-living nemtodes excluding nemtodes with cp=1) differentites MI-decrese cused by enrichment (Neher nd Drby, 2006). Mturity index clcultion which tkes into considertion only plnt prsitic nemtodes (PPI) my (Neher nd Cmpbell, 1994) or my not (Bongers et l., 1997) correlte positively with MI. 14

29 Diversity indices Diversity integrtes number of tx (richness) nd equitbility mong tx (evenness) (Hurlbert, 1971). A generlized diversity index outlined by Good (1953), incorportes richness nd evenness into single vlue tht generlly increses with both richness nd evenness; S H(α, β) = p i α { ln(p i )} β i=1 Where pi is the reltive bundnce of txon i, S is the totl number of tx present, nd α nd β define structurl ttributes of the lgorithm. Shnnon s diversity index cn be interpreted s vrint of Good s diversity index using vlues of 1 nd 1 for α nd β, respectively (or H(1,1)). Simpson index cn be interpreted s H(2,0). Shnnon nd Simpson indices re influenced by rre nd common nemtode tx respectively (Neher, 2001). Hill s diversity numbers N0, N1 nd N2 re defined s numbers of ll tx, bundnt tx, nd very bundnt tx, respectively (Ludwig nd Reynolds, 1988). N1 is clculted s n ntilog of Shnnon index, nd N2 equls the reciprocl of Simpson index. N0 equtes to tx richness by simple count of tx irrespective of their bundnce. Hill s fmily of diversity numbers re esy to interpret ecologiclly becuse the indices define units s tx (Neher, 2001) Structure, enrichment nd chnnel indices These indices re descriptors of the soil s food web condition. Soil nemtode community lso provides informtion on two mjor chrcteristics of the soil environment nd its resident communities. One chrcteristic is the flow of resources 15

30 into the food web system s indicted by enrichment opportunist species; the other is the trophic connectnce of the system s indicted by prevlence nd bundnce of higher trophic level orgnisms. (Neher nd Drby, 2006). A grphic representtion of the funl profile indictes whether the soil community is enriched but unstructured (Qudrt A), enriched nd structured (Qudrt B), resourcelimited nd structured (Qudrt C), or resource-depleted with miniml structure (Qudrt D) (Fig. 2) Figure 2.1: Indictor guilds of soil food web condition (bsl, structured, enriched) re designted nd weightings of the guilds long the structure nd enrichment trjectories re provided, for determintion of the Enrichment Index nd Structure Index of the food web. Source: (Neher nd Drby, 2006). 16

31 CHAPTER THREE 3.0 METHODOLOGY 3.1 Study res The study ws conducted in three of the six gro-ecologicl zones of Ghn; between ltitudes 4 o 44 N nd 11 o 11 N, nd longitudes 3 o 11 W nd 1 o 11 E. The gro-ecologicl zones chosen were the Semi-Deciduous Forest, Forest-Svnnh Trnsition nd Guine Svnnh gro-ecologicl zones (Tble 3.1). Loctions chosen within the zones for this study were done such tht loctions within djcent gro-ecologicl zones were t lest 70 km longitudinlly prt. Communities within given gro-ecologicl zone were selected such tht they were t lest 40 km prt. Tble 3.1: Annul rinfll nd length of growing period of gro-ecologicl zones nd loctions within which the study took plce Agro-ecologicl zone Semi- Deciduous Forest Forest- Svnnh Trnsition Guine Svnnh Annul Rinfll (mm) Length of Growing Period (dys) Reserch Loctions Kwso Nkwkw Nyinhin Amntin Nkornz Subinj Lngbinsi Nmnsi Kunkw, Mushio Adpted from FAO (2005) 17

32 The three gro-ecologicl zones covered four dministrtive regions of Ghn, nmely; Ashnti, Estern, Brong Ahfo nd Northern regions. The Ashnti nd Estern regions fll within the Semi-Deciduous Forest. The Brong Ahfo nd Northern regions fll within the Forest-Svnnh Trnsition nd Guine Svnnh gro-ecologicl zones, respectively. The inhbitnts of communities selected in Ashnti, Brong Ahfo nd Estern regions were twi speking whilst those selected in the Northern region were predominntly Mmprusis. Tomto (Solnum lycopersicum) nd mize (Ze mys) grosystems were the focus of this reserch. For uniformity, the mjor soil groups Acrisols were smpled in Semi- Deciduous Forest nd Lixisols in the Forest-Svnnh Trnsition nd Guine Svnnh zones. Within ech gro-ecologicl zone, 15 mize frms, 15 tomto frms nd three undisturbed sites were smpled (Fig. 3.1). A totl of 90 frms (30 from ech zone) nd nine undisturbed sites were smpled; four replicte soil smples were tken from ech frm for nemtode community nd physiochemicl nlyses. Ech replicte smple ws bulked from five uger smples rndomly tken from 10 x 10m qudrt. A structured questionnire ws dministered to ech frmer for socioeconomic dt. A grnd totl of 369 smples were obtined nd for the nemtode community nd physicochemicl nlysis. The smples were lbelled with lphnumeric codes to reflect the zone, community, lndscpe nd repliction number (Fig. 3.1) 18

33 Figure 3.1: Soil smples lbelled with n lphnumeric code to reflect the following: Zone, community, lnd use, Smple Replicte. Source: Mp dpted from FAO (2005) Socio-economic dt collection Frmers were interviewed to extrct informtion on soil mngement prctices. Questionnire lso touched on frm household size nd income. Ninety frmers were interviewed. The questionnire (Appendix 5) ws designed to get informtion on: Frmer demogrphics nd frm history Cultivtion prctices Soil Amendment ppliction Biocide ppliction Frm yield nd income Soil smpling Four soil smples were tken from ech frm nd ech undisturbed site. Four rndomly locted m qudrts were demrcted on ech frm nd ech undisturbed site. Within ech qudrt, 5 core soil smples were tken t depth of 0 20 cm with soil 19

34 uger nd mixed thoroughly to obtin composite smple from which g ws tken to represent tht qudrt, using Grmin GPS hndset. The GPS coordintes were tken from the centre of ech qudrt. The temperture of the soil ws lso recorded within ech qudrt with digitl soil thermometer. Detils of ech smple (e.g. smple code, GPS coordintes, soil temperture t smpling) were recorded on smple sheet ttched to the questionnire of the frmer from whose frm the smple ws tken Soil smple hndling Smples from the field were immeditely plced in lbelled plstic bgs with detiled smple codes s explined bove (Figure 3.1). Soil smples were then stored on ice until they rrived the sme dy t the Deprtment of Crop nd Soil Sciences, KNUST, where they were further stored t 10 o C for prtitioning the following dy Smple prtitioning Smples were sieved independently through 2 mm sieve mesh to remove stones nd debris. Three hundred millilitres of ech smple ws submitted to the Soil Science lbortory of the Deprtment of Crop nd Soil Sciences, KNUST for physicochemicl nlyses. About 200 cc of ech smple ws sved for nemtode extrction nd the remining 200 ml ws stored s bckup t 10 o C in refrigertor. Figure 3.2 shows how smples were prtitions by volume nd the purposes ech smple. Precutionry mesures were tken from smpling to extrction nd nlysis to void contmintion, mixing nd mislbelling of smples. Smpling nd mixing tools were clened before new smples were tken. Sieves were clened thoroughly with wter before ech smple ws sieved. Lbelling ws strictly dhered to void mix-ups. 20

35 Smples plced in plstic bgs, plced in iced continers nd trnsported to the lbortory Ech smple (~700 cc) mixed nd sieved through 2 mm sieve Nemtode (~200 cc) Physicochemicl nd Nutritionl Anlysis (~300 cc) Bck up (~200 cc) Extrction & Fixtion Counted Identified Soil Proprty (~200 cc) NH 4+ -N & NO 3- -N (~100cc) Store Nemtode community Anlysis Air Drying Soil Science Lb. Freeze Soil Science Lb. Anlysis Anlysis Figure 3.2: Smple prtitioning, storge nd processing. 3.2 Nemtode extrction Two extrction methods were employed to efficiently extrct nemtodes from the soil smples. The extrction try method (Coyne et l., 2007) ws used in tndem with the sieving-sucrose centrifugtion method (Vn Bezooijen, 2006) to ensure efficient extrction of both sluggish nd mobile nemtodes Nemtode extrction by the try method (Coyne et l., 2007) Two-ply pper npkins were plced in plstic bsket (18 cm dimeter; 6.5 cm deep) such tht the entire bse of the bsket ws covered by the pper npkin. About 100 ml of thoroughly-mixed nd sieved soil smple ws mesured, using 100 ml beker. The mesured soil smple ws then plced nd spred gently on the pper npkins in the bsket to void spill-over of soil. 21

36 The bsket with the soil smple ws stcked in n identicl bsket nd then plced in n extrction plte (20 cm dimeter; 3 cm deep). 200 ml of tp wter ws gently dded to the setup vi the gp between the edge of the plte nd the edge of the bsket. The setup ws left in the drk for 48 h. Setups were periodiclly monitored to ensure tht pltes drying out were topped up with wter. After 48 hours, the solution in the extrction plte ws poured into lbelled beker nd the plte rinsed with wsh bottle into the beker Extrction of nemtodes by the sieving-sucrose centrifugtion method The leftover soil smple from the extrction try method ws mixed in 500 ml wter by pouring between bekers ten times. Residues in the second beker ws rinsed into the beker with the smple which ws then swirled nd llowed to stnd for 15 seconds to llow snd prticles to settle. The superntnt ws poured through 833 μm / 25 μm stcked sieve nd gently tpped to fcilitte dringe. Hevy soil prticles were left behind in the beker nd debris were cught by the 833 μm sieve which were ll discrded. Using corse-spry wsh bottle, the content of the 25 μm sieve ws wshed crefully into one sector of the sieve nd then wshed with fine spry in lbelled 50 ml centrifuge tube. The contents of the centrifuge tubes were equlised to the 50 ml mrk on the centrifuge tube with tp wter nd then plced in centrifuge in four pirs. Smples were spun t 1700 rpm for five minutes without brke nd llowed to settle for five minutes. The superntnt ws spirted to pproximtely 1 cm bove the pellet. Centrifuge tubes were then topped up to 50 ml with sucrose solution; which ws prepred by dissolving 454 g of sugr in 1 litre of distilled wter t room temperture. Pellet t the bottom of tube ws completely dispersed by breking up the pellet nd 22

37 stirring using sptul. The mixture ws spun gin by ccelerting centrifuge from zero rpm to 1000 rpm in 30 sec fter which brke ws pplied. The superntnt ws poured through 25 μm sieve nd nemtodes trpped in the sieve were crefully trnsferred into lbelled vils Counting of nemtodes Nemtode liquots derived from the extrction try nd sieving-sucrose centrifugtion methods for ech smple ws combined nd diluted to 100 ml nd mixed thoroughly by swirling nd gentle shking. Pipette ws used to tke 5 ml from the middle of the liquot fter mixing by lterntively sucking nd pumping 4 times. The 5 ml liquot ws poured into clen counting try nd counted under n inverted compound microscope t mgnifiction of 20; with the id of tlly counter. Counting ws repeted twice unless the difference between counts exceeded two, where counting ws repeted third or fourth time nd the men subjected to the formul (Coyne et l., 2007) below to estimte the popultion density of nemtodes of prticulr frm. N vol = ( v2 100 n1) v1 v3, (Coyne et l., 2007) With n1 = number of nemtodes in v1 (nem/5 ml) v1 = volume (ml) of the counted suspension from v2 (5 ml) v2 = volume (ml) of the extrcted smple totl suspension (100 ml) v3 = volume (ml) of the of soil smple (100 ml) Killing nd fixing of nemtodes All four nemtode suspensions from ech frm/site were combined nd concentrted by pssing the suspension through 25 μm mesh sieve. Nemtodes in the sieve were then gently wshed with fine spry of wter into lbelled tube, ensuring tht 23

38 nemtode suspension of volume of bout 2.5 ml ws obtined. This ws done to ensure high concentrtion of nemtode suspension. Killing nd fixing of nemtodes ws done by the hot fixtive method. The fixtive used ws solution of formlin (37% formldehyde), glycerol nd distilled wter t the rtio of 10:1:89 (Coyne et l., 2007). The fixtive ws heted to bout 70 by heting in test tube immersed in ner boiling wter. A portion of the fixtive ws chilled to bout 4. About 3 ml of the hot fixtive ws dded to nemtode suspension, followed by n immedite ddition of bout 3 ml of the chilled fixtive (Vn Bezooijen, 2006). The vils were tightly closed to prevent the evportion of the fixtive Nemtode identifiction Nemtodes were identified with the id of 3030 ACCU-SCOPE Microscope equipped with 3.2 megpixel CMOS colour cmer connected to computer. Two millilitres of nemtode suspension were trnsferred into counting try fter thoroughly mixing by lterntively sucking nd pumping four times, nd then viewed under the inverted microscope. One hundred nemtodes were identified to the genus level by viewing nd compring with reference imges. Nemtodes which were not esily identified were picked unto slides nd with the CMOS colour cmer, their imges tken for further creful identifiction. Reference imges (C.I.H, 1900; Luc et l., c2005; Jirjpuri nd Ahmed, 1992) were used for the identifiction of the nemtodes. Nemtodes were clssified by trophic groups prescribed by Yetes, et l. (1993). With this clssifiction, the identified nemtodes were grouped into; plnt prsitic, fungivorous, bcterivorous, omnivorous nd predtors. Within ech trophic group, nemtode gener were further ssigned colonizer-persister (c-p) vlue ccording to Bongers (1999). The c-p vlue rnged from c-p = 1 to c-p = 5. Those with c-p = 1 re r-selected or colonizers, with short genertion times, lrge popultion fluctutions, nd 24

39 high fecundity. Those with c-p = 5 re K-selected or persisters, produce few offspring, nd generlly pper lter in succession (Bongers nd Ferris, 1999) Nemtode community nlysis Bsed on the number of nemtode gener nd their frequencies in ech smple, the following indices were clculted Mturity indices Mturity indices were clculted s weighted men frequency of nemtode gener (Neher nd Drby, 2006) t given site to determine the level of ecologicl disturbnce of the soil community of frm or undisturbed site. The mturity index ws clculted s follows. n=100 v i f i n Mturity Index = i=1, (Neher nd Drby, 2006) where, v i = c-p vlue ssigned to genus; f i = frequency of genus i in smple; n = totl number of individuls in smple. Four vrints of the mturity index were clculted for ech nemtode community. Mturity index of free-living nemtodes only, ll five c-p vlues (MI) Mturity index of free-living nemtodes only, excluding nemtodes with c- p=1 (MI25) Mturity index of plnt prsitic nemtodes only (PPI) ΣMI25 (combined free-living nd plnt-prsitic nemtodes without c-p= 1) 25

40 Diversity indices Tble 3.2: Diversity indices used to chrcterize the distribution of bundnce within community Diversity Index Formule Reference Shnnon (H ) ΣP i (ln P i ) (Shnnon nd Wever, 1949) Simpson (λ) ( n i N ) 2 (Simpsom, 1949) Hills N1 exp[ ΣP i (lnp i )] Hills N2 1 ( n i N )2 (Hill, 1973) Genus Richness (Hills N0) Number of gener N = Totl number of gener per smple = 100 ni = i th genus Pi = proportion of gener i in the totl nemtode community Structure, enrichment nd chnnel indices The structure index is n indictor of food web stte ffected by stress or disturbnce. Enrichment index is mesure of opportunistic bcterivore nd fungivore nemtodes. Chnnel index indictes the predominnt decomposition pthwys. The three indices were clculted s follows (Neher nd Drby, 2006). Structurl index (SI) = 100 s s + b Enrichment index (EI) = 100 e e + b Fu 2 W 2 Chnnel index (CI) = 100 B 1 + W 1 + Fu 2 W 2 26

41 Where, b = (B2 + Fu2) W2 where W2 = 0.8, e = (B1W1) + (Fu2W2) where W1.= 3.2 nd W2 = 0.8 s = (BnWn)+ (CnWn) + (FunWn) + (OmnWn) where n = 3-5, W3= 1.8, W4= 3.2, W5= Soil physicochemicl nlysis Soil prticle size distribution, ph, orgnic crbon, totl nitrogen, nitrte-nitrogen, mmonium-nitrogen, phosphorus, potssium, clcium, nd mgnesium for ech of the 396 smples were determined t the Soil Science lbortory of the Deprtment of Crop nd Soil Sciences, KNUST, Kumsi. All nlyticl methods used were s prescribed by Mostsr nd Roy (2008) with slight modifictions where necessry Prticle size distribution nlysis Prticle size distribution ws determined by the hydrometer method (Bouyoucos, 1962). Fifty one grmmes of ir-dried soil ws weighed into shking bottle. Fifty millilitres of 5% Sodium hexmethphosphte solution nd 100 ml distilled wter were dded; nd the suspension shken with mechnicl shker t 300 rpm for 60 min. The stirred mixture ws then trnsferred into 1 L mesuring cylinder. Distilled wter ws dded to the 1 L mrk fter plcing the hydrometer into the suspension. The hydrometer ws removed nd the suspension shken vigorously, then plced on lbortory bench. After 20 seconds, the hydrometer ws crefully reinserted into the suspension nd red (H1) t the end of 40 seconds fter shking. Temperture of the suspension (T1) ws lso recorded by inserting thermometer into the suspension. Suspension ws reshken nd kept on bench undisturbed. A second hydrometer reding (H2) ws tken two hours lter nd temperture of the suspension (T2) recorded. The percentge cly, snd nd silt were clculted s follows: 27

42 Percentge Cly= H 2+[(T 2 20) 0.36] 100 W Percentge Snd = 100 ( H 1+[(T 1 20) 0.36] W Percentge Silt = 100 (% Snd + % Cly) where; H1 = hydrometer reding t 40 seconds T1 = temperture of solution t 40 seconds H2 = hydrometer reding t two hours T1 = temperture of solution t two hours W = weight of dry soil Soil ph determintion 100) Soil ph ws determined with Eutech P700 ph meter clibrted with two buffer solutions of ph 7.0 nd ph 4.0. A 10 g soil smple ws weighed into 100 ml beker nd 10 ml distilled wter ws dded. The suspension ws stirred thoroughly with mgnetic stirrer for 30 min nd ph ws red by immersing the ph meter electrode into the upper prt of the suspension Nitrte nitrogen (NO3 - N) determintion Nitrte-nitrogen in the soil smple ws determined, using 0.5 M K2SO4. Ten grmmes of fresh soil ws shken in 30 ml of the extrctnt (0.5 M K2SO4) for 30 min. The soilextrctnt suspension ws filtered through Whtmn No. 42 filter pper to obtin cler solution. Nitrte in the cler solution ws determined by the colorimetric method. A 2ml liquot of the extrct ws pipetted into test tube nd 1 ml of slicylic cid solution ws dded. Slicylic cid solution ws prepred by dissolving 5 g slicylic cid in 95 ml concentrted sulphuric cid (Anderson nd Ingrm, 1998). The resulting solution ws llowed to stnd for 30 min, fter which 10 ml of 4.0 M Sodium hydroxide solution 28

43 ws dded nd mixed thoroughly. After 1 hour, when colour ws fully developed, the bsorbnce of the yellow colour ws red t wvelength of 410 nm on n electronic 21 D spectrophotometer. A stndrd series of 0, 2, 4, 6 nd 8 mg/l NO3 - -N ws prepred in 50 ml volumetric flsks from 50 mg/l NO3 - -N stock solution. The bsorbnce for ech stndrd ws then red on the spectrophotometer. A stndrd curve ws obtined by plotting grph of bsorbnce ginst stndrd concentrtions. The solution concentrtions for smple nd blnk were determined from the curve. The blnk vlue ws then subtrcted from the smple vlue to give vlue for the corrected concentrtion, C. Nitrte-nitrogen ws clculted s follows: NO3 - -N (mg/kg soil) = C V W where, C = corrected concentrtion (mg/l) V= extrct volume (ml) W = weight of smple (g) Ammonium nitrogen (NH4 + N) determintion The NH4 + -N ws determined from the sme extrct s NO3 - -N bove. A 2ml liquot of the extrct (filtrte) ws pipetted into test tube to which two different regents (RI nd RII) were dded. RI ws prepred by mixing three seprtely prepred solutions nmely: 4 % EDTA (5 ml), 0.05 g/ml Sodium nitroprussite (100 ml) nd 1.12 g/ml Sodium slicylte (50 ml). RII ws prepred by dissolving 0.2 g of Sodium dichlorocynte in 10 ml of distilled wter nd trnsferred to 200 ml flsk. The volume ws mde up to the mrk with buffer solution of M N2HPO4.12H2O (djusted 29

44 to ph The resulting solution ws llowed to stnd for 2 h fter the ddition of 3 ml nd 5 ml of RI nd RII, respectively. Working stndrds of 0, 5, 10, 15 nd 20 mg/l were prepred from 1 g/l NH4 + -N stock solution. The bsorbnce of the smple, blnk nd working stndrds were red on the spectrophotometer t wvelength of 660 nm. A grph of bsorbnce ginst stndrd concentrtions ws plotted. Solution concentrtions for the smple nd blnk were then determined. The blnk vlue ws subtrcted from the smple vlue to give vlue for corrected concentrtion, C. Ammonium-nitrogen ws clculted s follows: NH4 + -N (mg/kg soil) = C V W where C = corrected concentrtion (mg/l) V = finl digest or extrct volume (ml) W = weight of smple (g) Determintion of orgnic crbon / orgnic mtter Wet combustion method (Motsr nd Roy, 2008) ws used in the determintion of soil orgnic crbon nd orgnic mtter. One grmme of ir-dried soil ws weighed into 500-ml conicl flsk. A reference smple nd blnk were included. Ten millilitres of M Potssium dichromte (K2Cr2O7) solution ws dded to ech weighed soil smple nd two empty flsks (blnks), followed by the ddition of 20 ml concentrted Sulphuric cid (H2SO4). Ech smple ws swirled nd llowed to stnd for 30 min for the rection to complete. The rection mixtures were then diluted with 200 ml distilled wter nd 10 ml concentrted Orthophosphoric cid (H3PO4). Ten millilitres of Sodium fluoride (NF) solution nd 2 ml diphenylmine indictor were dded to the rection 30

45 nd titrted with stndrd 0.5M Ferrous sulphte (FeSO4) solution to brillint green colour. The two rections without soil smples (blnks) were run simultneously. The percentge of orgnic crbon (%OC) ws clculted s: 10(S T) S 100 Wt. of soil(g) 1.3 = 3 (S T) S 1. 3 (As 1 g of soil is used) Per cent OM ws clculted s: %OC x Where: S = millilitres of FeSO4 solution required for blnk; T = millilitres of FeSO4 solution required for soil smple; = weight of C (Thus, 1 ml M K2Cr2O7 = g C); 1.3 = Percentge vlue of orgnic crbon obtined; = Vn Bemmelen fctor Determintion of totl nitrogen Totl soil nitrogen ws determined by the Kjeldhl digestive nd distilltion protocol (Soils Lbortory Stff. Royl Tropicl Institute., 1984; Motsr nd Roy, 2008). One grmme of ir-dried soil smple ws weighed into Kjeldhl digestion flsk. To this, 0.7 g Copper sulphte, 1.5 g Potssium sulphte nd 30 ml of 0.05M Sulphuric cid were dded. The smple ws then digested for 3 h until cler digest ws obtined. The digest ws diluted with 50 ml distilled wter nd mixed by swirling until no more sediment dissolved nd llowed to cool nd trnsferred into distilling flsk. A 25 ml liquot of the solution ws trnsferred to the rection chmber nd 10 ml of 40 % NOH solution dded, followed by distilltion. The distillte ws collected in 2.0 % Boric cid nd ws titrted with 0.02 N HCl using Bromocresol green s indictor. A blnk 31

46 distilltion nd titrtion were lso crried out to tke cre of the trces of nitrogen in the regents s well s the wter used. The %N in the smple ws expressed s: Where %N = n = Concentrtion of HCl used in titrtion n ( b) 1.4 mcf w = Volume of HCl used in smple titrtion (ml) b = Volume of HCl used in blnk titrtion (ml) w = Weight of ir-dry soil smple (mg) mcf = moisture correction fctor ((100%+%moisture)/100) 1.4 = % (14 = tomic weight of N) Determintion of vilble phosphorus The vilble phosphorus ws extrcted with Bry s No.1 Extrctnt (0.03 M NH4F M HCl) s described by Bry nd Kurtz (1945). A 5 g soil smple ws weighed into 50-ml centrifuge tube nd 30 ml of Bry s Extrctnt No.1 dded. The mixture ws shken for 5 min on reciprocting shker nd centrifuged t 3000 rpm for 5 min. A 1ml liquot, 2 ml of the colouring regent (mmonium molybdte), 6ml distilled wter nd 1 ml L-Ascobic cid were pipetted into test tube nd uniformly mixed by shking. The solution ws llowed to stnd for 6 min for the blue colour to develop to its mximum. The bsorbnce ws mesured on spectronic 21D spectrophotometer t wvelength of 660 nm t medium sensitivity. Stndrd series of 0, 1, 2, 3, 4 nd 5 mgp/l were prepred from 20 mg/l phosphorus stock solution. 32

47 The stock solution ws prepred by dissolving g of pure KH2PO4 in 1 litre to obtin 50 μg P/ml stock solution. 10 ml of the stock solution ws diluted to 0.5 litres with distilled wter to obtin 1 μg P/ml solution. Avilble phosphorus ws clculted s follows: P (mg/kg soil) = ( b) mcf w where, = mg/l P in smple extrct b = mg/l P in blnk mcf = moisture correcting fctor 35 is volume of extrcting solution 15 is volume of finl solution w = smple weight in grmmes Determintion of exchngeble ctions Exchngeble bsic ctions (clcium, mgnesium, potssium nd sodium) in the soil were determined in 1.0 M mmonium cette extrct (Blck, 1986) nd the exchngeble cidity (hydrogen nd luminium) ws determined in 1.0 M KCl extrct (Pge et l., 1982). A 5 g soil smple ws weighed into leching tube nd leched with 100 ml buffered 1.0 M mmonium cette solution t ph 7. To nlyse for clcium nd mgnesium, 25 ml liquot of the extrct (lechte) ws trnsferred into n Erlenmeyer flsk, nd 1 ml portion of hydroxylmine 53 hydrochloride, 1 ml of 2.0 % potssium cynide, 1 ml of 2.0 % potssium ferrocynide, 10 ml ethnolmine buffer nd 0.2 ml Eriochrome Blck T solution were dded. The solution ws titrted with 0.01 M EDTA (ethylene diminetetrcetic cid) to pure turquoise blue colour. 33

48 Determintion of clcium only A 25 ml liquot of the 1.0 M mmonium cette extrct ws trnsferred into 250 ml Erlenmeyer flsk nd the volume mde up to 50 ml with distilled wter. Following this, 1 ml hydroxylmine, 1 ml of 2.0 % potssium cynide nd 1 ml of 2.0 % potssium ferrocynide solution were dded. After four minutes, 5 ml of 8.0 M potssium hydroxide solution nd sptul of murexide indictor were dded. The resultnt solution ws titrted with 0.01 M EDTA solution to pure blue colour. The concentrtions of clcium + mgnesium or clcium were clculted using the eqution: C + Mg (or C) (cmol(+)/kg soil) = 0.01 (V Vb) 1000 w Where, w = weight (g) of ir dried soil used V = ml of 0.01 M EDTA used in smple titrtion Vb = ml of 0.01 M EDTA used in blnk titrtion 0.01 = concentrtion of EDTA Determintion of exchngeble potssium nd sodium Potssium (K) nd sodium (N) in the lechte were determined by flme photometry. A stndrd series of potssium nd sodium were prepred by diluting both 1 g/l K nd N solutions seprtely to 100 mg/l. 25 ml portion of ech solution ws trnsferred into 250 ml volumetric flsk nd diluted to the 250 ml with distilled wter. Portions of 0, 5, 10, 15, 20 ml of the 100 mg/l stndrd solution were put into 200 ml volumetric flsks. One hundred millilitres of 1.0 M NH4OAc solution ws dded to ech flsk nd diluted to 200 ml with distilled wter. This resulted in stndrd series of 0, 2.5, 5.0, 7.5, 10 34

49 mg/l for K nd N. Potssium nd sodium were mesured directly in the lechte by flme photometry t wvelengths of nd nm, respectively. The concentrtions of Potssium nd Sodium were clculted using the following equtions: ( b) 250 mcf Exchngeble K (cmol(+)/kg soil) = w ( b) 250 mcf Exchngeble N (cmol(+)/kg soil) = w where, = mg/l K or N in the diluted smple percolte b = mg/l K or N in the diluted blnk percolte w = weight (g) of ir- dried soil smple mcf = moisture correcting fctor Determintion of effective ction exchnge cpcity (ECEC) This ws clculted by summtion of exchngeble bses (C 2+, Mg 2+, K + nd N + ) nd exchngeble cidity (Al 3+ nd H + ). 3.4 Dt nlysis The effects of the gro-ecologicl zones nd lndscpe (lnd use) on the soils physicochemicl properties nd nemtode ssemblge were observed by two-wy interction effects on the prmeters using Residul Mximum Likelihood (REML) Liner Mixed Models (VSN Interntionl, 2011). The Fixed Model: Agro-ecologicl zone*lndscpe, nd Rndom Model: Frm/Qudrt were used to run soil ph, orgnic C nd N, vilble nutrients nd exchngeble ctions. Mens were compred with stndrd error of difference t 5% probbility. 35

50 Nemtode community dt were run with the Residul Mximum Likelihood (REML) Liner Mixed Models with Fixed Model: Agro-ecologicl zone *Lndscpe, nd Rndom Model: Community. Prmeters run were Genus richness, Hills index (N2), Shnnon index, Simpson s index, combined mturity index, mturity index of plnt prsitic nemtodes, mturity index of free-living nemtodes nd fertility index. Mens were compred with stndrd error of difference t 5% probbility. The fixed models in the Residul Mximum Likelihood (REML) Liner Mixed Models represent the fctors tht would influence the differences observed whilst the Rndom Models represent repliction. Frmer socio-economic dt were presented s frequencies nd percentges in tbles nd grphs. 36

51 CHAPTER FOUR 4.0 RESULTS 4.1 Demogrphic profile of inhbitnts of the reserch res Ech gro-ecologicl zone is inhbited by multiplicity of tribes, some overlpping between zones. Ares smpled in the Semi-Deciduous Forest zone were extensively inhbited by the Ashntis nd Kwhus. These tribes cultivte wide vriety of crops; mjor of which re mize, cssv, cocoym, plntin, vegetbles nd csh crops such s coco nd oil plm. The Guine Svnnh zone is the driest of the three zones studied, with grsslnd vegettion nd clusters of drought resistnt trees such s bobb (Adnsoni spp) nd she (Vitellri prdox) trees. Mize, millet, sorghum, cowpe, soyben, ym nd vegetbles such s onion, pepper, nd tomto re mong the mjor crops cultivted by the Mmprusis who re the mjor inhbitnts of the selected communities. They lso own lrge herds of cttle nd smller ruminnts. Even though good number of frmers owned the lnd on which they frm, frm sizes were mostly two or less cres. Frmers were mostly mles cross ll zones. About 20 nd 6.7 % of respondents were femles in the Semi-Deciduous Forest nd Forest- Svnnh Trnsition zones, respectively. Among the Mmprusis, ll rndomly selected frmers were mles (Appendix 1). Mjority of respondents were over 31 yers of ge. In the Semi-Deciduous Forest zone, only 6.7 % of frmers were below the ge of 31 yers. In the Forest-Svnnh Trnsition nd Guine Svnnh, 13 nd 20 %, respectively, were below ge 31 yers (Appendix 1). The youth (below ge 40 yers) re ctively involved in crop cultivtion 37

52 mong ll tribes encountered. Among the Ashntis/Kwhus, 40 % of frmers were in the youth brcket. Among the Bonos nd Mmprusis, 60 nd 66.7 %, respectively, were within the youth brcket. The level of forml eduction mong frmers in ll zones ws generlly low. In the Semi-Deciduous Forest, Forest-Svnnh Trnsition nd Guine Svnnh zones, 53.3, 46.7 nd 36.7 % of frmers hd no forml eduction; 20, 40 nd 16.7 %, respectively, dropped out t the primry eduction level. The use of fmily lbour in number of frm opertions ws common, especilly mong the Mmprusis. Frmer household size vried mong zones with the Semi- Deciduous Forest zone hving the lest verge of bout 5 persons per household, followed by the Forest-Svnnh Trnsition zone with 7 nd the highest of 9 in the Guine Svnnh zone. Lngbinsi, one of the three selected communities in the Guine Svnnh zone, hd the highest vlue of bout 11 persons per frmer household (Fig. 4.1). 38

53 Kwso Nkwkw Nyinhin Amntin Nkornz Subinj Lngbinsi Nmnsi Mushio SDF FST GS NUMBER OF PERSONS (Semi- Deciduous Forest) (Forest- Svnnh Trnsition) (Guine Svnnh) AGRO-ECOLOGICAL ZONES AND SELECTED COMMUNITIES Figure 4.1: Averge frm household size of selected communities in the Semideciduous Forest, Forest-Svnnh nd Guine Svnnh gro-ecologicl zones. 4.2 Dominnt crop cultivtion prctices in the study res In the Semi-Deciduous Forest zone, 46.7 % of smpled mize nd tomto fields hd been continuously cropped for t lest three yers. Continuous cropping on the sme piece of lnd ws more pronounced in the Forest-Svnnh Trnsition nd Guine Svnnh with 66.7 nd 97.0 % smpled frms continuously cropped over the pst three or more yers (Tble 4.1). Lnd clering for new seson s cropping ws done by burning by some frmers. This prctice ws more common in the Semi-Deciduous Forest zone with 50 % of frmers prcticing it. About 40.0 nd 23.3 % of frmers in the Forest-Svnnh Trnsition nd Guine Svnnh zones, respectively, prcticed bush burning. About 37 % of the 39

54 frmers prcticed burning fter slshing or fter killing weeds with herbicide. The use of herbicide in the clering of lnd nd control of weed ws lso very common in ll three zones nd ws used in both mize nd tomto cultivtion. About 80.0, 83.3 nd 76.7 % of the frmers pplies herbicides in the Semi-Deciduous Forest, Forest- Svnnh Trnsition nd Guine Svnnh, respectively. The use of insecticide nd fungicide, however, ws totlly bsent in the cultivtion of mize. The use of minerl fertilizer ws highly ptronized in the cultivtion of both crops in ny of the three zones. Prctices such s the ppliction of frm yrd mnure nd compost, cover cropping nd intercropping with legumes were not common. No frmer prcticed cover cropping in ll the three zones. The use of herbicide is common mong surveyed frmers. In totl, 80% of frmers pply herbicide to their field (Tble 4.1). The rte of ppliction of liquid herbicide rnged from L/h verging 7.8 L/h cross ll the Zones. Tble 4.1 shows the percentge of tomto fields to which fungicide nd insecticide were pplied in the three zones. No mize field ws pplied with fungicides nd insecticides. All tomto frmers interviewed in Semi-Deciduous Forest hd pplied fungicides to their fields. About 40% of tomto fields in Forest- Svnnh Trnsition nd 53% in Guine Svnnh were pplied with fungicide. 40

55 Tble 4.1: Percentge distribution of frmers by selected cultivtion prctices in the Semi-Deciduous Forest, Forest-Svnnh Trnsition nd Guine Svnnh groecologicl zones. Prctice Semi- Deciduous Forest Forest- Svnnh Trnsition Guine Svnnh Mize Tomto Mize Tomto Mize Tomto Continuous cropping % % % % % % < 3yers > Insecticide ppliction Fungicide ppliction Semi- Deciduous Forest Forest- Svnnh Trnsition Guine Svnnh Bush burning Herbicide use Cover cropping Legume Intercropping Crop rottion Use of minerl fertilizer Use of frm yrd mnure Use of compost

56 4.3 Nutritionl sttus nd physicochemicl properties of soil smples from the study res Soil rection Mize sites in the Semi-Deciduous Forest zone hd n verge ph of 5.76, which ws not significntly different (P < 0.05) from tht of the undisturbed sites (5.76), but significntly higher (P < 0.05) thn wht ws recorded in tomto sites (5.27). In both the Forest-Svnnh Trnsition nd the Guine Svnnh, vritions observed were not significntly different (P < 0.05). (Fig 4.2A). The Semi-Deciduous Forest zone hd significntly lower verge ph of 5.13, thn the Forest-Svnnh Trnsition (5.822) nd Guine Svnnh zones (6.16) (Fig. 4.2 A) Orgnic mtter Orgnic mtter levels were highest in the Semi-Deciduous Forest zone, verging 1.53 %, followed by Forest-Svnnh Trnsition (1.25 %). Guine Svnnh recorded the lowest vlue of 0.85 %. Significnt difference in orgnic mtter content ws observed in the Semi-Deciduous Forest nd Guine Svnnh zones, compring the different lnd uses within ech zone (Fig. 4.2 B). In the Semi-Deciduous Forest zone, mize sites recorded n verge of 1.77 % OM content, significntly different (P < 0.05) from tomto sites (1.15 %) but not significntly different from tht of undisturbed sites (1.68 %). Vritions observed in the Forest-Svnnh Trnsition re no significntly different (P < 0.05). In the Guine Svnnh, however, mize sites recorded the highest vlue of Tomto sites recorded 0.93 % OM which is not significntly different (P < 0.05) from 0.52 % of the undisturbed sites (Fig. 4.2 B). 42

57 4.3.3 Nitrogen Totl nitrogen (%N) ws highest in the Semi-Deciduous Forest zone nd lowest in the Forest-Svnnh Trnsition zone. The Guine Svnnh zone hd significntly lower (P < 0.05) totl nitrogen thn the Semi-Deciduous Forest zone, but higher thn tht of the Forest-Svnnh Trnsition zone (Fig. 4.2 C). Mize lndscpes hd the highest totl nitrogen in the Semi-Deciduous Forest zone, but hd lest %N in the Guine Svnnh zone. In the Forest-Svnnh Trnsition, %N in mize nd tomto sites were identicl but were both lower thn %N of undisturbed sites. Avilble nitrogen (NO3 - +NH4 + ) levels, however, were identicl mong the zones nd lndscpes of the Semi- Deciduous Forest zone but highest in undisturbed sites of both Forest-Svnnh Trnsition nd Guine Svnnh zones Avilble P, exchngeble K, C, Mg nd N Guine Svnnh hd the highest levels of vilble Phosporus nd exchngeble Potssium, but hd the lest of exchngeble Mgnesium s compred to the Semi- Deciduous Forest nd the Forest-Svnnh Trnsition which were identicl. Avilble Phosphorus levels vried mong lndscpes within gro-ecologicl zones (Fig. 4.3 B). Potssium vlues were not significntly different (P < 0.05) mong lndscpes in both Semi-Deciduous Forest nd Forest-Svnnh Trnsition zones. In the Guine Svnnh, undisturbed sites hd the highest level of exchngeble K. Sodium levels were identicl cross ll three gro-ecologicl zones nd lndscpes within Forest- Svnnh Trnsition nd Guine Svnnh zones (Fig. 4.3 C). In the Semi-Deciduous Forest, tomto sites hd higher exchngeble N thn undisturbed sites but identicl to mize; mize sites, however, were similr to tomto nd undisturbed lndscpes in the Forest-Svnnh Trnsition nd Guine Svnnh 43

58 zones. Clcium levels were lowest in the Guine Svnnh zone nd identicl mong its lndscpes, whilst Semi-Deciduous Forest nd Guine Svnnh zones hd identicl levels with their lndscpes showing vrying differences mong their lndscpes. Guine Svnnh hd lest Mg with its lndscpes showing no significnt differences. In the Semi-Deciduous Forest nd Forest-Svnnh Trnsition Mg levels were significntly different mong their lndscpes (Fig 4.4 A) Al, H nd Effective ction exchnge cpcity (ECEC) (cmol(+)/kg) The Guine Svnnh hd the highest level of Al + H with its mize lndscpe recording the lest level. Lndscpes within the Semi-Deciduous Forest nd Forest- Svnnh Trnsition zones showed no significnt differences. ECEC, summtion of (K, C, Mg, N, Al nd H in cmol(+)/kg) showed vrious vritions between nd within the gro-ecologicl zones. The Forest-Svnnh Trnsition zone hd the highest verge ECEC of cmol(+)/kg. The verge ECEC of the Semi-Deciduous Forest nd Guine Svnnh zones were 6.91 nd 6.29 cmol(+)/kg, respectively, but re not significntly different (P < 0.05) (Fig 4.5). 44

59 Mize Tomto Nturl Mize Tomto Nturl Mize Tomto Nturl Forest Trnsition Svnnh Totl nitrogen (%) Orgnic mtter(%) ph 6 5 b b b A b c b b b c 1 b 0 B b b b b b c b c C 0 Semideciduous Forest. Forest- Svnnh Trnsition. Guine Svnnh. Agroecologicl zones Agro-ecologicl zones nd lnd uses Figure 4.2: A= Soil ph, B = OM (%) nd C = orgnic nitrogen (%) of Mize, Tomto nd Undisturbed sites in the Semi-Deciduous Forest, Forest-Svnnh Trnsition nd Guine Svnnh gro-ecologicl zones. Dt represent nlysis of 132 smples in ech gro-ecologicl zone. Brs with different letters within n gro-ecologicl zone re sttisticlly different (P < 0.05) 45

60 Mize Tomto Nturl Mize Tomto Nturl Mize Tomto Nturl Forest Trnsition Svnnh K (cmol (+) /kg) P (mg/kg) NO NH 4 + (mg/kg) b b b b A b b b b b b b b 2 0 B b b b b C 0 Semideciduous Forest. Forest- Svnnh Trnsition. Guine Svnnh. Agroecologicl zones Agro ecologicl zones nd lndscpes Figure 4.3: A = Soil vilble nitrogen (NO3 - + NH4 + in mg/kg), B = P (mg/kg) nd C = K(cmol(+)/kg) of Mize, Tomto nd Undisturbed lndscpes in the Semi-Deciduous Forest, Forest-Svnnh Trnsition nd Guine Svnnh gro-ecologicl zones. Dt represent nlysis of 132 smples in ech gro-ecologicl zone. Brs with different letters within n gro-ecologicl zone re sttisticlly different t P =

61 Mize Tomto Nturl Mize Tomto Nturl Mize Tomto Nturl Forest Trnsition Svnnh N (mg/kg) C (cmol (+) /kg) Mg (cmol (+) /kg) 2.5 b b b b c b A b b b c b b b B b b C Semideciduous Forest. Forest- Svnnh Trnsition. Guine Svnnh. Agroecologicl zones Agro-ecologicl zones nd lndscpes Figure 4.4: A = Soil C (cmol(+)/kg), B = Mg (cmol(+)/kg) nd C = N (mg/kg) of Mize, Tomto nd Undisturbed lndscpes in the Semi-Deciduous Forest, Forest- Svnnh Trnsition nd Guine Svnnh gro-ecologicl zones. Dt represent nlysis of 132 smples in ech gro-ecologicl zone. Brs with different letters within n gro-ecologicl zone re sttisticlly different t P =

62 Mize Tomto Nturl Mize Tomto Nturl Mize Tomto Nturl Forest Trnsition Svnnh ECEC (cmol/kg) b b b c b b 2 0 Semideciduous Forest. Forest- Svnnh Trnsition. Guine Svnnh. Agroecologicl zones Agro-ecologicl zones nd lndscpes Figure 4.5: Effective ction exchnge cpcity in cmol(+)/kg of Mize, Tomto nd Undisturbed lndscpes in the Semi-Deciduous Forest, Forest-Svnnh Trnsition nd Guine Svnnh gro-ecologicl zones. Dt represent nlysis of 132 smples in ech gro-ecologicl zone. Brs with different letters within n gro-ecologicl zone re sttisticlly different t P =

63 4.4 Nemtode community nlysis Nemtode community nlysis ws done to revel nemtode diversity, ecologicl disturbnce nd soil food web nd nutrient cycling potentil Nemtode diversity A totl of 61 gener of nemtodes were identified; 50, 51 nd 49 gener were identified in the Semi-Deciduous Forest, Forest-Svnnh Trnsition nd Guine Svnnh grologicl zones, respectively. Appendices 2, 3 nd 5 list nemtodes gener identified in the vrious lndscpes of the three gro-ecologicl zones under study. Mjority of the identified gener, in undisturbed lndscpes of ll three gro-ecologicl zones, were bcterivorous (Appendices 3,4,5). The reltive bundnce of the nemtode gener vried cross gro-ecologicl zones with some gener totlly bsent in some the zones. Plnt prsitic gener; Aglenchus, Anguin, Criconem, Criconemoides, Helicotylenchus Hoplolimus, Moloidogyne, Prtylenchus, Rotylenchus, Tylenchorhynchus, Prtrichodorus nd Longidorus were present in ll the three groecologicl zones. Mlenchus ws bsent in the Guine Svnnh zone. Tylenchus, Rdopholus, Globoder, Hirschmenniell, Rotylenchulus nd Xiphenem were bsent in the Forest Svnnh Trnsition zone. With bcteri-feeding nemtodes, the gener Pngrolimus, Protorhbditis, Acrobeles, Chiloplcus, Eucephlobus, Heterocephlobus, Plectus, Pseudcrobeles, Zeldi, Wilsonem nd Prismtolimus were present in ll the three gro-ecologicl zones. Odontophrynx ws bsent in the Forest-Svnnh Trnsition zone. Ethmolimus ws bsent in the Guine Svnnh zone. Acrolobus, Microlimus nd Mesorhbditis were present only in the Forest-Svnnh Trnsition. 49

64 Fungivorous gener, Aphelenchoides, Aphelenchus, Ditylenchus nd Filenchus were present in ll the three gro-ecologicl zones. Mononchus, predtor genus, ws identified only in the Semi-Deciduous Forest nd Guine Svnnh gro-ecologicl zones. Omnivorous gener, Dorylimus, Tylenchodorus, Nygolimus nd Prodorylimus were identified in ll the zones. The Semi-Deciduous Forest gro-ecologicl zone recorded n verge Genus richness (N0) of 18.53, nd for mize, tomto nd undisturbed lndscpes, respectively. Averge genus richness for mize, tomto nd undisturbed lndscpes in the Forest-Svnnh Trnsition zone were 17.53, nd respectively; nd 12.93, 10.53, for mize, tomto nd undisturbed lndscpes in the Guine Svnnh zone. Undisturbed lndscpes in ech gro-ecologicl recorded higher genus richness, compred to mize nd tomto lndscpes in the respective zones. Mize nd tomto lndscpes of the Guine Svnnh hd the lowest genus richness (Fig 4.6 A). Hills index (N2), which is mesure of the number of very dominnt tx, ws lest in tomto lndscpes of the Guine Svnnh zone; however ws not significntly different (P < 0.05) from tht of undisturbed sites in the Guine Svnnh zone. In the Semi-deciduous Forest zone, ll three lndscpes were not significntly different (p < 5). Undisturbed sites in the Forest-Svnnh Trnsition zone hd significntly higher Hills index (N2) thn tomto lndscpes but not significntly different from tht of mize lndscpes (Fig 4.6 B). Shnnon index mesures nemtode diversity by focussing on rre nemtode tx. The more rre nemtodes present, the higher the Shnnon index. In the Semi-deciduous 50

65 Forest zone, mize, tomto nd undisturbed sites recorded 2.640, nd respectively, which were not significntly (P < 0.05) different from ech other. Some significnt (P < 0.05) vritions were observed in both Forest-Svnnh Trnsition nd Guine Svnnh zones with undisturbed sites recording highest vlues of nd 2.520, respectively. In the Guine Svnnh zone, however, Shnnon index of mize (2.423) ws not significntly (P < 0.05) different from tht of the undisturbed sites. Simpson index, unlike Shnnon index, is sensitive to common nemtode tx in mesuring nemtode diversity. No significnt (P < 0.05) vritions were observed mong the vrious lnd uses in the Semi-deciduous Forest zone: 0.083, nd for mize, tomto nd undisturbed respectively. Tomto fields recorded the highest Simpson s index; 0.11 nd 0.15, in the Forest-Svnnh Trnsition nd Guine Svnnh zones, respectively, (Fig 4.6 D) Ecologicl disturbnce Mturity index mesures the level of disturbnce of the soil ecosystem with lower vlues indicting more disturbnce. Combined mturity index (ΣMI) tkes into considertion ll nemtode trophic groups present soil smple. Undisturbed sites in ll three zones hd the highest combined mturity index: 1.57, 1.69 nd 1.45 for the Semi-Deciduous Forest, Forest-Svnnh Trnsition nd Guine Svnnh zones respectively. (Fig4.7A). The most disturbed soils in terms of combined mturity index were mize nd tomto sites in the Semi-deciduous Forest (1.13 nd 1.01 respectively) nd Guine Svnnh zones (0.94 nd 1.16 respectively). Vritions in mturity index of plnt prsitic nemtodes (PPI) differed from wht ws observed in combined mturity index. In the Semi-deciduous Forest zone, mize recorded the lest vlue of which is significntly different (P < 0.05) nd 51

66 3.11 of tomto nd undisturbed sites. Even though mize sites in the Forest-Svnnh hd the lest vlue of 2.365, this ws not significntly different from tht of tomto (2.705) nd undisturbed (2.624) sites. Significnt difference ws lso not observed mong the vrious lnd uses in the Guine Svnnh zone. (Fig4.7B). The vritions observed in mturity index of free-living nemtodes were slightly similr to wht ws observed in the combined mturity index. The most disturbed free living nemtode (lest mturity index of free-living nemtodes) ws in mize (1.728) sites of the Guine Svnnh zone. The lest disturbed free-living popultion ws observed in undisturbed lndscpes of the Forest-Svnnh Trnsition zone (2.241), even though this is not significntly different from tomto (2.108) nd mize (2.087) sites Soil food web The reltionship between Enrichment Index ( mesure of opportunistic bcterivorous nd fungivorous nemtodes), nd the Structure Index (indictor of food web stte ffected by stress or disturbnce) ws used for grphic representtion (Fig 4.9) which describes the soil community profile in four qudrnts ccording to Ferris et l. (2001): Qudrt A= enriched but unstructured, Qudrt B = enriched nd structured, Qudrt C = resource-limited nd structured, nd Qudrt D = resource-depleted with miniml structure. The results cross lndscpes nd gro-ecologicl zones were concentrted in Qudrt A nd Qudrts D. Soil food webs in Semi-Deciduous Forest, in generl, hd depleted resource with miniml structure. In Forest-Svnnh Trnsition, nerly ll soils from mize lndscpe hd highly enriched but unstructured food web with tht of undisturbed lndscpes being resource-depleted nd miniml structure. Mjority of 52

67 tomto lndscpes in the Forest-Svnnh Trnsition lso hd food webs of miniml structure with depleted resource. In the Guine Svnnh, tomto lndscpes hd slightly enriched nd miniml structured soil food web. 53

68 Mize Tomto Nturl Mize Tomto Nturl Mize Tomto Nturl D H' N2 N A B C D 0.05 Semi-Deciduous Forest Forest-Svnnh Trnsition Guine Svnnh Figure 4.6: A= Genus richness B = Hills Index (N2), C = Shnnon Index (H ), D= Simpson s Index (D) of Mize, Tomto nd Undisturbed lndscpes in the SEMI- Deciduous Forest, Forest-Svnnh Trnsition nd Guine Svnnh gro-ecologicl zones. 54

69 Mize Tomto Nturl Mize Tomto Nturl Mize Tomto Nturl MI PPI ΣMI A B C 1.6 Semi-Deciduous Forest Forest-Svnnh Trnsition Guine Svnnh Figure 4.7: A= Combined Mturity Index (ΣMI) B = Mturity Index of Plnt Prsitic Nemtodes (PPI), C = Mturity Index of Free-living Nemtodes (MI) of Mize, Tomto nd Undisturbed lndscpes in the Semi-Deciduous Forest, Forest-Svnnh Trnsition nd Guine Svnnh gro-ecologicl zones. Dt represent nlysis of 33 smples in ech gro-ecologicl zone. Error brs represent stndrd error of difference (P < 0.05). 55

70 Enrichment Index Enrichment Index Enrichment Index 100 A 50 Mize Tomto Nturl Qudrt A Qudrt B B 50 Qudrt D Qudrt C C Structure Index Figure 4.8: The soil food web stte of mize, tomto nd undisturbed lndscpes in Semi-Deciduous Forest (A), Forest-Svnnh Trnsition (B) nd Guine Svnnh (C). 56

71 CHAPTER FIVE 5.0 DISCUSSION 5.1 Demogrphics Ninety-one percent of the heds of frms surveyed were mles. Even though women, nd, sometimes, children, were encountered ctively working on the frms, men re generlly regrded hed of the household, hence hed nd owner of the frmlnd. Despite the importnt role women ply in griculture, they hve much more limited ccess to lnd nd griculturl extension thn their mle counterprts (Duncn, 2004). This phenomenon is more prevlent in the northern prts of Ghn. IFAD s (1998) evlution of the Upper Est Region of Ghn (Guine Svnnh zone) estblished tht even though women supply up to 80% of the lbour in frm ctivities such s hrvesting, storing, processing nd mrketing of frm produce, they hve limited ccess to nd control of lnd. At best, womn cn expect to obtin temporry use of plot of lnd from her husbnd, if the ltter feels he cn spre the womn s lbour (IFAD, 1998). The study confirmed this, since ll the 33 frmers rndomly interviewed in Guine Svnnh zone were mles (Tble 4.1). Agriculture offers over 10 million jobs in Ghn (Oppong-Anne, 2006). Sixty percent nd 67 % of respondents in the Forest-Svnnh Trnsition nd Guine Svnnh, respectively, were below the ge of 40 whilst 40% in the Semi-Deciduous Forest zone were below the ge of 40 (Tble 4.1). This survey reveled tht the youth re ctively involved in griculture with respect to mize nd tomto cultivtion in the three groecologicl zones. However, mjority of them hve no form of forml eduction. In Ghn, frming is considered s work for the poor nd uneducted. This ws clerly evident in the distribution of the frmers by level eductionl cquired (Appendix 1). 57

72 In the Guine Svnnh zone, for exmple, none of the frmers interviewed ttined tertiry eduction. Some level of eduction my be necessry for frmers to understnd nd implement, without supervision, some types of strtegies. Some bsic skills like record keeping, crop spcing, ppliction of gro inputs t recommended rtes, observing withdrwl periods of biocides, composting, re enhnced by eduction Access to lnd nd cultivtion prctices The type of cultivtion prctice chosen by n individul lrgely depends on his/her culture, level of eduction, vilble technology nd income level. Mny smll holder frmers receive wek suport from their government with regrd to productive technologies, extension support, helth nd eduction, which limits the blity of smll holder frmers to grdute from porvety through griculturl productive growth (Jyne et l., 2005). Most of the frmers, interviewed, reveled tht the Ministry of Food nd Agriculture hve not been consistent in providing them with improved cropping technologies through their extension service. Sttistics, Reserch nd Informtion Directorte (SRID) of MoFA (2010) reported tht bout 90 % of frm holdings in Ghn re less thn 2 hectres. Access to lnd plys n importnt role in sustinble griculture; frmers with limted lnd re tend to continously cultivte the sme prcel of lnd for prolonged number of yers. Access to lnd my lso influence the re of lnd t the disposl of frmers; the mjority of frmers interviewed hd frms of not more tht n cre (0.4 h) (Appendix 1). Owning lnd, however, does not gurntee frmers bility to cultivte lrge res of lnd s other fctors such s technology nd funding re necessry. Out of the 65 frmers who owned the frmlnd, 59 of them cultivted less thn 3 cres of lnd. 58

73 The survey discovered tht even though mjority of frmers continuously cultivted their lnds for over 9 yers in the Semi-Deciduous Forest nd Forest-Svnnh Trnsition zones (Tble 4.1), their cultivtion prctices, however, were not directed towrds mintining good soil helth. Lnd clering by burning which ws common prctice cross ll the three gro-ecologicl zones, destroys soil biot which in turn influences the nutrient cycling bility of the soil ecosystem in negtive wy. Different griculturl prctices ffect soil biot in different wys nd the response my be positive or negtive (FAO, 2014). Cultivtion prctices, such s tillge, crop rottion, fertilizer nd biocide ppliction, influence soil biot popultion, diversity nd functions (Gupt et l., 2014). Once forest is open up for cultivtion, the soil grdully loses orgnic mtter nd the fertility of the soil declines s lnd is left bre nd exposed to erosion of soil nd nutrients (IIRR nd ACT, 2005). The debris from clering of forest for cultivtion is usully burnt to mke wy for cultivtion. Once the soil orgnic mtter content begins to decline without dequte replenishment, the soil grdully losses its fertility nd its bility to support the initil soil popultion. The rte of fertility loss nd orgnic mtter loss my increse when frmers mke no intentionl effort to replenish the soil s reservoir of orgnic mtter. Addition of compost, crop rottion, cover cropping nd ddition of frm yrd mnure re mong prctices tht improve orgnic mtter build up nd soil fertility replenishment, but were very rrely prcticed by the frmers. The fst physicl, nutritionl nd biologicl deteriortion of soils in Afric nd the consequent declines in griculture productivity re s result of inpproprite soil preprtion nd tillge methods dopted by most frmers (FAO, 2000). 59

74 5.2 Types nd levels of nutritionl nd physicochemicl degrdtion The observed vritions in soil orgnic crbon content mong gro-ecologicl zones cn be ttributed to the differences in vegettion, mount of nnul rinfll nd humn ctivities. Even though the Guine Svnnh hs vegettion which promotes orgnic mtter build-up, levels were comprtively low. The perennil problem of bush fires in Northern Ghn during the long dry seson (Grib, 2011) nd high tempertures re mjor fctors which my explin the low levels of soil orgnic mtter, especilly in undisturbed sites which re t the mercy of bush fires in the Guine Svnnh zone. Effect of crop cultivtion on soil orgnic mtter content vried mong zones. The reltively higher level of percent orgnic mtter in mize lndscpes in the Guine Svnnh zone (Fig 4.2B) my be ttributed to the superior bility of mize (C4 plnts) to ccumulte dry mtter (Ehlers nd Goss, 2003) but these levels were fr below those of the Semi-Deciduous Forest zones s, most mize fields in the Semi-Deciduous Forest zone were mostly newly opened forests. In the Forest-Svnnh Trnsition, even though sttisticl differences were not detected, cultivtion reduced soil orgnic mtter content. MoFA (1998) suggested the regulr incorportion of mnure into soils in the Svnnh zones to improve their soil orgnic mtter percentge. This pproch is fesible since the Guine Svnnh zone hs the mjor livestock production regions of Ghn (Oppong-Anne, 2006). Studies in Keny by Kpkiyi et l. (1999) reveled tht; ddition of high rte of minerl fertilizers nd mnure nd retention of mize stover, individully, did not reverse decline of soil orgnic mtter resulting from continuous cultivtion, but combintion of the mendments hlved the loss of soil orgnic mtter. However, they concluded tht stover nd mnure re counterblnce becuse stover is mjor component of ruminnt diet. Oppong-Anne (2006) confirms tht most livestock 60

75 frmers prctice supplementry feeding, using crop residues, in the dry seson. Some households use crop residues such s mize nd millet stlks for lternte purposes such s fuel nd thtching of roof. Smllholder frmers effort lone, if ny, in improving soil orgnic levels in cultivted soils, is indequte. Their ctivities rther worsen the deprived levels of soil orgnic mtter. In order to improve the level soil orgnic mtter content, the study suggests n integrtive nd interdisciplinry pproch. For instnce, Ghn Institute of Engineers (2013) estimtes tht 3 million tons of solid wste is generted every yer in Ghn; most of which is generted in the urbn res. The wste cn be recycled into orgnic fertilizer nd other products. Orgnic fertilizer from such setup is expected to be reltively cheper thn imported minerl fertilizer. Once frmers re educted by the Ministry of Food nd Agriculture on the importnce of supplementing minerl fertilizer with the orgnic type, frmers my ptronize the low priced but useful orgnic fertilizer which would enhnce soil orgnic mtter percentge nd nutrient levels in cultivted soils. Results from this reserch, ccording to soil nutrient rtings by Lognthn (1987) (Appendix 5), indicte tht both cultivted nd undisturbed lndscpes hve low levels of plnt nutrients such s %N, K, P, C nd Mg in ll three gro-ecologicl zones. Totl nitrogen levels of mize lndscpes in the Semi-Deciduous Forest zones were of moderte quntities. In the Forest-Svnnh Trnsition nd Guine Svnnh zones, cultivtion of mize nd tomto hd further reduced %N in the soils. The introduction of country-wide price subsidy on some types of minerl fertilizers by the government of Ghn in 2008, in ttempt to mitigte the effect of rising food 61

76 prices (Bnful, 2009), my hve encourged more frmers to use fertilizers but still below the recommended rtes of ppliction (Rgs et l., 2013). Frmers, therefore, continue to remove nutrients from the soil when they hrvest their crops but do not replce these nutrients with the right rte of minerl fertilizers. This would men tht frmers yield will continue to dwindle over time nd likely to mke the frm less productive nd profitble. In the wke of climte chnge nd its impcts on griculture, the plight of smllholder frmers my worsen. 5.3 Level of biologicl degrdtion Nemtode community diversity Every soil nemtode tx is specilised in wht they feed on. There re bcteri-feeders, fungi-feeders, predtors, omnivores nd herbivores (plnt prsites). For this reson, nemtodes ply centrl role in the soil food web (Neher, 2001). The diversity in nemtode community reflects the soil ecosystem sttus. The reduced nemtode richness (indicted by the number of gener) in mize nd tomto lndscpes, compred to the undisturbed lndscpes in their respective groecologicl zones, indictes the interference in nemtode community by crop cultivtion. Nemtode diversity (N0, N2, H nd D) vried mong the vrious lndscpes in the Forest-Svnnh Trnsition nd Guine Svnnh zones, but identicl mong lndscpes of the Semi-Deciduous Forest zone. Most cultivted soils of the Semi- Deciduous Forest were freshly opened forests, hence, even though diversity seems to be slightly higher in undisturbed soils, vlues were not sttisticlly different from those of mize nd tomto lndscpes. The reltively hrsh (dry climte nd low orgnic) soil condition nd prolonged lnd cultivtion could explin the lower nemtode diversity in the Guine Svnnh. 62

77 5.3.2 Ecologicl disturbnce Cultivtion prctices such s tillge, fertiliztion, irrigtion nd pesticide ppliction cuse disturbnce of soil ecosystem; if soil ecosystem receives nutrient input, for exmple, opportunistic bcterivorous nd fungivorous nemtodes respond rpidly to the corresponding increse in their resources (Villenve et l., 2013; Bongers et l., 1997). Mturity index is mesure of disturbnce of the soil nemtode community with smller vlues being indictive of more disturbed environment (Neher nd Drby, 2006). The ddition of minerl fertilizer nd biocides such s herbicides nd fungicides to the soil is common in ll three gro-ecologicl zones nd this is reflective in the low vlues of combined mturity index (ΣMI) in mize nd tomto lndscpes, indicting disturbnce of the soil ecosystem by crop cultivtion Soil food web The Enrichment Index nd the Structure Index, both bsed on the indictor importnce of functionl guilds of nemtodes, re descriptors of food web condition. Soil food web conditions vried with lndscpes nd gro-ecologicl zones, but were generlly of miniml structure which is indictive of low prevlence of higher trophic level nemtodes which my be consequence of environmentl perturbtion or of griculturl prctices. (Ferris et l., 2001; Neher nd Drby, 2006). In the semideciduous forest, soil food web generlly re of miniml structure nd not very enriched. Food web of Tomto lndscpes of the forest-svnnh trnsition were concentrted t the proximl end of the structure trjectory, hence, re considered bsl nd my indicte stressed environment ccording to Ferris et l (2001). Overll, the study shows tht the soils hve structurl deficits which is consistent with the soil physiochemicl dt. 63

78 CHAPTER SIX 6.0 CONCLUSION AND RECOMMENDATION This study confirms the hypothesis of this reserch tht cultivtion prctices re not directed towrds the mintennce of good soil helth. It ws lso discovered tht soils of the study res re inherently poor in terms of plnt nutrients nd frgile in terms of soil food web condition, even in undisturbed soils. The wrm tropicl climtic nd unsustinble cultivtion prctices impede the ccumultion of orgnic mtter (OM) which serves s the power house for soil ecosystem nd source of plnt nutrient. The severity of low nutrients in the three gro-ecologicl zones, especilly in the Guine Svnnh zone, requires the ppliction of soil mendments in right quntities in ddition to strtegic mngement prctices to enhnce OM build-up nd nutrient levels in the soil. The level of nutritionl degrdtion nd soil ecosystem frgility vrition mong groecologicl zones nd lndscpes suggest tht the one-size-fits ll pproch of solving nutrient nd biologicl degrdtion is not the wy to go. However, enhncement of OM levels of soils might, in ll cses, be necessry for improving nutrient sttus nd soil food web conditions. The study recommends n interdisciplinry nd collbortive reserch in developing loclly pplicble technologies which will enhnce the productivity of frmers but not t the expense soil helth. The study noticed the widespred use of cell phone mong frmers. This could be useful tool for communicting informtion such s wether forecst, commodity prices s well s tilored cultivtion technologies directly to frmers. This could be wy to bridge the gp between frmers nd the Extension Services of Ministry of Food nd Agriculture. The study, therefore, recommends tht the Ministry of Food nd 64

79 Agriculture should tke dvntge of telecommuniction technologies in trnsferring tilored cultivtion technologies to frmers. The quntum of solid wste generted in Ghn especilly t the urbn centres lso offers n opportunity for the mnufcture of orgnic fertilizer which cn improve soil helth considerbly. The study recommends tht Government of Ghn should develop policies tht would set up recycling plnts tht would produce orgnic fertilizer from orgnic wstes. Orgnic fertilizer produced in this mnner cn then be incorported into the ntionl fertilizer subsidy progrmme which, t the long run, would improve the level of orgnic mtter content of cultivted soils. 65

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87 APPENDICES Appendix 1: Demogrphic distribution of respondents in the vrious communities selected within the Semi-Deciduous Forest, Forest-Svnnh Trnsition nd Guine Svnnh gro-ecologicl zones. Semi-Deciduous Forest zone Forest-Svnnh Trnsition zone Guine Svnnh zone No. of respondents Totl % No. of respondents Totl % No. of respondents Totl % Kwso Nkwkw Nyinhin Amntin Nkornz Subinj Lngbinsi Nmnsi Mushio Sex Femle Mle Age < Eduction None Islmic Primry Secondry Tertiry Lndownership Owned Lesed Shre Gin Frm Size (c) >

88 Appendix 2: Nemtodes identified in mize, tomto, nd undisturbed lndscpes of the Semi-Deciduous Forest zone Trophic Group Genus Cp-vlue Mize Tomto Undisturbed % % % Plnt prsitic Aglenchus Anguin Mlenchus Tylenchus Rdopholus Criconem Criconemoides Globoder Helicotylenchus Hirschmenniell Hoplolimus Meloidogyne (J2) Prtylenchus Rotylenchulus Rotylenchus Tylenchorhynchus Prtrichodorus Longidorus Xiphinem Bcterivores Pngrolimus Protorhbditis Acrobeles Acrobeloides Chiloplcus Eucephlobus Heterocephlobus Monhysteride Plectus Pseudcrobeles Zeldi Wilsonem Prismtolimus Odontophrynx Ethmolimus Fungivores Aphelenchoides Aphelenchus Ditylenchus Filenchus Diphtherophoride Predtors Mononchus Omnivores Dorylimus Eudorylimus Thornenem Tylenchodorus Aporcelimellus Aporcelimus Discolimide Nygolimus Prodorylimus

89 Appendix 3: Nemtodes identified in mize, tomto, nd undisturbed lndscpes of the Forest-Svnnh Trnsition zone Trophic Group Genus Cp-vlue Mize Tomto Undisturbed % % % Plnt prsitic Aglenchus Anguin Mlenchus Prtylenchus Criconem Criconemoides Helicotylenchus Hoplolimus Meloidogyne (J2) Prtylenchus Rotylenchus Tylenchorhynchus Prtrichodorus Longidorus Bcterivores Pngrolimus Protorhbditis Acrobeles Acrobeloides Cephlobus Cervidellus Chiloplcus Acrolobus Eucephlobus Heterocephlobus Monhysteride Plectus Pseudcrobeles Microlimus Zeldi Wilsonem Prismtolimus Mesorhbditis Ethmolimus Fungivores Aphelenchoides Aphelenchus Ditylenchus Filenchus Diphtherophoride Omnivores Dorylimus Eudorylimus Microdorylimu Thornenem Tylenchodorus Tylencholimus Aporcelimellus Aporcelimus Discolimoides Discolimide Discolimus Nygolimus Prodorylimus

90 Appendix 4: Nemtodes identified in mize, tomto, nd undisturbed lndscpes of the Guine Svnnh zone Trophic Group Genus Cp-vlue Mize Tomto Undisturbed % % % Plnt prsitic Aglenchus Anguin Tylenchus Rdopholus Criconem Criconemoides Globoder Helicotylenchus Hirschmenniell Hoplolimus Meloidogyne (J2) Prtylenchus Rotylenchulus Rotylenchus Tylenchorhynchus Prtrichodorus Trichodorus Longidorus Xiphinem Bcterivores Pngrolimus Protorhbditis Acrobeles Acrobeloides Chiloplcus Eucephlobus Heterocephlobus Monhysteride Plectus Pseudcrobeles Zeldi Wilsonem Prismtolimus Odontophrynx* Fungivores Aphelenchoides Aphelenchus Ditylenchus Filenchus Predtors Mononchus Omnivores Dorylimus Tylenchodorus Nygolimus Prodorylimus

91 Appendix 5: Rtings of soil nutrient in griculturl soils (Logthn, 1987). Very low Low Moderte High Very High N% < < 0.03 P(ppm) < < 30 K (meq/100g) < < 1.0 C (meq/100g) < < 20 Mg (meq/100g) < <

92 Appendix 6: Nemtode gener imge gllery from the study Criconemoides Eucephlobus Heterocephlobus Aphelenchoides Helicotylenchus Mononchus 78