Use of green manure legume cover crops in smallholder maize production systems in Limpopo province, South Africa

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1 Africn Journl of Soil Science Vol. 2 (3), pp , September, Avilble online t Interntionl Scholrs Journls Full Length Reserch Pper Use of green mnure legume cover crops in smllholder mize production systems in Limpopo province, South Afric Kiser Cedric Deprtment of plnt nd crop science, Fculty of Science nd Agriculture, University of Fort Hre, Est London, Estern Cpe, South Afric. Emil: Kiser62@yhoo.com Accepted 07 August, 2014 Much of the smllholder frming sector in Limpopo province of South Afric is locted on infertile degrded soils, with nitrogen being one of the predominntly deficient nutrient. The use of green mnure legume cover crops in combintion with Nitrogen (N) fertilizers is one option for improving N inputs into such frming systems. The objectives of this study were to (1) screen number of green mnure legume cover crop species, mucun (Mucun pruriens); sunhemp (Crotlri junce), lb- lb (Lblb purpureus); cowpe (Vign unguicult) nd butterfly pe (Clitori ternte) in order to determine their suitbility for the region nd (2) to determine the effect of the green mnure nd nitrogen fertilizer on mize yield. The legumes were screened during the winter sesons of 2005 nd 2006 nd the summer sesons of nd The best-bet legumes (mucun, sunhemp nd lb-lb) were then evluted to determine their effect on mize grin yield with or without nitrogen fertilizer. The tretments imposed were mucun, sunhemp, lb-lb, nd control with (75 kg N h -1 ) or without (0 kg N h -1 ) N fertilizer. Mize ws hrvested t mturity to determine the grin yield. In the screening trils, legume biomss yield rnged between 41 to 1,672 kg h -1, while the N content rnged between 2 to 58 kg N h -1 in the winter trils. In the summer trils, biomss yield rnged from 899 to 13,586 kg h -1, while the N content rnged between 27 to 302 kg N h -1. Mize yield rnged between 4.0 to 6.4 tons h -1 in the sesons nd between 5.8 to 8.4 tons h -1 in the seson. Control (-N) tretment hd the lowest yield in both sesons. Overll, legume tretments, with or without N fertilizers produced between 19 to 58% more grin yield thn control (-N). Of the green mnure legumes screened, mucun, lblb nd sunhemp seem to be the most suitble green mnure legume cover crops for this re nd should be plnted in the erly summer seson to mximize biomss production nd N ccumultion. Use of green mnure legumes hs the potentil to increse mize yield in smllholder frms in Limpopo province. Key words: Green mnure legumes, mize, N fertilizer, smllholder frms. INTRODUCTION In Limpopo province of South Afric, the smllholder frms re locted mostly in the former homelnd res nd they cover pproximtely 30% of the provincil lnd surfce (White Pper on Agriculture, 1995). Most of the frms re locted on infertile degrded soils, where nutrient deficiencies, predominntly nitrogen limit the production of mize which is the min stple food. In ddition, vst prt of the province where mjority of the smllholder frms re locted is semi-rid. Due to the limited finncil resources of these smllholder frmers, very little or no fertilizers re pplied to their crops, leding to very low production, primrily for subsistence nd little mrketble surplus. Therefore, in order to mintin mize productivity in these smllholder systems, the integrtion of the smll mounts of nitrogenous (N) fertilizers pplied by the frmers long with N from Green Mnure Legume (GML) cover crops my offer strtegy to meet the N needs of the smllholder frmers. Short durtion fllows with cover crops nd grin legumes hve been shown to considerbly increse succeeding mize yields (Blsubrmnin nd Nguimgo, 1993; Horst nd Herdter, 1994; Ile et l., 1996; Crsky et l., 2001). Mize grin yields of greter thn 4 Mg h -1 were

2 Kiser 063 Tble 1. Some chemicl nd physicl properties of the soil from the 0-20 cm depth t the experimentl site. Prmeter mesured Vlue ph Orgnic Crbon (%) Phosphorus (mg kg -1 ) Totl Nitrogen (%) N (cmolc kg -1 ) K (cmolc kg -1 ) 0.14 C (cmolc kg -1 ) 3.08 Mg (cmolc kg -1 ) 1.75 CEC (cmolc kg -1 ) 5 Snd (%) Silt (%) Cly (%) ph ws determined in 1:2.5 (Soil: wter). Orgnic crbon ws determines by Wlkley Blck method. 3 Phosphorus ws determined by Bry 1. 4 Totl N determined by the Kjeldhl 5 method. Exchngeble ctions nd CEC determined by Ammonium cette extrction. Prticle size ws determined by the hydrometer method. obtined in southern Cmeroon fter short term fllow with Mucun pruriens (Huser nd Nolte, 2002). Green mnuring my lso help mintin or build orgnic mtter which will in turn help improve the soil s structure, pore size, wter holding cpcity nd inorgnic fertilizer use efficiency (through incresed ction exchnge cpcity). Despite the widespred use of GML cover crops by smllholder frmers in most tropicl res to improve soil fertility (N nd orgnic mtter), this prctice is yet to tke root mongst smllholder frmers in Limpopo province. GML re widely used to improve soil fertility in some commercil frms nd in the sugrcne belt re in Kwzulu Ntl province. The objectives of this study ws therefore to (1) screen number of green mnure legume cover crop species in order to determine their suitbility for the region nd (2) to determine the effect of green mnure nd nitrogen fertilizer on mize yield. MATERIALS AND METHODS This study ws conducted in Thohoyndou, Limpopo province of South Afric locted pproximtely S nd E. The climte is chrcterized by rid nd semi-rid, with n nnul rinfll of ±500 mm per nnumn nd temperture rnge from minimum of 10 C during winter to mximum of 40 C during summer. The site is chrcterized by deep well-drined cly soil. Field experimentl set-up Green mnure legume screening experiment Five GML cover crops, mucun, sunhemp, lb-lb, cowpe nd butterfly pe were screened during the winter sesons of 2005 nd 2006 nd the summer sesons of nd The legumes were plnted in plots mesuring 5 5 m nd rrnged in rndomized complete block design with three replictions. The legumes were llowed to grow for period of between 3-4 months before biomss production ws determined. Above-ground nd root biomss production ws determined by smpling from n re mesuring 1m 1m rndomly within the plots, by uprooting whole plnts nd seprting the shoots from the roots. The roots were then wshed thoroughly to remove ll the soil prticles. The plnt mteril ws dried t 70 C for t lest 48 h before weighing to determine the biomss yield. The mteril ws then ground, nd nlyzed for totl nitrogen nd crbon using Dums dry combustion method. Mize, N fertilizer nd green mnure experiment The best-bet legumes bsed on the screening experiment (mucun, sunhemp, nd lb-lb) were then evluted to determine their effect on mize grin yield with or without nitrogen fertilizer. The three legumes were plnted in plots mesuring 5 m 5 m rrnged in completely rndomized block design. Two control plots [(control (+N) nd control (-N)] were lso included in the tretments. After 3-4 months, biomss ws determined nd the legumes incorported into the soil. The tretments imposed were mucun, sunhemp, lblb, nd control with (75 kg N h -1 ) or without (0 kg N h -1 ) N fertilizer. The N source used in the fertilizer treted plots ws Lime Ammonium Nitrte (LAN) (28% N). The 75 kg N h -1 ws split pplied with 50 kg N h -1 pplied t plnting nd 25 kg N h -1 pplied s top-dress. Phosphorus ws pplied uniformly to ll the plots t rte of 50 kg h -1 s super grow (20.3%P). Mize (hybrid SNK 2147) ws then plnted t spcing of 90 cm 25 cm (44444 plnts per h -1 ) pproximtely 2 weeks fter incorportion of GML residues. Mize ws hrvested t mturity to determine the grin yield. Sttisticl nlysis Using rndomized complete block design model, nlysis of vrince ws conducted using the Generl LINEAR Model (GLM) procedure of SAS softwre version 9.1 (SAS Institute, Inc., 2003). The LSD test ws used to seprte the tretment mens. RESULTS Soil chrcteristics nd temperture dt Some soil physicl nd chemicl properties of the experimentl site re shown in Tble 1. Averge dily temperture during the winter screening trils ws 19.5 nd 17.7 C in 2005 nd 2006, respectively. Averge dily temperture during the summer screening trils ws 23.8 nd 25.4 C in nd sesons, respectively. Green mnure screening In the screening trils, legume biomss yield rnged between 41 (sunhemp) to 1672 kg h -1 (lblb), while the N content rnged between 2 (sunhemp) to 58 (cowpe)

3 Odhi mbo 064 Afr. J. Soil Sci. Tble 2. Green mnure bove-ground nd root biomss nd N uptke during winter screening. Cover crop Winter 2005 Biomss (kg h -1 ) N Uptke (kg h -1 ) Root biomss (kgh -1 ) N uptke (kg h -1 ) Mucun Sunhemp 41 b 2 b 20 b 0.3 b Lblb Cowpe NS NS NS NS Butterfly pe DNG DNG DNG DNG CV (%) Winter 2006 Mucun 685 b 25 b 43 bc 0.8 b Sunhemp 705 b 23 b 91 b 1 b Lblb 1, b Cowpe 1, Butterfly pe 54 b 3 b 25 c 0.6 b CV (%) NS - No sufficient biomss to smple. DNG - Did not germinte due to very low precipittion. Tble 3. Green mnure bove-ground nd root biomss nd N uptke during summer screening. Summer Cover crop Biomss (kg h -1 ) N Uptke (kg h -1 ) Root biomss (kg h -1 ) N uptke (kg h -1 ) Mucun 3,681 b 70 b 449 b 7 b Sunhemp 1,561 c 28 c 390 bc 4 b Lblb 6, Cowpe 899 c 27 c 223 c 4 b Butterfly pe 1,623 c 56 b 306 bc 5 b CV (%) Summer Mucun 9,772 b bc 16 b Sunhemp 13, , Lblb 8,701 bc 198 b 947 b 15 b Cowpe 4,044 cd 168 b 234 d 3 c Butterfly pe 2,108 d 73 b 594 c 12 b CV (%) kg N h -1 in the winter trils (Tble 2). Biomss yield produced during the winter period of 2005 were generlly lower thn in winter period of Root biomss yield rnged between 20 (sunhemp) to 222 (lblb) kg h -1 nd contributed between 0.3 (sunhemp) nd 4 (lblb) kg N h -1. High coefficients of vritions (CV s) were observed in both periods of the screening tril. In the summer trils, biomss yield rnged from 899 (cowpe) to kg h -1 (sunhemp), while the N content rnged between 27 (cowpe) to 302 kg N h -1 (sunhemp) (Tble 3). In the summer sesons, lblb produced significntly higher boveground biomss nd ccumulted significntly higher mount of N thn ll the GML. In the sesons, sunhemp produced significntly higher biomss thn lblb, cowpe nd butterfly pe, but ws not different from mucun. Root biomss rnged between 223 to 4009 kg h -1 for cowpe nd sunhemp, respectively nd contributed between 4 (cowpe nd sunhemp) nd 40 (sunhemp) kg N h -1. Generlly, the coefficients of vritions recorded during the summer seson trils were much lower thn during the winter screening trils. Mize, N fertilizer nd green mnure experiment Green mnure bove-ground nd root biomss nd N uptke prior to incorportion nd plnting of mize in

4 Kiser 065 Tble 4. Green mnure bove-ground nd root biomss nd N uptke preceding the mize crop plnted in 2006/7 nd 2007/8 sesons. Cover crop Biomss (kg h -1 ) Seson N Uptke (kg h -1 ) Root biomss (kg h -1 ) N uptke (kg h -1 ) Mucun 482 b b 1 Sunhemp b Lb-lb 313b b 0.4 b CV (%) Seson Mucun 4, b ND Sunhemp 5, ND Lb-lb CV (%) 4, b 17.8 ND ND ND. Not determined Figure 1. Mize grin yield nd sesons re shown in Tble 4. Aboveground biomss yield rnged from 313 (lb-lb) to 5773 kg h -1 (sunhemp), while the N content rnged between 13 (lb-lb) to 162 kg N h -1 (sunhemp). Aboveground biomss production ws much lower in 2006 s compred to Root biomss rnged between 25 (lblb) to 984 (sunhemp) kg h -1. Mize yield following GML rnged between 4.0 to 6.4 tons h - 1 in the sesons (Figure 1) nd between 5.8 to 8.4 tons h -1 in the sesons (Figure 2). Control (-N) tretment hd the lowest yield in both sesons. DISCUSSION Results obtined from the screening trils indicte tht best GML growth, biomss production nd N ccumultion re ttined when the legumes re plnted during the summer seson. The low tempertures during winter severely limit the growth, biomss production nd N ccumultion of the legumes. However, with the exception of winter 2005, the biomss yield nd N content obtined in winter 2006 compred well with results obtined elsewhere (Jernym et l., 2000) except for butterfly pe.

5 066 Afr. J. Soil Sci (+N) 8000 (-N) 7000 Grin yield (kg h -1) Mucun Sunhemp Lblb Control Figure 2. Mize grin yield sesons. Biomss yield nd N ccumultion obtined during summer seson is however much higher thn reported in most literture. This my be ttributed to the high rinfll nd tempertures during the summer seson which my be fvourble for the growth of the GML. Bsed on biomss production nd N ccumultion, sunhemp, mucun nd lblb seem to be the best-bet legumes for this region. However, becuse the min cropping seson in this region is during summer, nd given the shortge of lnd due to high popultion density, very few frmers my be willing to hve their lnd under GML insted of food crops. Three vible options my be dopted by the frmers. The first option my be suitble for frmers with enough lnd to llow for green mnure fllow during summer, or rottion system (green mnure-mize) nd terminte the green mnure growth t flowering time nd leve the residues on the soil surfce to decompose until the next plnting seson. Results obtined by Odhimbo et l. (2009) from two yer study on green mnure-mize rottion system in Limpopo province showed tht cowpe, mucun, lblb, butterfly pe nd sunhemp tretments gve yield increses of 77, 85, 134, 125 nd 103%, respectively, bove the control (-N) tretment. The limittion of using this option is tht lnd in this region is communlly owned nd fter hrvest, livestock is llowed to grze communlly in the frms nd therefore poses the risk of the residues being eten up by the nimls. The second option my be to estblish the GML in the erly spring nd incorporte during summer, prior to plnting mize. Due to the dry conditions tht previl during erly spring, this pproch my be suitble for frmers in irrigtion schemes who normlly strt plnting mize in erly spring due to vilbility of wter. A study by Odhimbo nd Netshivhodz (2008) conducted in smllholder frms t two irrigtion schemes using this option showed tht green mnure lone incresed mize grin yield significntly compred to the control (-N). A combintion of GML (mucun, sunhemp, lblb nd cowpe) nd 60 kg N h -1 gve yield increment of between 23 to 118%. The third option mybe to rely plnt or intercrop the GML with mize. This pproch ws not evluted in this study but remins vible option. In terms of mize grin yield following green mnure incorportion, overll, legume tretments, with or without N fertilizers produced between 19 to 58% more grin yield thn control (-N). Studies conducted in the midltitude res of Ugnd hve shown tht Crotlri ochroleuc green mnure cn increse mize yield by 39% (Fischler et l., 1999). In Keny, verged over two yers, C.ochroleuc nd Mucun pruriens green mnure improved mize grin yield by 1.5 t h -1 compred to no incorportion (Ojiem et l., 2000), while in southern Cmeroon, Huser nd Nolte (2002) obtined mize yields greter thn 4 t h -1 fter short-term fllow with mucun. In Tnzni, frmers hve used sunhemp to increse their mize yield from 12.4 to 45 bgs h -1 (1116 to 4050 kg h -1 ) (Luptu nd Kilimwiko, 1991). Conclusions Of the green mnure legumes screened, mucun, lblb nd sunhemp pper to be the most suitble green

6 Kiser 067 mnure legume cover crops for this region. However, to mximize biomss production nd N ccumultion, the GML must be estblished t the pproprite time bsed on the frmer s circumstnces, for exmple, vilbility of enough lnd for fllow, wter for irrigtion, or prcticing of rely cropping or intercropping of the GML with mize. Use of green mnure legumes in combintion with N fertilizers hs the potentil to increse mize yield in smllholder frms in Limpopo province. ACKNOWLEDGEMENT This study ws prt of lrger study funded by the Ntionl Reserch Foundtion (NRF).The uthor wish to thnk the NRF for mking this study possible. REFERENCES Blsubrmnin V, Nguimgo, KAB (1993). Short seson fllow mngement for sustinble production in Afric. Technologies for sustinble Agriculture in the Tropics, ASA Specil publiction, p. 56. Crsky RJ, Becker M, Huser S (2001). Mucun cover crop fllow systems.: potentils nd limittions. In: Tin G et l. (eds.) Sustining soil fertility in West Afric. SSSA Specil Publictions 58. Soil Science Society of Americ Inc. Americn Society of Agronomy Inc., Mdison, WI, USA, pp Fischler M, Wortmnn CS, Feil B (1999). Crotlri ochroleuc s green mnure in mize-ben cropping systems in Ugnd. Field Crops Res., 61: Huser S, Nolte, C (2002). Biomss production nd N fixtion of five Mucun pruriens vrieties nd their effect on mize yields in the forest zone of Cmeroon. J. Plnt Nutr. Soil Sci., 165: Horst WJ, Herdter R (1994). Rottion of mize wit cowpe improves yield nd nutrient use of mize compred to mize monocropping in n lfisol in the northern Guine svnn of Ghn. Plt. Soil, 160: Ile E, Hmdin MK, Henrot J, Trih N (1996). Residul effects of previous Mucun pruriens on the performnce of mize. In: Neeteson JJ, Henrot J (eds) The Role of Plnt Residues in Soil Mngement for Food Production in the Humid Tropics. DLO-AB, Hren, The Netherlnds, pp Jernym P, Hestermn, OB, Wddington SR, Hrwood RR (2000). Rely-Intercropping of sunhemp nd cowpe in smllholder mize system in Zimbbwe. Agron. J., 92: Luptu M, Kilimwiko L (1991). Nturl fertilizers: New life for tired soils. Afric Frmer No.6; December Published by the Hunger Project Svccon gllery, 240 E. 13 th street New York. NY USA. Odhimbo JJO, Netshivhodz MH (2008). Green mnure legume cover crops for improving soil fertility in smllholder frms. Poster pper presented t the Soil Science Society of South Afric (SSSSA), South Africn Society of Crop Production (SASCP), South Africn Weed Science Society (SAWSS) nd Southern Afric Society for Horticulturl Sciences (SASHS) Combined Congress held between Jnury 2008 t Rhodes University, Grhmstown, South Afric. Odhimbo JJO, Ogol JBO, Mdzivhndil T (2010). Effect of green mnure legume mize rottion on mize yield nd weed infesttion levels. Afr. J. Agric. Res., 5(8): Ojiem JO, Mureithi JG, Okwuos EA (2000). Integrted mngement of legume green mnure, frmyrd mnure nd inorgnic nitrogen for soil fertility improvement in western Keny. In: Mureithi et l. (eds) Prticiptory Technology Development for Soil Mngement by Smllholders in Keny. Proceedings of the 2 nd Scientific Conference of the Soil Mngement nd Legume Reserch network projects. June 2000, Mombs, Keny, pp SAS Institute (2003). SAS/STAT Softwre. Relese 9.1 SAS Institute, North Crolin, USA. White Pper on Agriculture (1995). Limpopo Province, Deprtment of Agriculture, Pietersburg, South Afric. ISBN x.