Grain Legumes and Green Manures for Soil Fertility in ... - cimmyt

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Other weeds 12% C. indrostachys T. radicans 49% 22% R. hirsuta,__--IOCIf""", 6% Figure 2. Weed composition of a maize field abandoned soon after crop establishment due to lack of fertilizer inputs in Chinyika smallholder farming area, Zimbabwe Chamaecrista absus 0.4% • Crola/aria microcarpa fl C. cytindroslachys Kl Chamaecrisla absus [j /ndigofera aslraga/ina 1lI/. Demisa III Rolhia hirsula ~ Tephros/a radicans • Other IIeeds 14 T"'......~~-"-"'O:"'""'..................---,......,,-.,. .wOO ~ g 12 3500 ~ ~ _ 10 3000 "" g o~ ." n -; 8 ..... 2500 e_ ~ :; 2000 :: ~ on E 6 .. "" .. 0 w:E ~ 4 " go ...J 1500 ~ 1000 ~ 2 500 ... ~ o o Chlkwaka Chlnylka Zlmuto Site 1_%LegulTIII -+-Total Productivity I Figure 3. Legume biomass contribution to total biomass product under a one·year natural fallow in smallholder farming areas across three agro·ecologicai regions in Zimbabwe Legume diversity and adaptability Diversity of legumes was higher in the relatively new resettlement area of Chinyika, where smallholder cropping has been taking place for about 20 years, than in the old smallholder farming areas of Chikwaka and Zimuto where cultivation had been going on for over 70 years. The trend on legume diversity contrasted with the pattern in biomass produ£tivity, which showed a decline in legume biomass from Chikwaka (-12% of total), a high rainfall area, to Zimuto (-3%) a semi-arid area. This suggests a loss of legume diversity in the old communal (smallholder) areas of Chikwaka and Zimuto, and we attributed this to continuous depletion of the seed bank due to continuous cultivation coupled with clean weeding approaches. However, the 88% contribution by legumes to total biomass productivity in an abandoned field suggests that boosting the population density can enhance the legume contri Table 2. Major soil characteristics for selected fallowed field sites on which indigenous herbaceous legumes were naturally growing in smallholder areas of Zimbabwe Areas and Farmer's %Clay %Sand pH Olsen P %C Agro·region Name (H2O) (ppm) Chikwaka Kaseke 6 85 4.8 3 0.40 NR II Mutawu 6 87 5.5 1 0.33 Tafirenyika 6 83 5.3 1 0.32 Chinyika Majaji 9 78 5.8 3 0.41 NR III Razio 13 75 6.0 1 0.49 liodoma 7 82 6.0 3 0.52 Zimuto Madhava 4 81 5.0 1 0.40 NRIV Makonese 8 81 5.3
Table 3. N, P and Kconcentrations (means of ~ 5 samples) of indigenous legume species sampled identified species by farmers from fields fallowed for asingle growing season in three smallholder farming areas across different themselves was fea-sible is agro·regions in Zimbabwe indicative of the potential to Species Nutrient Concentration manipulate legume densities in the stands, once the popu Chikwaka (NR II) Chinyika (NR III) Zimuto (NR IV) lation dynamics are under 'lioN %P %K %N %P %K %N %P %K stood. We consider Indifal Alysicarpus ovalifolius 1.53 0.04 0.73 lows as a technology for Chamaecrista absus 1.19 0.11 0.77 those poor and vulnerable C. rotundifolia 2.12 0.08 1.75 farmers for whom current C. mimosoides 1.45 0.07 1.44 1.45 0.05 0.48 research and development Crotalaria cylindrostachys 1.63 0.09 2.11 2.09 0.09 2.33 1.77 0.06 1.79 initiatives have failed to C. laburnifolia 5.02 0.12 1.04 draw their participation. C. microcarpa 2.09 0.08 1.71 .1.99 0.18 2.19 2.81 0.11 1.14 These poor groups often C. pisicarpa 2.67 0.08 1.14 Eriosema ellipticum 1.62 0.05 0.99 lack minimal cash require Indigofera astragalina 1.95 0.08 0.89 1.62 0.14 2.16 1.18 0.04 0.33 ments to invest into cur I. demisa 1.81 0.10 1.28 rently available soil fertility I. flavicans 1.71 0.05 1.29 technologies. The challenge, I. praticola 1.74 0.13 1.14 however, is that of develop I. vicioides 1.41 0.07 1.75 2.59 0.11 1.24 ing strategies for integration I. wildiana 2.38 0.10 0.84 of these legumes into exist Macrotyloma daltonii 1.66 0.06 1.14 Rothia hirsuta 1.59 0.09 1.72 1.91 0.10 2.44 1.66 0.06 1.02 ing cropping systems, and Tephrosia longipes 1.32 0.05 0.33 defining the practical do T. purpurea 1.76 0.04 0.43 5.88 0.04 0.73 main within which the tech T. radicap~ 2.22 0.07 1.19 nology can work. The exis Vigna vexillata 1.65 0.06 1.40 tence of regional research Zornia glochidiata 2.72 0.09 1.14 1.59 0.17 1.45 2.27 0.08 0.96 networks such as the TSBF Other weeds (mostly grasses) 0.75 0.07 0.73 0.63 0.07 1.35 0.69 0.05 0.59 CIA T African Network I Each value·is a mean of four samples; NR - natural (agro·ecologicalJ region; H implies amissing value due to absence 01 (AfNet) and Soil Fertility particular species in the sampling framework Network for Maize-Based 1. Abundant seeding to allow ready propagation Cropping Systems in Southern Africa (SoiIFertNet) and ready seed collection to reinforce populaand testing of Indifallow technologies on a regional provide an opportunity for a wider development tions. basis. 2. A long-lived seed bank. 3. Rapid establishment and growth. 4. Adaptation to poor soils with restricted availability of phosphorus. Conclusions 5. Good N2-fixing potential in terms of spontaneous nodulation with indigenous rhizobia, good Several conclusions were drawn based on this ex nodulation potential and high N concentrations ploratory study. Results showed that smallholder in the shoots. farming systems across different agro-ecological re 6. Easy to remove by hand pulling or hoeing gions in Zimbabwe contain sufficient diversity of should weeding be required. indigenous herbaceous legumes to warrant more The legumes thatbestfit these characteristics are STrategic research on Indifallows as a component of largely annuals, biennials or short-lived perennials. integrated soil fertility management. However, there are indications that that current clean weeding Opportunities for Indifallows in small!:tolder practices recommended for these farmers may be farming systems contributing to loss of agro-biodiversity in farming The potential for Indifallows lie1' in the existence of systems. Most of the dominant species were evia diversity of annual legumes that can grow in their dently tolerant to poor fertility soils with low P and mixtures with little demand for management of inon pH levels, yet it was apparent that most of the soils terspecific competition. Unlike agroforestry improved fields fallowed by farmers in Zimbabwe are too fallows and annual green manures, which poor to support any meaningful cropping using the are often constrained by conditions of poor initial currently available low cost soil fertility technolo soil fertility, establishment costs and high labour gies. Although there is still need to establish why demands, the most significant cost variables for In farmers have not significantly exploited these re difallows are likely to be seed collection and sow sources over time, we advocate for a paradigm shift ing. The fact that seed collection for most of the in weed management approaches towards enhance- Grain Legumes and Green Manures for Soil Fertility in Southern Africa 73
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Grain Legumes and Green Manures for
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Acknowledgments • The Leopard Roc
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Evall!ating mucuna green manure tec
Page 9:
INTRODUCTION AND CONFERENCE OBJECTI
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Table 1. Paradigm shifts underlying
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100 90 80 - - 0 - - Uptake by ihe m
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- 6 ~ 9 8 7 0- 5 CḎ ns 4 0::: 3
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Table 3. Millet grain and total dry
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Dvorak KA 1996. Adoption potential
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LEGUMES FOR SOIL FERTILITY IN SOUTH
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to the system in such a way that th
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Muetzelfeldt, R.1. 1995. A framewor
Page 30 and 31: ing capacity. Legumes offer other b
Page 32 and 33: people/km2), land holdings are smal
Page 34 and 35: ments. It would help researchers to
Page 36 and 37: Own livestock Gununo farmers for th
Page 39: Questions and Answers ~ey Papers To
Page 42 and 43: Historical Perspective on Soyabean
Page 44 and 45: ganic amendment for resource-poor f
Page 46 and 47: MPhil. Thesis. University of Zimbab
Page 48 and 49: deal of research work has been bias
Page 50 and 51: 1600 '7 ns 1400 ~ 1200 Cl ~ 1000 "C
Page 52 and 53: Arbuscular mycorrhizal fungi (AMF)
Page 54 and 55: Boswell EP, Koide RT, Shumway DL, A
Page 56 and 57: Materials and Methods The trial was
Page 58 and 59: 0.9 0.8 ~ 0.7 Rec '-' 0.6 Vl ::9 0.
Page 60 and 61: Series no 5. Soil Science SOciety o
Page 62 and 63: Materials and Methods Persistence o
Page 64 and 65: content resulted in increased rhizo
Page 66 and 67: (Mugwiia and Murwira, 1997). Howeve
Page 68 and 69: Table 2. Average maize yield estima
Page 70 and 71: implied that most fanners prefer to
Page 73 and 74: ] Questions and Answers Rhizobium,
Page 75 and 76: ADDING A NEW DIMENSION TO THE IMPRO
Page 77 and 78: Materials and Methods The study use
Page 79: a) Chikwaka b) Chinyika !21 C. absu
Page 83 and 84: Abstract SCREENING OF SHORT DURATIO
Page 85 and 86: Table 2. Characteristics of short d
Page 87 and 88: RISK DIVERSIFICATION OPPORTUNITIES
Page 89 and 90: management technologies with differ
Page 91 and 92: Table 3. Expected annual returns (Z
Page 93: Table 6. Risk diversification indic
Page 96 and 97: een renewed interest in green manur
Page 98 and 99: unfertilised maize crop of over 200
Page 101 and 102: Questions and Answers Screening of
Page 103 and 104: GREEN MANURE AND FOOD LEGUMES RESEA
Page 105 and 106: 7000 6000 ';' €.. 5000 .~MzSole :
Page 107 and 108: Table 5. Maize grain yield (kg ha")
Page 109: Phiri, A.D.K. 1999. Effects of Sesb
Page 112 and 113: amount of roots with sl:nnhemp. It
Page 114 and 115: It was proved that a mixed farming
Page 116 and 117: Table 3. Above·ground biomass (t/h
Page 118 and 119: and horticulture in Zimbabwe: Case
Page 121 and 122: GRAIN LEGUMES AND GREEN MANURES IN
Page 123 and 124: Results Table 1. Adaptation of gree
Page 125 and 126: Four rates of fertilizer N were app
Page 127 and 128: THE ROLE OF COWPEA (VIGNA UNGUICULA
Page 129 and 130: Table 1. Non-legume cropping patter
Page 131 and 132:
Table 9. Common pests on cowpeas as
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few of the farmers interviewed acqu
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Murwira, H.K., M.J. Swift and P.G.H
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Materials and Methods On farm exper
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18000 1600) 14000 a) Zambia 12000 m
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EFFECT OF DIFFERENT GREEN MANURE LE
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.. ~ Table 2. The effect of time o
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Chivinge, O.A., E. Kasembe, and I.K
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times with regionally specific adap
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ter content at 180 cm was still wel
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to amount of biomass, quality of bi
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with the natural fallow, which did
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and K to maize as an equivalent amo
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forts to understand the mechanisms
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gen recovery rates in relation to p
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The first steps to improve soil fer
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Questions and Answers .Identificat
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MUCUNA - MAIZE ROTATIONS AND SHORT
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Table 3. Percent nitrogen (% N) con
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~e decomposition of legume residues
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Table 3. Effect of forage legumes o
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available nutrients and vice versa,
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Conclusion and Recommendation Mucun
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Specific objectives were to: • Te
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'"~ v '" ~ ~ 1400000 1200000 100000
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EFFECT OF SURFACE APPLICATION AND I
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it 4 a···· · ... - :.!! e.....
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PERFORMANCE OF GREEN MANURES AND GR
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Mungwi soil, cowpea and soyabean pr
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Among BNF systems, symbiotic system
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3500 .f"'3000 ca ,c2500 CI "" - 200
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above-ground biomass was not transl
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3000 "0 ]i >. ,5 ~ C> 800 600 400 2
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Most interventions involving green
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~ ~~----.-~r-~-------------r~~ Aoo
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stover N, followed by after pigeon
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tems in Malawi and Zimbabwe. Procee
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1965). The tailings and AgLi were a
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The significant soybean yield could
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twice the yield is necessary. We ha
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Table 1. Maize and Grain Legumes Pr
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Recommendations and Conclusion In v
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performance of private sector compa
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the investment costs incurred. The
Page 228 and 229:
Results and Planning Workshop. Soil
Page 231 and 232:
A SOCIO-ECONOMIC ANALYSIS OF LEGUME
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Table 1. Gross margins from the dif
Page 235 and 236:
Abstract LINKING TECHNOLOGY DEVELOP
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3. If households are linked to prod
Page 239 and 240:
Table 9. Average Table 8. Pigeonpea
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ance of sorghum-pigeonpea intercrop
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Mligo, J.K., 1995. Pigeonpea breedi
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To Charles Nhemachena, et al. Q: 1)
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• Assessment of the potential ben
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few studies characterized the house
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• Conduct more research to measur
Page 254:
Socio-Economics, Policy and Technol
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