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

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twice the yield is necessary. We have to consider these effects clearly and cost them. C: Both leaving land fallow with non-food legumes or growing maize after maize may'face a problem of adoption. There are agronomic management systems that minimize competition and improve the compatibility of components in intercropping systems. Growing legumes under early maturing maize may give better opportunities to minimize risk and increase profitability per unit land area over seasons. C: Almost all the papers presented on legumes (grain or green manure) assume that the crop residue is incorporated into the soil by farmers. But often livestock is a major component of the systems, and farmers give priority to their livestock rather than soil fertility when it comes to decision-making. We have to reconsider our work to integrate and evaluate it as it affects the whole production system. C: Various nutrient deficiencies occur in tropical soils and this may confound responses to the application of only a limited number of nutrients. In practice it is important to apply sufficient levels of all nutrients except the one being investigated to obtain predictable and explainable responses. There are many options with providing N, e.g. manures, N2 fixation, N fertilizer, if all other nutrients are adequate. C: Often in the presentations we hear the statement "the treatments were not significantly different, but they were different". If we are going to ignore the results of our statistical tests, why bother doing them? Also we should not accept a significant difference as meaning a treatment is viable - the question is, does it show a significant economic benefit? 210 Grain Legumes and Green Manures for Soil Fertility in Southern Afriea
Abstract EVALUATION AND PROMOTION OF VARIOUS CLASSES OF ANNUAL LEGUMES WITH FARMERS IN 'CHIOTA, ZIMBABWE DORAH MWENYE AREX, Marondera District, PO Box 150, ('V1arondera, Zimbabwe Nitrogen is one of the most limiting crop nutrients in crop production. It is important, therefore, to' identify and utilize all available sources of nitrogen, particularly those that are readily available and generally affordable by resource poor farmers. Green manure and cereal - legume rotations can be practiced to supply nitrogen. Green manures must be managed well to produce a significant fertilizing effect on the following crop. This is particularly important for the smallholder farmer who is sacrificing a food crop for one year through this practice. Smallholder farmers have practiced cereal - legume rotations for many years using legumes such as groundnut, bambara nut and field bean . Oespite this practice of crop rotation, the problem 'of low soil fertility has persisted resulting in low maize yield. Generally, the use of mineral fertilizers has declined over the years due to high input costs. Hence, the objective of this work was to introduce better N-fixing legumes to improve soil fertility. Velvet bean, sunnhemp and soyabean were introduced. Farmer participatory research methods were used for three years. Research and extension worked with identified farmer groups in a multidisciplinary approach. Th~ evaluation and promotion of technologies was carried out during farmer feedback sessions and field days. The major problems encountered in the promotion of these legumes included the unavailability of seed material locally, and lack of knowledge on the management aspects of the legumes to attain the optimum biomass. Legume cereal rotations were widely accepted, whilst green manures were accepted to a lesser extent. The results from the pilot project indicated that 29% of the farmers used the green manure and 57% the soyabean + cereal rotation. Maize yields from different sites increased by 15-70% for green manures and by 40-100% for the rotations. Farmers take up technologies within given domains so there is a need to come up with green manure or legume fertility packages for different farmers in their agro-ecological zones. An impact assessment would best indicate the results of this multidisciplinary approach. Key words: Annual legumes, farmer participatory research and extension, technology promotion, adoption potential, impact Introduction Nitrogen reserves in the soil are difficult to build due to its liability to leaching losses. It is important, therefore, to identify and utilize aU sources of nitrogen, particularly those that are readily available and generally affordable by resource poor farmers. Green manure and cereal legume rotations can be practiced as important ways to supply nitrogen. Green manures must be managed well to produce a significant fertilizing effect on the following (usually cereal) crop. This is particularly important for the smallholder farmer who is sacrificing a food crop for one year through this practice. Smallholder farmers have practiced cereal-legume rotations for many years, particularly focusing on grain legumes such as groundnut, bambara nut and edible bean. The area allocated to bambara nut is so insignificant that it can give little impact (AGRITEX, 1998-2002). Despite crop rotation, the problem of low soil fertility persists and maize yields continue to decline. Generally, the use of inorganic fertilizers has declined since the early 1990s, mainly due to high input costs. Hence there was need to introduce better performing legumes that have good nitrogen fixation abilities. For green manures, velvet bean (Mucuna spp.) and sunnhemp (Crotolaria juncea) were introduced. With cereal-legume rotations, soyabean was introduced as a new legume. A pilot project was set up with Soil Fert Net to evaluate Best Bet soil fertility technologies with farmers from Chiota Communal Area of Mashonaland East Province in Zimbabwe. The major goal of the project was to expose approximately 4000 Grain Legumes and Green Manures for Soil Fertility in Southern Africa 211
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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
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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
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ing capacity. Legumes offer other b
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people/km2), land holdings are smal
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ments. It would help researchers to
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Own livestock Gununo farmers for th
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Questions and Answers ~ey Papers To
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Historical Perspective on Soyabean
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ganic amendment for resource-poor f
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MPhil. Thesis. University of Zimbab
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deal of research work has been bias
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1600 '7 ns 1400 ~ 1200 Cl ~ 1000 "C
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Arbuscular mycorrhizal fungi (AMF)
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Boswell EP, Koide RT, Shumway DL, A
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Materials and Methods The trial was
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0.9 0.8 ~ 0.7 Rec '-' 0.6 Vl ::9 0.
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Series no 5. Soil Science SOciety o
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Materials and Methods Persistence o
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content resulted in increased rhizo
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(Mugwiia and Murwira, 1997). Howeve
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Table 2. Average maize yield estima
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implied that most fanners prefer to
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] Questions and Answers Rhizobium,
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ADDING A NEW DIMENSION TO THE IMPRO
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Materials and Methods The study use
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a) Chikwaka b) Chinyika !21 C. absu
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Table 3. N, P and Kconcentrations (
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Abstract SCREENING OF SHORT DURATIO
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Table 2. Characteristics of short d
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RISK DIVERSIFICATION OPPORTUNITIES
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management technologies with differ
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Table 3. Expected annual returns (Z
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Table 6. Risk diversification indic
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een renewed interest in green manur
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unfertilised maize crop of over 200
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Questions and Answers Screening of
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GREEN MANURE AND FOOD LEGUMES RESEA
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7000 6000 ';' €.. 5000 .~MzSole :
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Table 5. Maize grain yield (kg ha")
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Phiri, A.D.K. 1999. Effects of Sesb
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amount of roots with sl:nnhemp. It
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It was proved that a mixed farming
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Table 3. Above·ground biomass (t/h
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and horticulture in Zimbabwe: Case
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GRAIN LEGUMES AND GREEN MANURES IN
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Results Table 1. Adaptation of gree
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Four rates of fertilizer N were app
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THE ROLE OF COWPEA (VIGNA UNGUICULA
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Table 1. Non-legume cropping patter
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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
Page 167 and 168: Questions and Answers .Identificat
Page 169 and 170: MUCUNA - MAIZE ROTATIONS AND SHORT
Page 171: Table 3. Percent nitrogen (% N) con
Page 174 and 175: ~e decomposition of legume residues
Page 176 and 177: Table 3. Effect of forage legumes o
Page 178 and 179: available nutrients and vice versa,
Page 180 and 181: Conclusion and Recommendation Mucun
Page 182 and 183: Specific objectives were to: • Te
Page 184 and 185: '"~ v '" ~ ~ 1400000 1200000 100000
Page 187 and 188: EFFECT OF SURFACE APPLICATION AND I
Page 189: it 4 a···· · ... - :.!! e.....
Page 193 and 194: PERFORMANCE OF GREEN MANURES AND GR
Page 195: Mungwi soil, cowpea and soyabean pr
Page 198 and 199: Among BNF systems, symbiotic system
Page 200 and 201: 3500 .f"'3000 ca ,c2500 CI "" - 200
Page 202 and 203: above-ground biomass was not transl
Page 204 and 205: 3000 "0 ]i >. ,5 ~ C> 800 600 400 2
Page 206 and 207: Most interventions involving green
Page 208 and 209: ~ ~~----.-~r-~-------------r~~ Aoo
Page 210 and 211: stover N, followed by after pigeon
Page 212 and 213: tems in Malawi and Zimbabwe. Procee
Page 214 and 215: 1965). The tailings and AgLi were a
Page 216 and 217: The significant soybean yield could
Page 220 and 221: Table 1. Maize and Grain Legumes Pr
Page 222 and 223: Recommendations and Conclusion In v
Page 224 and 225: performance of private sector compa
Page 226 and 227: the investment costs incurred. The
Page 228 and 229: Results and Planning Workshop. Soil
Page 231 and 232: A SOCIO-ECONOMIC ANALYSIS OF LEGUME
Page 233 and 234: Table 1. Gross margins from the dif
Page 235 and 236: Abstract LINKING TECHNOLOGY DEVELOP
Page 237 and 238: 3. If households are linked to prod
Page 239 and 240: Table 9. Average Table 8. Pigeonpea
Page 241 and 242: ance of sorghum-pigeonpea intercrop
Page 243: Mligo, J.K., 1995. Pigeonpea breedi
Page 246 and 247: To Charles Nhemachena, et al. Q: 1)
Page 248 and 249: • Assessment of the potential ben
Page 250 and 251: few studies characterized the house
Page 252 and 253: • Conduct more research to measur
Page 254: Socio-Economics, Policy and Technol
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