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

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stover N, followed by after pigeon pea, Tephrosia vcgelii and maize respectively (Table 9). This could be because Mucuna pruriim$ contributed the highest N through its easily mineralizable leafy residues. Generally, maize following green manure legumes had higher stover N than the continuously grown maize. This was expected since the green manure legume plots provided more N that the subsequent maize crop benefited from after mineralization. Maize grain yield. The type of preceding crop significantly influenced (P < 0.01) maize grain yield across the two experimental sites. The highest maize grain yield followed Mucuna pruriens (1104 kg ha- 1 ), then after Cajanus cajan (880 kg ha- 1 ), Tephrosia vogelii (785 kg ha- 1 ) and continuous Zea mays (627 kg ha- 1 ) (Table 10). These results are consistent with those by Kumwenda and Gilbert (1998). Their studies on green manure legumes in rotation with maize on exhausted soils of Malawi found that maize grain yield was the highest after a Mucuna pruriens fallow, followed by Crotalaria spp. and Tephrosia voge/ii fallows. Maize grain yield average for the second season could have been higher but lack of timely weeding at Nchenachena EPA and high rainfall received during the 2000/2001 season, at Champhira EPA adversely affected crop growth. The rate of fertilizer in the first season significantly influenced (P < 0.015) maize grain yield. The highest Table 9. The effect of a preceding crop on N content in maize stover at harvest Fallow sequence Maize stover nitrogen (kg ha"j Maize after maize 37.7' Maize after Mucuna pruriens 69.5 b Maize after pigeonpea 55.911> .Maize after Tephrosia vogel;; 44.6'b SED ± 8.79 CV % 26.8 Key: SED ±. Standard error of difference; CV, Coefficient of variation; NB: means followed by same letters are not statistically different Table 10. The effect of preceding crop species on subsequent maize grain yield (kg ha·1) at Champhira and Nchenachena Fallow sequence Champhira Nchenachena Mean Maize after maize 986 268 627' Maize after Mucuna pruriens 1783 424 110411> Maize after Pigeon pea 1402 359 880' Maize after Tephrosia vogelii 1273 297 785' SED ± 126.3 CV % 23.5 Key: SED±, Standard error of difference; CV, Coefficient of variation; NB: Means followed by same letters are not statistically different; Sites 1and 2 are Champhira and Nchenachena maize grain was from the treatment that received 20 kg P20S + 4 5 ha- 1 followed by 40 kg P20S + 8 kg 5 ha- 1 , The treatment without inorganic fertilizer had the least mean maize grain (Table 11). This suggests an optimum fertilizer rate at 20 kg PiOs + 4 5 kg ha- 1 . The higher rate of inorganic fertilizer, 40 kg P20S + 8 kg 5, slightly reduced grain production. High N fertilizer promotes succulence and more vegetative plant material at the expense of reproductive organs. The response of the second season maize crop to the application of inorganic fertilizer showed that yield of maize grain after Mucuna pruriens was the highest followed by that of pigeonpea, Tephrosia vogelii and maize (Figure 4). Maize grain yield after maize and pigeonpea was depressed at the higher rate of fertilizer application (40 kg P20S + 8 kg 5 ha- 1 ). This may be because the compound inorganic fertilizer used has nitrogen, ~hich when applied at high rates tends to enhance vegetative growth and succulence at the expense of grain production. The other possible reason, particularly for maize, is that maize residues incorporated at harvest after the first season had a low N content, unlike Mucuna pruriens, pigeonpea and Tephrosia z:ogelii (Table 3). The low N content could have caused net immobilization of nutrients, particularly nitrogen, from its residues. Crop residues of low quality, i.e. less than 2 % nitrogen can result in poor growth of the succeeding cereal crop since the N requirement of the crop is not in synchrony with N mineralization (Nandwa et al., 1995). Table 11. Effect of inorganic fertilizer rate on maize grain yield Rate of fertilizer Maize grain yield -----(kg ha'j---- No fertilizer 708' 20 kg P205 + 4 kg S 921 b 40 kg P205 + 8 kg S 918 b SED ± 78.8 CV % 29.4 Key: SED ±, Standard error of difference; CV, Coefficient of variation; NB: means followed by same letters are not statistically different 1400 1200 ~ 1000
Maize grain yield after the green manure legumes was higher compared with that after maize, but among the three green manure legume crops it was . m.aize after Mucuna pruriens that gave the highest grain yield. The likely reason is that Mucuna pruriens produced the most biomass, besides having residues that had a relatively high N content. Conclusions The green manure legume crops tested in this study responded to the application of inorganic fertilizer and an increased rate of inorganic fertilizer produced more dry matter. The response to fertilizer was greatest between the unfertilized control and the lower rate of fertilizer application (20 kg P20S + 4 kg S ha- I ). Among the three candidate green manure legume crops tested, Mucuna pruriens is the superior, giving the highest dry matter production. It is therefore the best candidate green manure legume crop for improving soil fertility. Another good candidate was Tephrosia vogelii, which at the time of incorporaiion gave the highest nitrogen content in its tissue. Maize gave the greatest response to inorganic fertilizer among the four crops tested whereas Tephrosia vogelii responded most favourably among the green manure legume crops. Cajanus cajan was the least responsive. Maize residues however, had the least content of nitrogen, a factor disc;.ualifying it as a potentiat green manure crop in low input systems and soils with low fertility. Maize grain yield after the short-term fallow was higher after the green manure legume crops than after maize. Maize grain and biomass produced was highest after Mucuna pruriens. Inorganic fertilizer, particularly at the lower rate, had a positive residual effect on maize grain yield. The higher rate of inorganic fertilizer gave the most remarkable positive effect on total maize biomass production. Recommendations Application of modest amounts of phosphorus and sulphur fertilizer (20 kg P20S + 4 kg S ha- I ) to green manure legume crops should be adopted to improve the litter quality of these organic fertilizers as well as enhance their growth and subsequent dry matter production. Straight inorganic fertilizer sources of phosphorus, sulphur and nitrogen should be used in further studies to isolate the individual effects of these nutrient elements as well as their interactive effects. Other critical nutrient elements such as zinc and molybdenum have to be tested in experiments where green manure legumes are screened for response to inorg'anic fertilizers. Mucuna pruriens should be promoted as a potential soil fertility-improving crop where soil fertility is low. The effect can be seen. in as short a fallow as one season. Long-term studies of the residual effects of green manure legume crops on soils, as well as on cereal crop yields, should be conducted to ascertain sufficient information about the benefits of the shortterm fallow system. Acknowledgements We are grateful to the Rockefeller Foundation for providing funds for the research. References Eaglesham, A.RJ. and A. Ayanaba. 1984. Tropical stress ecology of Rhizobia, root nodulation and legume fixation. In: Subba Rao, N.5. (ed.) Current Oevelopments in Biological Nitrogen Fixation. 42 p. Gilbert, RA. 1998. Growth Characteristics and N balance of Maize - Green manure intercropping systems in Malawi. In: J.D.T. Kumwenda and M. K.M. Komwa (ed.) Annual Report for 1997/98 season for the Cereals Commodity Group, volume 1. Chitedze Agricultural Research Station, Lilongwe, Malawi. pp. 217-223. Giller, K.E. and K.J. Wilson, 1991. Nitrogen Fixation in Tropical Systems. CAB International, Wallingford, England. p. 43. Giller, K.E. and G. Cadish. 1995. Future benefits from biological nitrogen fixation: An ecological approach to agriculture. Plant and Soil 174:225~ 277. Kumwenda, J.D.T. and R Gilbert. 1998. Legume biomass production and maize yield response in legume manure rotations in Malawi. In: JD.T. Kumwenda and M.K.M. Komwa (ed.) Annual Research Project Report for the 1997/98 season for the Cereals Commodity Group. pp. 148-159. Kumwenda, J.D.T. and R, Gilbert. 1998. Biomass production by legume green manures on exhausted soils in Malawi: A Soil Fertility Network Trial. In: Waddington, S.R; Murwira, H.K.; Kumwenda, J.D.T.; Hikwa, 0; Tagwira, F. (eds). ~oil Fertility Research for Maize-Based Farming Sys Grain legumes and Green Manures for Soil Fertility in Southern Africa 203
Page 2 and 3:
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
Page 160 and 161: forts to understand the mechanisms
Page 162 and 163: gen recovery rates in relation to p
Page 164 and 165: 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 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 218 and 219: twice the yield is necessary. We ha
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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