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IMPROVING SUSTAINABLE INTENSIFICATION OF CEREAL-GRAIN LEGUME CROPPING SYSTEMS IN THE SAVANNAHS OF WEST AFRICA: QUANTIFYING RESIDUAL EFFECTS OF LEGUMES ON MAIZE, ENHANCING P MOBILIZATION BY LEGUMES AND STUDYING LONG-TERM SOIL ORGANIC MATTER (SOM) DYNAMICS


Improved cereal-grain-legume systems, allowing farmers to use their land productively on a continuous basis, are being rapidly developed and adopted by small-scale farmers in the West African Moist Savannah. This paper summarizes work on several issues related to the improvement of productivity and sustainability of these intensified systems. A first study looked at the sustainability of several legume-maize cropping systems in a 5-year field trial at Sekou, Benin. Fairly low maize yields were found in continuous maize cropping systems (maize/maize), poor response to N fertilizer beyond 45 kg N ha~(-1), and no evidence that P and K were limiting crop yield. Over the last 5 years of the trial, maize/Mucuna relay cropping gave consistently a 2000 kg ha'1 yield increase relative to maize/maize cropping, and most of this yield gain was preserved even when Mucuna residues were removed from the plots when planting the next year's maize crop. Some yield gain, although far less than with maize/Mucuna, was observed in the maize/pigeon pea system. The maize/cowpea system offered no maize yield gain over maize/maize cropping. In a second study, enhanced isotopic methods to determine the plant available P allowed us to test the hypothesis that certain legume accessions can mobilize sparingly-available P. In one out of the 3 West-African Moist Savanna soils studied, we found that cowpea could access sparingly soluble soil P that is unavailable to maize. This mobilization of P was only observed when P deficiency occurred. These results confirm the P efficiency of some legume genotypes, which may lead to benefits of improved P availability by the incorporation of legumes in rotation systems. A third study, involving a 16-year continuous-cropping field experiment in lbadan, Nigeria, provided information on long-term changes in soil organic matter carbon (SOC) contents in savannah soils with sandy top soil. In the control treatments with continuous maize and cowpea cropping without trees, SOC levels dropped from the initial 15.4 Mg C ha~(-1) to 7.3-8.0 Mg C ha~(-1) in 16 years (SOC content in 1700 Mg ha~(-1) equivalent soil mass). In the two continuously cropped alley cropping systems (Leucaena and Senna), the SOC levels dropped to levels between 10.7 andrn13.2 Mg C ha~(-1). The ~(13)C natural abundance technique yielded useful information to test the ROTHC-rn26.3 SOC model in sub-humid tropical conditions under a complex pattern of cropping systems.......

【作者名称】: J. DIELS, G. DERCON, P. PYPERS, L. VAN LOON, R. MERCKX, K. AIHOU
【作者单位】: International Institute of Tropical Agriculture (IITA), Ibadan, Nigeria
【关 键 词】: IMPROVING SUSTAINABLE INTENSIFICATION OF CEREAL-GRAIN LEGUME CROPPING SYSTEMS IN THE SAVANNAHS OF WEST AFRICA: QUANTIFYING RESIDUAL EFFECTS OF LEGUMES ON MAIZE, ENHANCING P MOBILIZATION BY LEGUMES AND STUDYING LONG-TERM SOIL ORGANIC MATTER (SOM) DYNAMICS
【会议名称】: STI/PUB/1285; Consultants Meeting on Management Practices for Improving Sustainable Crop Production in Tropical Acid Soils; [19990501-03]; [Vienna(AT)]
【期刊论文数据库】: [DBS_Articles_01]
【期刊论文编号】: 101,065,231
【摘要长度】: 2,477
【会议地点】: [Vienna(AT)]
【会议组织】: International Institute of Tropical Agriculture (IITA), Ibadan, Nigeria
【会议时间】: 1999
【上篇论文】: 外文会议 - UAV remote sensing for phenotyping drought tolerance in peanuts
【下篇论文】: 外文会议 - Anticancer Potential of Compounds from an Edible Mushroom, Lentinus tuberregium (Fr. ) Fr.

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