Use of Legumes for Maintenance of Rice Yield in Lowland Rice-Based Cropping Systems in Nigeria

A field experiment was conducted during the 2002 and 2003 cropping at Badeggi lowland to determine the effect of pre-rice planting of cowpea, mucuna, and cassava on the yield of rice crop. Cowpea and mucuna produced a mean biomass of 1.27 and 2.15 t/ha, respectively. The mean grain yield of cowpea was 825.5 kg/ha, while cassava yielded 4.0 t/ha. In the first year of the experiment, pre-rice legumes and N-fertilizer significantly affected grain yield and panicle/m2. The highest grain yield was obtained when rice was grown after cowpea with application of 30 kg/ha to rice. In the second year, only the plant height was significantly affected by pre-rice cropping and N-fertilizer application. However, rice yield obtained after cropping of cassava with N-application of 90 kg/ha to rice was higher than the yield obtained on rice grown after legumes. Economic analysis showed a positive economic benefit across the different rice production systems, although the marginal rates of return were higher when r...