Effect of Plant Residues on the Size of Microbial Biomass and Nitrogen Mineralization in Soil: Incorporation of Cowpea and Wheat Straw

Abstract

In an incubation study, soil was amended with cereal (wheat) and legume (cowpea) plant materials. The amount of biomass C, biomass N and mineral N (NH4 and NO3) was estimated at 10, 20, 45, and 100 d after preincubation (30 d). The amount of biomass C was found to be largest in wheat straw-treated soils. No significant changes occurred in the C: N ratios of biomass associated with the incubation for 100 d of the soil with two plant materials but the ratios were higher in the wheat straw-treated soil than in the control and cowpea straw incorporation. The amount of mineral N and biomass N was significantly larger in the cowpea straw amended soil as compared to wheat incorporation. The sum of the mineral (initial) N amount in soil and that mineralized during incubation of a fumigated soil (flush N) may be a suitable index of available N status in a soil. © 1992, Japanese Society of Soil Science and Plant Nutrition. All rights reserved.