C, N AND P STOCKS AND FLUX THROUGH THE MICROBIAL BIOMASS UNDER DIFFERENT SOIL MANAGEMENT

Resumo

Abstract - The objective of this study was to determine the effects of different crop systems on soil microbial properties and C, N and P stock after 22 years of cropping on an Oxisol (Typic Haplorthox) at Londrina, Brazil. Soil samples were taken at 0-5, 5-10 and 10-20 cm depths and evaluated for microbial biomass C, N and P. The cultivated sites presented lower microbial biomass and C and N stock than Forest site. While the total P stock presented under crop sites were higher than Forest site. The annual N and P flux through the soil microbial biomass means respectively about 65% and 45% for Coffee, about 50% and 70% for maize and 65% and 60% for wheat of the annual N e P needs. Those results evidence that the microbial biomass represents a substantial reserve of nutrients in the soil and may contribute substantially to the nutrients requirements of crops.