CHEMICAL AND MICROBIOLOGICAL SOIL CHARACTERIZATION AND Brachiaria brizantha BIOMASS PRODUCTION, AT DIFFERENT SAMPLING PERIODS

Abstract

This study aimed to characterize the chemical and microbiological soil as microbial carbon biomass (MCB), released carbon dioxide (C-CO2), mycorrhizal colonization (COL), and Brachiaria brizantha dry matter production (DMP), at different sampling periods. The test areas were located in four farms on the São Paulo State, Brazil: São José da Barra (51°07'59,02";W and 20°25'24,82";S), Valência (51°07'10,38";W and 20°27' 59,96";S), Primavera (50°59'44,02";W and 20°31'17,42";S) and Gior (50°59'19,00";W and 20°31'25,31";S). The predominant soil was a eutrophic red-yellow podzolic, for the S. J. da Barra, Valência, and Primavera farms, and an alic red-yellow podzolic for the Gior farm. The highest values for MCB were found on Apr./2003, with no differences between areas; for released C-CO2, highest values were showed on Aug./2002, at S. J. da Barra; highest DMP values were found on Aug./2002, at the Primavera; the highest COL values were obtained in Jul./2003, and the highest spore numbers were counted on Apr./2003, both in the S. J. da Barra. Despite the acid soil condition in all farms, as well as low nutrient content and moderate organic matter levels, the values for microbiological variables and DMP ranges from satisfactory to highly satisfactory. However, considering the areas histories, the necessity of chemical management in those areas is evident.

KEY-WORDS: Arbuscular micorrhyzal fungi; microbial biomass carbon; released C-CO2.carbon; released C-CO2.