TOTAL ORGANIC CARBON, MICROBIAL BIOMASS AND SOIL ENZYME ACTIVITY AREAS OF AGRICULTURE, FORESTRY AND GRASSLAND IN THE MIDDLE VALLEY OF PARAIBA DO SUL RIVER (RJ)

TOTAL ORGANIC CARBON, MICROBIAL BIOMASS AND SOIL ENZYME ACTIVITY AREAS OF AGRICULTURE, FORESTRY AND GRASSLAND IN THE MIDDLE VALLEY OF PARAIBA DO SUL RIVER (RJ) Soil characteristics such as total organic carbon (TOC), microbial biomass and enzymatic activity are influenced by many factors and have been suggested as suitable indicators of changes caused by different land use systems and soil management. The objective of this study was to evaluate the COT, microbial biomass and enzymatic activity of a typical Inceptisol in agricultural, forest and grassland areas in the Middle Valley of the Paraiba do Sul river (RJ). The systems evaluated were: annual agriculture (Agan); perennial agriculture (PAg), pasture, early secondary forest (SFEA) intermediate secondary forest (SFSM) in advanced succession stage (SFEA). Soil samples were collected from the 0-5 cm, layer in two different seasons (dry and rainy) to determine the total organic carbon (TOC) and biological properties (microbial biomass -CBM; microbial biomass N-NBM; basal respiration-RB; metabolic quotient - qCO2; microbial quotient - qMIC, and activity of the enzymes arylsulfatase, beta-glucosidase and acid phosphatase). The soil of the agricultural areas showed a reduction in the TOC and biological properties (enzyme activity and carbon and microbial biomass nitrogen) compared to pasture and forest. The principal component analysis distinguished the agricultural systems from the forest and pasture systems. It was observed that in both periods, the SFSM and pasture were associated with the COT and most biological factors, as opposed to the agricultural systems.