The microbial biomass and activity are biological indicators sensitive to environmental changes caused by agricultural use and can provide important information for the planning of adequate land use. The objective of this research was to evaluate the nutrient recycling, persistence, and biological attributes of sorghum straw in Oxisol as a function of soil management systems. The experiment was carried out at the Federal Rural University of Amazonia in randomized block design with 3 x 2 factorial and four replicates. Three sorghum hybrids and two soil management systems were the factors used to assess straw decomposition. In order to evaluate the biological attributes, a 2 x 2 factorial experiment with four replicates was carried out using two soil management systems and two sampling dates. Total organic carbon (TOC), carbon in the soil microbial biomass (C-SMB), C-SMB/TOC ratio, basal respiration and metabolic quotient (qCO2) were investigated. The Qualimax hybrid presented the highest C/N ratio (55) and longer straw persistence in soil after 120 days of management (35%). The highest TOC, C-SMB, C-SMB/TOC ratio, and basal respiration and the smallest qCO2 were observed during the rainy season and in the no-till system.
Microbial biomass; C/N ratio; Oxisol
