Biochar modifies the thermodynamic parameters of soil enzyme activity in a tropical soil

Purpose: Temperature is a key determinant of soil microbial processes, including the decomposition of soil organic matter and nutrient cycling. There is an interest in obtaining information on how microbial processes will respond to global change and, in particular, warming. Biochar can modify soil biological properties, but there is a dearth of information about its influence on the temperature sensitivity of soil biological processes. This research question has important implications in relation to modeling land-atmosphere interactions in soils amended with biochar. Materials and methods: Enzyme activity was determined at 4, 18, 27, 37, 54, and 70 °C in a control soil and in a soil amended with biochar, in order to determine how biochar affects the temperature sensitivity of soil enzymes (CM-cellulase, β-glucosidase, β-glucosaminidase, phosphomonoesterase, and arylsulfatase). The activation energy (Ea) and the temperature coefficient (Q10) were calculated. Results and discussion: In general, the values of Ea and Q10 were slightly but significantly lower for the soil with biochar. The results obtained are significant for modeling the carbon cycle and nutrient cycles in biochar-amended soils. Conclusions: The lower values for Q10 obtained for biochar-amended soil might be indicative of soil enzymes being underestimated by current enzyme assay conditions in biochar-amended soils.