Soil carbon and nitrogen mineralization after the initial flush of CO2

Abstract

Soil health evaluation with biological activity requires standardization for greater understanding across environments. Soil-test biological activity (STBA) may be an important indicator of soil N availability, but how it relates to long-term soil N mineralization (NMIN) has not been documented. This study evaluated short- and longer-term C and N mineralization in five soils from Georgia and North Carolina to validate associations between STBA and net NMIN. Although mathematical descriptions of cumulative C mineralization (CMIN) were logical and consistent among soil types, descriptions of net NMIN were complicated by the need to fit to single and double exponential models for different soil types. Rather than relying on exponential model fitting, emphasis on associations between linked processes of CMIN and NMIN resulted in simple, logical, and relatable interpretations. Soil-test biological activity is a simple, rapid, and robust indicator that shows strong association with soil NMIN for up to 150 d.