Abstract:Soil organic nitrogen mineralization is an important part of soil nitrogen cycle, and it is crucial for us to understand the soil organic nitrogen mineralization potential and advise the optimized fertilization. In this study, a short-term anaerobic incubation method at 35 ℃ was adopted to determine the soil nitrogen mineralization kinetics of five soils under different land use types in a typical hilly area of Jinjing town in Hunan province. We used a double first-order kinetic model (namely two-pool model) to fit the data of soil nitrogen mineralization kinetics. Then, the multivariate linear regression models for soil nitrogen mineralization kinetic parameters derived from two-pool model were developed based on basic soil properties. The results showed that the soil organic nitrogen was quickly mineralized in the early seven days and thereafter slowly, in particular for paddy soils. Two-pool models were fitted well to the soil nitrogen mineralization data. The soil nitrogen mineralization potentials (Nd) for different land use types were 85.9 mg/kg (vegetable land soil), 184.4 mg/kg (paddy field soil), 64.5 mg/kg (unused land soil), 37.0 mg/kg (woodland soil) and 11.4 mg/kg (tea field soil), and accounting for 5.77%、8.65%、4.42%、3.31%和1.25% of the total soil nitrogen, respectively. With regard to the mineralization rate constant (kd), the paddy field soil had the greatest value of 0.58/d, the woodland soil the lowest value of 0.07/d, and vegetable land soil (0.31/d), tea field soil(0.17/d) and unused land soil(0.15/d) in between. Both the fraction of soil total nitrogen in soil mineralization potential (fd) and kd were significantly related to soil total nitrogen, soil microbial biomass carbon(MBC), soil microbial biomass nitrogen, pH and carbon nitrogen ratio, respectively. The multiple linear regression models for predicting fd and kd were successfully developed by using MBC, TN and pH. We also found that MBC played a very important role in determining the kinetic parameters of soil organic nitrogen mineralization.