Nitrogen mineralization and denitrification in bamboo riparian systems in Southeastern China
南方丘陵地区竹林河岸系统的氮矿化、反硝化作用研究

In situ nitrogen mineralization and denitrification rates in top soils are measured using soil core incubation methods and acetylene inhibition technique within a bamboo riparian system in Southeastern China. The results show that the net nitrogen mineralization rate ranges from -0.28 to 0.30 mg·kg-1·d-1, and has an obvious positive correlation with soil moisture (p<0.05). The peak nitrogen mineralization rate occurs in the zones adjacent to the river. The soil ammonification and nitrification rates vary from -0.43 to 0.35 mg·kg-1·d-1 and from -0.32 to 0.61 mg·kg-1·d-1, respectively. Continuous incubations indicate that nitrification in surface soils could contribute as much as 24% to 80% of nitrate nitrogen content, accounting for 56% (in average) of the final nitrate nitrogen content of the soil. Denitrification rate ranges from 0.03 to 3.88 mg·m-2·d-1, with high spatial and temporal variation. In addition, the peak denitrification rate happens in riverfront zones. As a result, stronger biogeochemistry processes are observed in the riparian zone adjacent to the river than those in the middle or cultivated field front, and nitrification and denitrification processes within the zone are closely coupled.