Catchment agriculture and local environment affecting the soil denitrification potential and nitrous oxide production of riparian zones in the Han River Basin, China
Abstract Riparian zones play an important role in reducing nitrogen (N) loading to rivers and streams primarily through soil denitrification which reduces nitrate (NO3 to nitrous oxide (N2O) and dinitrogen (N2) gases. Although the relationships between local environments and soil denitrification are well understood, relatively little is known about the indirect effects of landscape factors (e.g. catchment agriculture) on the soil denitrification of riparian zones. In this study, we used the acetylene block technique to measure the denitrification potential and net N2O production of soils collected from 62 riparian sites in 15 subtropical rivers of varying catchment land uses. The results indicated that, among the local factors studied, the soil moisture, organic matter and NO3 concentrations were positively associated with both the denitrification potential and N2O production rate. Agricultural riparian zones had a denitrification potential (2.81 1.01 ng N g 1 h 1) significantly higher than forested riparian zones (0.66 0.24 ng N g 1 h 1) Additionally, the riparian denitrification potential increased with the percentage of agriculture in the catchments (R 0.53, P