The Soil Nitrogen at Different Flooding Gradient in the Riparian Zone of Three Gorges Reservoir Area

摘要

Nitrogen (N) in soil has great influence on soil quality and water quality, but the change in soil N at different flooding gradient has rarely been studied. The objective of this study was to determine the change in N in soil at different flooding gradient in the riparian zone of Three Gorges Reservoir Area. Permanently flooding site (below 145 m), seasonally flooding site (145-175 m), and never flooding of orchard garden (175-185 m, as a control) soil samples were collected from the Tongzhuang River and the Lanling River. The results showed that soil NH4+-N value increased gradually, whereas soil MBN, NO3--N decreased readily with flooding gradient. MBN/TN tended to be highest in seasonally flooding site. The results suggested that the highest accumulation of soil NH4+-N content, and lowest contents of MBN, and NO3-N was occurred under permanently flooding sites. Hydrology is a primary driving factor in the development of wetland soil N properties.