Spatial variability of nitrogen in soils from land/inland water ecotones

The variability of nitrogen (N) in soils from land/inland water ecotones, of Yueliangpao wetland was studied in the horizontal and vertical directions. Nitrogen concentrations in topsoils vary obviously with soil moisture gradient, decreasing from water body to hillock, and the variability is higher compared with subsurface soils (except for NH4+-N). Spatial variability of N in subsurface soils is significantly controlled by N form. For example, the changing tendency of NH4+-N concentrations is opposite to that in topsoils; NO3--N concentrations gradually decrease from the center zone to both sides; and the variability of K-N, OR-N, and TN is not only similar, but consistent in both soil layers. The surfacial variability of NO3--N in soils is highest due to leaching loss and denitrification; but that of NH4+-N is lowest, since is easily adsorbed by soil colloids, and difficult to be leached. Similar to-vertical variability, the surfacial variability, and distribution patterns of K-N, OR-N, and TN; and nitrogen concentrations in soils in this region are significantly correlated with SOM, TP, sand and clay content, but hardly influenced by soil pH values and silt content.