Assessing the influence of soil spatial variability on water leakage and dissolved organic nitrogen leaching through simulation
The processes of transportation and transformation of dissolved organic nitrogen(DON)in soil were simulated in this paper using the COMSOL software.The influence of spatial variability of soil initial state and soil hydraulic parameters on water leakage and DON leaching were investigated u-sing the local sensitivity analysis and global sensitivity analysis.The results indicated that the soil wa-ter leakage was positively correlated with soil initial matrix potential and the soil DON leaching was positively correlated with soil initial matrix potential and DON initial content.For the clay with a low spatial variability,the uncertainty of soil water leakage was mainly caused by the spatial variability of saturated water conductivity and saturated water content while it was mainly caused by the spatial vari-ability of saturated water conductivity when the spatial variability of soil reached a medium level.The DON leaching was more sensitive to the fluctuations of the saturated water conductivity at different de-grees of spatial variability.For large-scale coastal areas,the degree of water leakage and DON leaching was the same in most regions for the region with a low spatial variability while the spatial distribution of soil water leakage and the DON leaching would be more uneven.Substantial water and nitrogen leac-hing would occur in some areas for the region with a medium spatial variability.Considering the charac-teristics of soil spatial variation in water and nitrogen management is helpful to reduce the loss of soil nutrients and then reduce the risk of the DON leaching to groundwater.
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