Effect of Drainage Ditch Layout on Nitrogen Loss by Runoff from an Agricultural Watershed  

作　　者：ZHANG Zhan-Yu KONG Li-Li ZHU Lei R.M.MWIYA 

机构地区：[1]Key Laboratory of Efficient Irrigation-Drainage and Agricultural Soil-Water Environment in Southern China,Ministry of Education,Hohai University [2]College of Water Conservancy and Hydropower Engineering,Hohai University

出　　处：《Pedosphere》2013年第2期256-264,共9页土壤圈（英文版）

基　　金：Supported by the National Natural Science Foundation of China(No.50839002);the Doctoral Fund of Ministry of Education of China(No.200802940006);the Public Research Special Fund of Ministry of Agriculture of China(No.200903001-05)

摘　　要：A comparison experiment was performed, by designing one field ditch （D1 treatment）, two field ditches （D2 treatment）, three field ditches （D3 treatment）, and no field ditch （CK treatment）, in an upland of a small agricultural watershed in Nanjing-Zhenjiang hilly regions to observe the farmland surface runoff and N loss characteristics under the different layouts of field ditch. As the layout density of field ditch increased, the drainage effect was improved, the timing of the runoff peak was advanced, and also the peak flow was augmented. At the same time, both the concentration and accumulated transfer flux of total nitrogen （TN） were improved, and thereinto the accumulated transfer fluxes of TN under D3, D2 and D1 treatments were increased by 1.46, 1.34 and 1.16 times, respectively, than that under CK treatment. However, the accumulated transfer fluxes of nitrate-nitrogen （NO3-N） and ammonium-nitrogen （NH4＋-N） under D3, D2 and D1 treatments were reduced by 33.9%, 21.4% and 8.6%, and 35.8%, 24.7% and 12.2%, respectively, compared with those under CK treatment. Under CK treatment, the NO3-N and NH4＋-N concentrations were more sensitive to rainfall intensity than the TN concentration. There were significant linear relationships between the transfer fluxes of TN, NO3-N and NH^-N and the runoff flux, with the correlation coefficients of 0.942, 0.899 and 0.912, respectively. In addition, this correlation was also influenced by the layout density of field ditch. Therefore, the environmental effect should be taken into account when designing and constructing field ditches. Especially in the regions of severe fertilizer loss, the approaches of properly increasing the drainage area and decreasing the layout density of field ditch could be adopted under the precondition of avoiding crops from waterlogging.A comparison experiment was performed, by designing one field ditch (D1 treatment), two field ditches (D2 treatment), three field ditches (D3 treatment), and no field ditch (CK treatment), in an upland of a small agricultural watershed in Nanjing-Zhenjiang hilly regions to observe the farmland surface runoff and N loss characteristics under the different layouts of field ditch. As the layout density of field ditch increased, the drainage effect was improved, the timing of the runoff peak was advanced, and also the peak flow was augmented. At the same time, both the concentration and accumulated transfer flux of total nitrogen (TN) were improved, and thereinto the accumulated transfer fluxes of TN under D3, D2 and D1 treatments were increased by 1.46, 1.34 and 1.16 times, respectively, than that under CK treatment. However, the accumulated transfer fluxes of nitrate-nitrogen (NO3-N) and ammonium-nitrogen (NH+4 -N) under D3, D2 and D1 treatments were reduced by 33.9%, 21.4% and 8.6%, and 35.8%, 24.7% and 12.2%, respectively, compared with those under CK treatment. Under CK treatment, the NO3-N and NH+4-N concentrations were more sensitive to rainfall intensity than the TN concentration. There were significant linear relationships between the transfer fluxes of TN, NO3 -N and NH+4 -N and the runoff flux, with the correlation coefficients of 0.942, 0.899 and 0.912, respectively. In addition, this correlation was also influenced by the layout density of field ditch. Therefore, the environmental effect should be taken into account when designing and constructing field ditches. Especially in the regions of severe fertilizer loss, the approaches of properly increasing the drainage area and decreasing the layout density of field ditch could be adopted under the precondition of avoiding crops from waterlogging.

关 键 词：drainage velocity layout density of field ditches surface runoff transfer fluxes UPLANDS 

分 类 号：S277[农业科学—农业水土工程]