人工降雨条件下黄土坡面养分随径流迁移试验

Laboratory experiments of soil nutrient transfer in the loess slope with surface runoff during simulated rainfall

降雨条件下坡面农用化合物随地表径流迁移既是农业问题，又是水环境问题。利用室内人工降雨模拟试验，研究了黄土坡面不同坡度下土壤氮、磷和钾随地表径流迁移的特征。研究结果表明，在定坡长土槽坡度变化为5°～25°范围内，初始产流时间随坡度增大呈先变小后增大的趋势；产流15min内，径流量均急剧增加，随后趋于稳定。随着坡度增加，水土流失程度加剧，径流溶质浓度增高，土壤侵蚀对径流溶质浓度的贡献增大。基于指数函数和幂函数拟合试验数据的结果，表明了幂函数模型更适合模拟黄土坡面非饱和条件下径流溶质浓度变化过程，也可描述径流磷和钾的流失过程，但其初始阶段的拟合不太令人满意。

The release and transfer of soil chemicals in surface runoff during the rainfall is not only an agricultural issue, but also a water environmental problem. The characteristics of soil nitrogen, phosphorus and potassium transfer with surface runoff were studied by simulated rainfall. Results indicated that, when the slope increased within the range from 5° to 25° for the given slope length, time to runoff commencement decreased first, and then increased with increasing slope. The magnitude of runoff first increased fiercely and then became stable within 15 min after the beginning of the runoff. Losses of soil and water became drastic and solute concentration in runoff enhanced with increasing slope, and the effect of the soil erosion on the solute concentration in runoff enhanced as well. Compared with the exponential function, the power function can be more suitable for fitting the changes of chemicals concentrations in runoff under unsaturated conditions from the loss slope, and for the description of the mass loss of phosphorus and potassium in runoff as well, but not for the initial phase. The study provided a reference for improving the model of soil nutrient transfer in runoff on the loess slope.