春季解冻期棕壤坡面磷素迁移过程研究

春季解冻期土壤季节性冻融发生最为强烈，极易发生土壤侵蚀，也是磷素流失的关键时期。采用人工模拟降雨的方法，探究春季解冻期不同磷素背景值坡面产流产沙及磷素流失动态过程。结果表明:产流后14 min内径流量和泥沙量均呈现较好的线性分布，径流相关系数为0.969，泥沙相关系数为0.936；14~18 min内径流量缓慢增加，从18 min开始一直到产流结束径流量基本保持在3 100 ml/min，而泥沙则总体呈现先增大再减小的趋势；土壤背景值（APb）越高，径流、泥沙中磷浓度越高；径流中磷素流失比率均值APb₂₀坡面最大，且随着背景值的增大呈减小趋势；而泥沙中磷素流失比率均值变化则与径流不同，APb₄₀的坡面其流失比率最小，其他坡面差异较小；径流中磷素流失量与泥沙中磷素流失量呈线性关系，y=6.751x-0.628（R²=0.958）。

Process of Phosphorus Loss in the Spring Thaw Period on Brown Soil Slope

Freeze-thaw is intense in the spring thaw period, soil erosion and phosphorus migration always happen frequently. In this study, rainfall simulation experiment was carried out on the slopes with different phosphorus (P) background values during the spring thaw period to study the dynamic processes of runoff, sediment yield and loss of P. The results showed that in the first 14 min, runoff and sediment presented the good linear distribution, the coefficients of correlation of runoff and sediment yield were 0.969 and 0.936, respectively, and then increased slowly in 14~18 min, runoff maintained its quantity of 3 100 ml/min until the end, while sediment yield generally increased first and then decreased. The higher soil background values are (APb), the higher concentrations of P are in the runoff and sediment; the average ratio of P loss of the APb₂₀ slope was the largest in runoff, and showed a decrease trend with the increase of APb value; while the average rate of P loss of APb₄₀ slope was minimum, and there were little differences between other slopes; P in runoff and sediment had good linear relationship, and the fitting equation is y=6.751x-0.628 (R² =0.958).