在农田施用厩肥或混合肥会增加径流中的P含量。 1993年Lemunyon等人提出了一个农地潜在磷污染评估指数。采用 3次模拟降雨研究的数据对与P指数相关的各变量进行了评估。研究小区种植的作物有高粱、玉米、冬小麦 ,施化肥、混合肥或来自养牛场的非混合肥 ,耕作措施采用免耕或圆盘耙耕。在计算指数时 ,考虑侵蚀、径流、土壤P水平、施P量及方法、以及P追加比例的影响。土壤侵蚀测量表明 ,由土壤侵蚀引起的全P和颗粒P流失量分别占其总流失量的 78%和 88% ,说明侵蚀在与沉积物有关的P流失中的重要性。生物有效P、溶解P的流失与侵蚀不相关 ,但与耕作、径流量、P源相关。利用各因子权重相加所得指数值比利用各因子权重相乘所得的指数值 ,与全P流失的相关性更紧密。如果能够精确地预测出侵蚀和径流 ,P指数可成为预测某一地域潜在输入地表水中P值的有用工具 Applying manure or compost to farmland increases the P content in runoff. In 1993, Lemunyon et al. Proposed a potential phosphorus pollution assessment index for agricultural land. Three variables associated with the P-index were evaluated using data from three simulated rainfall studies. Crops planted in the study area include sorghum, corn, winter wheat, chemical fertilizers, mixed fertilizers or non-compost from cattle farms. Tillage practices include tillage or disc harrowing. In calculating the index, we consider the effects of erosion, runoff, soil P level, amount and method of application of P, and additional proportion of P. Soil erosion measurements show that total P and particulate P losses due to soil erosion account for 78% and 88%, respectively, of their total loss, indicating the importance of erosion in sediment-related P losses. Biologically effective P, loss of dissolved P was not related to erosion, but was related to tillage, runoff and P source. The correlation between the index value obtained by the sum of the weight of each factor and the index multiplied by the weight of each factor is more closely related to the total P loss. The P-index can be a useful tool for predicting the potential P input into surface waters in a given area if erosion and runoff can be accurately predicted