Effect of crop vegetation type on nitrogen and phosphorus runoff losses from farmland in one rainstorm event

The laws and characteristics of nitrogen and phosphorus runoff losses from farmland surface for different crop vegetations in north part of the Huaihe River basin were analyzed according to the experimental data of each rainstorm event in flood season.The result shows that the runoff,soil erosion,nitrogen and phosphorus losses are significantly affected by crop vegetation type.The effect intensities for various crops is in the order of bare landcorncottonsoybean.The leaf area index is the main factor that makes the surface runoff and soil erosion of various crop vegetations significantly different.The factors affecting the losses of nitrogen and phosphorus are also closely related to the leaf area index and surface runoff.It is found that the dissolved nitrogen and dissolved phosphorus are the main forms of nitrogen and phosphorus losses for cotton and soybean,but the particulate nitrogen and dissolved phosphorus are the main forms of nitrogen and phosphorus losses for corn plot.Soybean and cotton plots reduce the surface losses of nitrogen and phosphorus.