Study On Control Agriculture Runoff Pollution

Agriculture non-point source pollution (ANPSP) has been one of the important pollution sources which influence the water quality of our country. This research is a part of Environmental Nonprofit Sector Research-Research system of sub-tropical agricultural pollution control technology(NO.200809093). Based on the research of the regular pattern of rainfall runoff, this thesis mainly researches the output mechanism of runoff pollution from farmland and the technology and method of preventing the pollution. The remainder of this paper is organized as follows.Section 1, which is the introduction, mainly introduces and reviews the status of ANPSP, the research status of rainfall pollution from farmland and the research progress of the way of curbing the pollution. Meanwhile, this section describes the purpose, significance and content of this research.Section 2 research the rainfall runoff of the specified area and the features of runoff pollution from farm. The result shows that the light rain is the major of this area, moderate rain and heavy rain may occur from time to time. The moderate rain and heavy rain in two hours is the typical rainfall. The variation of volume of runoff and the variation of consistency of runoff contaminant depend on the change of rainfall. There is a good relativity between the consistency of TN, TP, COD and the consistency of SS. The correlation coefficient is different because these elements exist in different form and different proportion.Section 3 presents the control effect of plastic mulching in runoff pollution of farmland. The result shows that:(1) plastic mulching enhances the volume of runoff. The increase is in inverse ratio to the water permeability of plastic film. Meanwhile, the more the rainfall is, the more the volume of runoff of farm is. (2) The plastic film obstructs the splash erosion of rainfall to the farmland and the erosion of runoff to the farmland. And the plastic film decease the consistency of contaminant in runoff except SS. In the farmland which is covered with plastic film, the drain of consistency of contaminant which is washed away except SS in farmland of high runoff is more than the consistency which in farmland of low runoff. The consistency of SS and the pattern of total quantity of drain are contrary to other pollution pattern. (3) The plastic mulching increases the drain of SS. To other contaminant, the plastic mulching decreases the drain of contaminant with runoff. Along with the increase of rainfall, the total quantity of runoff pollution which is washed away increase. The effect which plastic mulching impairs the drain of contaminant except SS is become obvious. The different effect which plastic mulching impairs the drain of COD, TN and TP is result from the different proportion in which the contaminant exists in diverse forms in the farmland. (4) Although the quantity which plastic mulching impairs the drain of COD, TN and TP is more than the quantity which straws mulching do, the total quantity is almost the same. Meanwhile the effect which straws mulching increase the harvest is better the effect which plastic mulching do. And the discarded plastic may cause secondary pollution. But the discarded straws can be the fertilizer which can increase the soil fertility without secondary pollution.Section 4 research the effect which the different way of interception control the runoff pollution of farmland. The research result shows that in the case of low rainfall and low runoff, the storage pond can intercept all the runoff pollution. In the case of high rainfall and high runoff, the storage pond will be filled. The runoff pollution will flow out. But the consistency of contaminant in runoff which flow out is low. The interception of farmland offer the field where the runoff pollution sediment naturally and dilute the runoff waste water. So the interception can impair the consistency of runoff pollution better. The runoff flows into the irrigated land. But whether this pollution will influence the crop development or not will be further research trend.Section 5 conclude and discuss this research work and propose the innovation of this thesis and the content which will be further studied.