Jingjiang City, During The Rice-growing Non-point Source Nitrogen Pollution Load Calculation And Control Countermeasures

The study of Non- Point -Source (NFS) nitrogen contamination in our country is relatively underdeveloped. Especially, the watershed environmental problem associated with NFS nitrogen contamination in rural area is getting worse. Therefore it is of practical importance to enhance both basic science research and development of protection techniques on this.In this paper, based on Universal Soil Loss Equation (USLE) and local conditions in Jing j iang city with its climate, soil properties, vegetation, precipitation, topography and human activities, model parameters are determined, and the city annual amount of soil-erosion is then calculated. Specifically, the amount of soil-erosion during the period of paddy planting is derived as well as the induced nitrogen-contaminated amount in the absorbed state.A typical paddy species in Jingjiang city is traced through its growing period for its fertilization, precipitation, irrigation and evaporation. The mass of nitrogen contamination in the flowing path and field-water is continuously monitored. Data is then input to the model, and the depth of precipitation flowing path in this area is obtained as well as the amount of field irrigation and drainage . Finally, the dissolved nitrogen contamination amount is estimated for the paddy-growing period.To conclude, the nitrogen contamination of paddy planting is mainly from the loss of agricultural field nitrogen fertilizer. The secondary attribution is the soil erosion. The total amount of nitrogen contamination from paddy-planting could consist of 85% of the total amount of annual nitrogen contamination [in this area] . Based on this analysis, means is proposed to improve the efficiency of the nitrogen fertilizer use and reduce the rural non-point-source nitrogen contamination.