农业非点源污染控制中的最佳管理措施及其发展趋势

农业非点源污染是最主要的一类非点源污染，容易造成水体的富营养化，降低环境的质量，已经成为构成目前水质环境恶化的一大威胁。农业非点源污染具有随机性、广泛性等特点，因此对农业非点源污染的控制相对比较困难。最佳管理措施通过工程措施、耕种措施和管理措施共同作用控制农业非点源污染，可以取得良好的经济效益、社会效益和环境效益。其中工程措施有梯田与山边沟，草沟与植被过滤带、人工湿地、节水灌溉系统等，耕种措施有保护性耕作、等高线种植、合理轮作等，管理措施包括有害生物综合治理、综合肥力管理、农旧灌溉制度等。最后，本文还对最佳管理措施的发展趋势作了展望。

Using best management practices to control agricultural non-point source pollution

Agricultural non-point source (AGNPS) pollution in surface and ground water by nutrients and pesticides has been identified as a major problem since the 1960s. AGNPS is the most important non-point source pollution, which is a significant contributor to eutrophication in aquatic systems. It is more difficult to control AGNPS than point source pollution because of the difficulty and expense of identifying and controlling discharges from no-point sources. Best management practices (BMPs) have been used for AGNPS control for two decades, and they have been designed primarily to control soil erosion. However, BMPs have been widely used in AGNPS control at present. BMPs influence two stages of AGNPS process by reducing the transport and the amount of potentially transportable pollutants. BMPs are the comprehensive practices which integrate with structural practices, cultural practices and management practices. Structural practices include terraces, hillside ditches, grass waterways and vegetable filter strips, constructed wetlands, irrigation systems etc, and their impact is primarily to reduce run-off through increased infiltration. Cultural practices involve conservation tillage, contour cropping and crop rotation to protect the soil surface and reduce erosion. And management practices are consisted of integrated pest management, integrated fertility management and irrigation management, they primarily affect the source of a potential contaminant by increasing usage efficiency. The developing tendency and prospect of BMPs is also discussed.