Reduce-Retain-Reuse-Restore Technology for Controlling the Agricultural Non-point Pollution in Countryside in China: Source Reduction Technology
Due to the high dispersion of pollution source,spatial and temporal uncertainty of pollution emissions,source reduction technology become very important for non-point pollution control.In this paper,based on the authors' existing work,the source reduction technology was summarized and classified in accordance with the technical principles.Source reduction of non-point pollution can be achieved by reducing the fertilizer uses or the discharges.Fertilizer reduction could be achieved by using nitrogen optimizing based on the target yield and N-yield responsive curves,site-specific N management,balanced fertilization,organic combined inorganic fertilization,control-released fertilizer,or altering the crop systems with legumes.To reduce the discharges from agricultural fields,water regimes should be optimized,such as integrated water and fertilizer technology for dry lands,water-saving irrigation for paddy field,and conservation tillage for sloping lands.The adoption of source reduction technology for non-point pollution control should according to the regional environment characteristics and local conditions,and take into account the crop yield and economic benefits simultaneously.The future development of source reduction technology should focused on the labor-saving and cost-saving,and towards the intelligent and mechanization.In order to realize the maximum pollution reduction,ecological retain technology and nutrients reuse technology should be assembled together with the resource reduction technology.