Abstract
The unreasonable agricultural management measure is the main cause of the risk of nitrogen and phosphorus losses. The objective of this paper was to evaluate the impacts of agricultural management practices on the risk of nitrogen and phosphorus losses at catchment scales based on GIS and integrated index models. The results showed that 93.1% of the catchment was no risk and low risk area, while 6.9% for medium and high risk of nitrogen and phosphorus losses. Spatial analysis of risk index indicated that different agricultural management practices lead to number and proportion of grids are different. At very high risk area, about 599 of grid number is only for the actual management practice, accounting for 0.22% of the total, while at very low risk area, 165884.00 and 60.51% for river buffer zone respectively. Control effect of different agricultural management practices for risk of nitrogen and phosphorus losses is better, which very low and low risk areas of based fertilizer applied deeply and buffer zone construction accounted for 98% and 95.6%, and the control effect sorted as follows: base fertilizer applied deeply> construction of river buffer zone> reduced nitrogen application> reduced phosphorus application.
Highlights
Non-point source pollution caused by nitrogen and phosphorus losses is the main cause of eutrophication in water bodies
The grid analysis shows that the different agricultural management practices lead to different risk index and number and proportion of grids are different, respectively. (Fig. 3, 4)
The integrated index models were used to evaluate risk of nitrogen and phosphorus losses at Dongzhuang catchment, northeast Beijing of China, explore impacts of agricultural management practices on the risk of nitrogen and phosphorus losses based on GIS and index models, so as to provide more reasonable reference for controlling strategy of nitrogen and phosphorus losses risk
Summary
Non-point source pollution caused by nitrogen and phosphorus losses is the main cause of eutrophication in water bodies. Identification of the critical source areas (CSA) of nutrient loss is essential to improve management efficiency, reduce cost and targeted regulation of control strategies [13]. Nitrogen and phosphorus losses process is a complex process of non-point source pollution, which including topography, soil, climate, surface runoff, land use types, planting management, nutrient transport characteristics and varies both temporally and spatially [4,5,6]. Considered separately, nitrogen or phosphorus losses in any one party has not been sufficient to control eutrophication problem brought by the nutrient loss, and due to the differences between the biological, chemical and migration process for nitrogen and phosphorus in the soil, single targeted governance does not achieve the overall goal of improving water quality [7,8,9,10]. The results will provide a reasonable basis to control strategy of nitrogen and phosphorus losses for the catchment scales
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