Research On Control Of Agricultural Non-point Source Pollution By Optimized Fertilization

Agricultural non-point source pollution has become the main source of pollution in Chaohu Lake Basin,especially the application of chemical fertilization.The eutrophication of Chaohu lake makes the control of agricultural non-point source pollution very urgent.This paper based on the main production mode of wheat and rice rotation in Chaohu basin and different fertilization treatments were set up in order to explore the effective prevention and the control of agricultural non-point source pollution of fertilization program.7 treatments were established in the wheat season:1.No fertilization;2.Conventional fertilization;3.Optimization of reducing fertilization with organic fertilizer;4.Optimization of reducing fertilization with soil loose agent;5.Optimization of reducing fertilization with biochar soil improvement agent;6.Carbon-based fertilizer;7.Maintained fertilizer.5 treatments were established in the rice season:1.No fertilization;2.Conventional fertilization;3.Optimization of reducing fertilization;4.Loss-control fertilizer;5.Carbon based fertilizer.Nitrogen and phosphorus in runoff,emission of greenhouse gas fluxes,residue analysis of soil nutrient content,economic benefits of rice and wheat of different treatments were analyzed to choose a suitable cleaner production for Chaohu basin of wheat and rice crop rotation fertilization model and to provide data for control of agricultural non-point source pollution in Chaohu basin.The results showed:1.Fertilization could increase the runoff loss of nitrogen and phosphorus in rice and wheat field significantly.Relative to conventional treatment,optimizing fertilizer could reduce contents of nitrogen and phosphorus in runoff,which controlled the contents of nitrogen and phosphorus in runoff positively.2.In the wheat season,runoff loss of nitrogen was from 2.092 to 5.554 kg·hm^-2,the loss rate was from 1.785%to 2.333%,and the phosphorus loss was from 0.016 to 0.021kg·hm^-2,and the loss rate was from 0.018%to 0.022%.In the second rice season,runoff loss of nitrogen was from 4.315 to 15.338 kg·hm^-2,the loss rate was from 2.61%to 6.52%,the total phosphorus loss was from 0.145 to 0.280 kg·hm^-2,and the loss rate was from0.24%to 0.38%.The runoff loss of nitrogen and phosphorus occurred in the rice season mainly.3.Compared with conventional fertilization,reducing fertilizer could reduce the total amount of nitrogen and phosphorus runoff loss.In the wheat season,the rate of nitrogen reduction was from 11.72%to 30.11%,and the reduction rate of phosphorus was from6.50%to 23.74%.In the rice season,the rate of nitrogen reduction was from 4.36%to64.74%,and the rate of phosphorus reduction was from 9.02 to 48.30%,which suggest that reducing the amount of fertilization can control agricultural non-point source pollution effectively.4.Fertilization could increase the contents of nitrogen and phosphorus in soil.However,there was no significant difference of the nitrogen and phosphorus residuals in the harvest time of optimization of reducing fertilization and conventional fertilization.5.The reduction of fertilizer application could reduce the emission of greenhouse gases CH₄ and N₂O effectively,which had a certain contribution to mitigate the greenhouse effect.The CH₄ emissions mainly occurred in the rice season,N₂O emissions mainly occurred in the wheat season.6.Related the environmental effects and economic benefits,the"Retaining fertilizer"and"Carbon-based fertilizer"treatments can be used as a production model suitable for wheat and rice rotation and control agricultural non-point source pollution in Chaohu Basin effectively.