Study On Runoff Loss Of Nitrogen And Phosphorus And Soil Properties After Long-term Reduction In Fertilization

For a long time,in order to increase crop yields,a large number of people have applied chemical fertilizers.Excessive chemical fertilizers have caused serious damage to the soil environment quality,and agricultural non-point source pollution has also become increasingly serious.In recent years,the problem of increasing agricultural non-point source pollution in the Chaohu Lake Basin has aroused widespread concern.Some scholars have also obtained some research results in the management of the Chaohu Lake Basin.However,there is a lack of reports on long-term reduction of fertilization location experiments.This study focused on the wasteful use of chemical fertilizers and straw in the Chaohu Lake Basin and used the six treatments in the long-term location of the Chaohu Lake basin: blank treatment,conventional treatment,optimized treatment,30% nitrogen reduction treatment,50%phosphorus reduction treatment and reduction.+ The straw was returned to the farm to analyze the yield and economic benefits of rice in the 10 th year(2017),nitrogen and phosphorus surface runoff and loss,crop nutrient uptake,fertilizer use efficiency,and soil nutrient traits.The characteristics of nitrogen and phosphorus runoff loss under reduced fertilization and the utilization rate of fertilizers under reduced fertilization and straw returning in the river basin were analyzed.Soil nutrient properties and enzyme activity after long-term reduced fertilization were analyzed.The main findings are as follows:(1)Long-term non-fertilizer treatment will significantly reduce crop yields,while reducing fertilization will reduce crop yields,but the effect of reduction will be insignificant.Analysis of crop economic benefits can yield net income plus reduction+ straw return treatment and optimized fertilization treatment.Higher,reduced nitrogen and phosphorus reduction net income is also higher than conventional fertilization,but lower than the reduction + straw returning and optimization of fertilization is low,reducing the amount of fertilizer + straw returned to the field is also the most effective.It can be seen that reduction + straw returning can increase yield and increase efficiency.(2)Reduced + straw return significantly reduced the loss of total nitrogen and total phosphorus,as well as the loss rate.Nitrogen reduction significantly reduced the total nitrogen loss and loss,and phosphorus reduction only significantly reduced the loss of total phosphorus.As a result,the loss rate was not significantly reduced or even had no effect.This may be due to the fact that the amount of loss was less than the reduction in fertilizer.(3)The reduced fertilization can increase the absorption of nitrogen and phosphorus in rice and wheat.In comparison with conventional treatment,the reduction in nitrogen absorption by N2 increased by an average of 2%,and the reduction in P increased by 6%.Field average increase of 38%,phosphorus absorption decreased by an average of 16%,phosphorus reduction increased by an average of 6%,reduction +straw return treatment increased by an average of 25%;rice season,compared to conventional fertilization,nitrogen absorption decreased Nitrogen treatment increased by an average of 14%,phosphorus reduction increased by an average of 17%,reduction + straw return increased by an average of 25%,phosphorus absorption decreased nitrogen treatment by an average of 12%,phosphorus reduction increased by an average of 15%,reduction + straw return The average increase of 25%.From the perspective of fertilizer utilization,nitrogen reduction has a significant effect on the improvement of nitrogen fertilizer utilization.Phosphorus reduction can increase the utilization rate of phosphate fertilizer.Reduction + straw returning can both increase the nitrogen fertilizer utilization rate and increase the phosphate fertilizer utilization rate.(4)Compared with the initial stage of the experiment,the reduction of straw content and returning straw to the soil resulted in an increase in organic matter,available potassium,and alkali-hydrolyzable nitrogen content in the soil in different degrees,resulting in a reduction in the available phosphorus content,and a decrease in available phosphorus content in soil.With 48% reduction,the effects of nitrogen and phosphorus reduction on the available potassium content in soil were not significant;for the content of alkali dissolved nitrogen,the nitrogen was reduced so as to reduce the effect of phosphorus reduction.The long-term reduction of nitrogen and phosphorus fertilizers has different effects on soil available copper,zinc,iron and manganese content.Nitrogen and phosphorus reduction will reduce the content of available copper and available iron in soil and increase the content of available zinc in soil.For effective manganese,phosphorus reduction will make With the increase,the reduction of nitrogen is reduced,and the reduction of + straw returning to soil will increase the content of effective copper,zinc,iron and manganese in the soil.The reduction of phosphorus and nitrogen fertilizers will reduce the activity of urease,neutral phosphatase and sucrase in soil to a certain extent.The reduction of + straw incorporation will not significantly increase urease,but it will significantly increase the neutral phosphatase and sucrase in soil.Activity.