Effect Of Controlled Release Nitrogen Fertilizer On Nitrogen Behavior And Rice Yield In Paddy Field

The excessive use of chemical fertilizer in agricultural production not only causes excessive waste of resources,but also aggravate agricultural non-point source pollution.Reducing nitrogen loss in paddy field is the main way to control agricultural non-point source pollution.Controlled release nitrogen fertilizers are environmentally friendly fertilizers that can control the release of nitrogen,thereby reducing nitrogen loss.In recent years,many scholars have studied the effects of controlled release of nitrogen on rice yield and runoff leakage loss in rice fields.However,there have been few studies on the application of controlled release nitrogen fertilizer to surface water,runoff water and soil solution in paddy field.Therefore,the study of applying controlled release nitrogen fertilizer to reduce nitrogen loss and rice yield is very important for rice planting and water environment protection.There are six treatments conducted in this study.They are no nitrogen fertilizer?WN?,routine use of urea?CF?,controlled release nitrogen fertilizer(N₁₀₀),90%nitrogen of controlled release nitrogen fertilizer(N₉₀),80%nitrogen of controlled release nitrogen fertilizer(N₈₀)and 70%nitrogen of controlled release nitrogen fertilizer(N₇₀),respectively.Location experiments were carried out in paddy field,and the nitrogen content of each form in surface water,runoff water and soil solution was dynamically monitored.In order to explore the best application amount of controlled release nitrogen fertilizer from the point of both economy and environment and provide basis for cleaner production,the effect of controlled release nitrogen fertilizer on nitrogen content in surface water,runoff water and soil solution of rice field and the yield of rice in rice field were studied.Research results as follows:1.Application of controlled release nitrogen fertilizer can reduce the production of various forms of nitrogen in surface water.The highest concentration of nitrogen was observed in CF treatment,and the nitrogen concentration in the rest of the treatments decreased with the decrease of nitrogen fertilizer application.The nitrogen of various forms in surface water peaked between 1 and 4d after fertilization.The peak of nitrogen concentration in different fertilizer treatments of surface water appeared earlier than that of WN treatment.Ten days after fertilization is the key period to prevent the loss of nitrogen in surface water.2.Application of controlled release nitrogen fertilizer can significantly reduce the nitrogen concentration of runoff water.Total nitrogen concentration,average runoff and total runoff of each treatment were the highest and lowest in CF treatment and WN treatment.Compared with CF treatment,the total nitrogen concentration of early and late rice controlled release nitrogen fertilizer treatment decreased by 1.8%and 19.4%respectively.Compared with CF treatment,the average total nitrogen runoff loss of early and late rice controlled release nitrogen fertilizer treatment decreased by 7.93%and 24.8%respectively.The highest proportion of organic nitrogen and the lowest proportion of inorganic nitrogen in total runoff.3.Application of controlled nitrogen release fertilizer can reduce the nitrogen concentration in soil solution at different depths in rice fields.Nitrogen concentration of soil solution in each treatment were the highest and lowest in CF treatment and WN treatment.The concentration of total nitrogen,ammonium nitrogen and nitrate nitrogen in soil solutions of different soil layers decreased with the increase of rice growth time.The concentration of total nitrogen and ammonium nitrogen decreased with the increase of soil depth.The concentration of nitrate nitrogen and ammonium nitrogen showed an obvious trend,and its concentration increased with the increase of depth.4.The application of controlled release of nitrogen fertilizer under certain nitrogen content can achieve the highest yield of rice,and the risk of nitrogen loss in water is relatively low.When the theoretical nitrogen application was 68%to 81%of the controlled nitrogen release fertilizer,the maximum yield of rice reached 6099⁷104 kg/hm²,and the total nitrogen concentration in surface water,runoff water and soil solution was relatively low.The appropriate nitrogen release rate of controlled release nitrogen can achieve the desired environmental and economic benefits.To sum up,the application of controlled nitrogen fertilizer can achieve the benefits ofstable yield and nitrogen reduction.At the same time,it can reduce the nitrogen concentration,nitrogen runoff and leaching loss.To realize the win-win situation between the economic benefits and environmental benefits of rice.