Study On The Ecological Environment Effect Of Controlled Release Fertilizer Application In Spring Maize In Black Soil Region Of Northeast China

The reports of the 19th National Congress of the Communist Party of China put forward the implementation of the strategy of rural revitalization and made comprehensive arrangements for the construction of rural ecological civilization.At present,the problems of unbalanced development in China highlight most obviously in rural areas.The rural environment and ecological problems are prominent,and the overall level of rural development needs to be improved?Central First Document,2018?.Farmland soil,an important part of agricultural ecology,belongs to the scope of sustainable utilization and ecological environment construction of natural resources forrural and regional development.However,modern agriculture has caused losses of organic matter and nutrients in farmland soil system by applying large quantities of chemical fertilizers,pesticides and mechanical power,which has reduced the productivity of farmland.China's environmental bulletin?2016?also pointed out that the overall quality of cultivated land in China is low,and there were prominent ecological problems such as imbalance of soil nutrients,declining fertility,environmental degradation,etc.The volatilization of farmland soil is an important source of N₂O emission in the world,and the volatilization of NH₃ is the main way of soil nitrogen gas loss.It is the dual demand of our country to ensure food security and agriculture to deal with global climate change to find out the regularity of N₂O emission and ammonia volatilization of farmland soil as well as to research the corresponding emission reduction measures.As a new type of fertilizer,controlled-release fertilizer?CRF?plays a positive role in improving resource utilization efficiency and reducing nitrogen loss.At present,the studies on controlled release fertilizer mainly focus on crop yield level and crop characters,but the characteristics of soil N₂O emission and ammonia volatilization under application of controlled release fertilizer are not clear.To address this unclear issue,we took spring maize planting model in Northeast China as an example and investigated the impacts of different fertilization treatments,including Farmer's conventional Practices?FP??180 kg N/hm²?,CRF180?180 kg N/hm²?,CRF144?144 kg N/hm²?,on soil N₂O emission and dynamic characteristics and total amount of ammonia volatilization by using static chanber-gas chromatography and Drager-Tube Method?DTM?.It provided scientific basis for environmental effect evaluation under controlled release fertilizer application.The main results were as follows:?1?The peak of N₂O emission in spring maize field in Northeast China mainly appeared after fertilization,lasting about 6 days and 13¹5 days after basal fertilization and topdressing,respectively.After basal fertilization,the peak value of N₂O emission flux after basal fertilizer application was 0.061mg·N·m^-2·h^-11 in customary fertilization treatment and 0.086 mg·N·m^-2·h^-11 in CRF.The N₂O emission flux of customary fertilization treatment was significantly higher than that of CRF treatment after topdressing.The peaks of ammonia volatilization were observed on the 1st²nd and 11th¹2th day following fertilization?including basal fertilization and topdressing?in corn growing season.The ammonia volatilization rate was gradually slower in the order of CRF180,FP,CRF144(1.00>0.93>0.92kg·hm^-2·d^-1),while the rate showed FP>CRF180>CRF144(2.61>2.39>2.34 kg·hm^-2·d^-1)after topdressing.?2?Soil temperature,moisture content and soil inorganic nitrogen content were the main environmental factors affecting N₂O emission and ammonia volatilization.There was a significant correlation?P<0.05?between soil temperatures well as moisture and N₂O emissions in CK treatment in the growing season of spring maize.The interaction of temperature,water,nitrogen and other factors masked its effect on N₂O emission and ammonia volatilization under fertilization conditions.Thus,no significant correlation between N₂O emission and ammonia volatilization was found in each treatment.?3?The application of controlled-release fertilizer could reduce N₂O emission.The treatment of CRF180 with the same amount of nitrogen fertilizer can reduce the total emission of N₂O by 19.21%.Yet under the condition of reducing 20%nitrogen application rate,the treatment of CRF144 could significantly?P<0.05?reduce the total N₂O emission of soil by 33.89%while keeping the crop yield.Ammonia volatilization represented CRF180>FP>CRF144.Iso-N controlled release urea did not decrease the total amount of ammonia volatilization in field soil when compared with ordinary graded fertilization,but increased.However,under the same nitrogen fertilizer but different nitrogen levels,the total amount of ammonia volatilization in the treatment with low nitrogen application rate was decreased by 17.65%.?4?Under the condition of this experiment,the controlled release fertilizer treatment could guarantee crop yield more than 12t hm^-1,and no significant difference was found between that and treatment FP?P>0.05?.The difference was significant that compared with treatment FP,CRF144improved agronomic efficiency of nitrogen fertilizer by 13%and partial productivity of that by17.47%?P<0.05?.Therefore,taking comprehensive consideration of N₂O emissions,ammonia volatilization,crop yield and nitrogen use efficiency,the practice of reducing 20%of the nitrogen application in combination with applying CRF was a suitable technology for increasing crop yield and reducing ammonia volatilization from spring maize fields in this area.