The Effect Of Reducing Nitrogen Fertilization Combined With Enhanced Efficiency Nitrogen Fertilizer On Ammonia Volatilization And Nitrogen Use Efficiency In The Wheat-Maize Rotation Area Of Northern Henan Province

Ammonia（NH₃）is an agricultural non-point source pollutant that needs to be taken seriously,is responsible for the formation of haze and has many negative impacts on ecosystem function.In agricultural production,the heavy application of nitrogen fertilizer is the main trigger for ammonia emissions from farmland.However,in recent years,China’s successive bumper grain harvests have been largely associated with the heavy input of nitrogen fertilizer.As ammonia emissions in China have been high,ammonia emission reduction has become an increasingly urgent need for our atmospheric management.Therefore,we must meet the dual challenges of"China’s rice bowl"and"green water and green mountains".The North China Plain is a hotspot for ammonia emissions in China,and Xinxiang is located in the northern part of Henan Province,which is part of the North China Plain and is also a major grain producing area for maize and wheat in China.In this study,we investigated whether reducing fertilizer application and using new urea had a positive impact on ammonia reduction,crop yield and nitrogen use efficiency in farmland by studying the crop rotation system of winter wheat and summer maize in northern Henan with the objective of"fertilizer loss and efficiency increase,green development".The main findings are as follows:（1）Ammonia volatilization was measured in situ on farmland with different treatments using the Dr?ger ammonia tube method（DTM）.It was found that the maize season is the key period of the year for ammonia volatilization,that ammonia volatilization from surface spread N fertilizer was much higher than from application into deeper soil layers,and that changes in climate,soil and other environmental changes in different years caused different ammonia volatilization characteristics.In both maize seasons,ammonia volatilization losses as a proportion of applied N ranged from 2.3%to 4.5%for each treatment if N fertilizer was applied deep into the soil,and from 13.2%to 21.6%if N fertilizer was surface spread.In addition,180kg N ha^-1 of new urea with urease inhibitors reduced ammonia volatilization by 56.4%to 59.7%if nitrogen fertilizer was applied deep into the soil,and by 49.1%to 57.4%if nitrogen fertilizer was surface spread.Therefore,both the reduction of fertilizer application and the use of urease inhibitors are effective means of reducing ammonia volatilization.（2）Compared to 240 kg N ha^-1 common urea,fertilization with 180 kg N ha^-1 common urea only slightly reduced maize and wheat yields,while application of 180 kg N ha^-1 new urea hardly reduced or even increased yields,as in this study,application of the new loss-control urea increased total maize yields in two seasons,while the new humic urea increased total wheat yields in two seasons.Compared to 180 kg N ha^-1of common urea,all three new urea types increased total maize and wheat yields by 1.7%to 14.9%.（3）All three new urea types had a good stabilizing and improving effect on Nitrogen partial factor productivity（NPFP）,Nitrogen agronomic efficiency（NAE）and Nitrogen use efficiency（NUE）.Compared to 180 kg N ha^-1 common urea,all three new urea types improved the NUE in all seasons.Compared to 240kg N ha^-1 common urea,all three new urea types also improved the apparent NUE in all seasons,except for the new loss-control urea in the 2022 wheat season.