Development Of Localized Ammonia Emission Inventory For Field Fertilization In Northeast China

Ammonia volatilization from soil is an important way of nitrogen loss in farmland in China,and ammonia entering the atmosphere from soil may form secondary particles through secondary reaction with acid gas,leading to air pollution.It is of great significance to observe and understand the characteristics of ammonia volatilization from farmland soil and develop regional ammonia emission inventory for farmland nitrogen management and air pollution prevention and control.From May to October 2018,Field experiment for ammonia emission under different fertilization measures in Shenyang Agricultural University experimental site was developed,and the basal fertilizer using resin coating slow-release fertilizer,topdressing fertilizer using urea as the conventional fertilization.set up five treatment: no nitrogen treatment(T0),conventional fertilization by half(T1),conventional fertilization + biochar(T2)and conventional fertilization one-time application(T3),conventional fertilization(T4).Ammonia was collected by Phosphoric acid sponge-PVC pipe method,and the ammonia emission flux was detected by flow injection analyzer,and the change characteristics of soil related physical and chemical indexes were observed in the same period.The results showed that the ammonia volatilization rate showed a two-peak trend after applying base fertilizer.After applying top dressing fertilizer,each treatment reached the maximum ammonia volatilization rate on day 1 to 2.The accumulation of ammonia volatilization was shown as conventional fertilization + biochar(T2)>conventional fertilization(T4)>conventional fertilization one-time application(T3)>conventional fertilization by half(T1)>no nitrogen treatment(T0);There was no significant difference in soil ammonium nitrogen content between treatments in each period,but soil ammonium nitrogen content and soil ammonia volatilization rate in the same period showed similar change trend,and the change trend was more similar after topdressing than after basal dressing.There were significant differences in The accumulation of ammonia volatilization in the growing season between treatments.Conventional fertilization + biochar(T2)had the largest accumulation of ammonia volatilization.The ammonia volatilization was significantly reduced by using slow-release fertilizer without urea topdressing.Based on field experiment and questionnaire investigation,this study modified soil ammonia emission factors in the northeast China,and through the literature statistics obtained emission activity level data of the farmland in all counties in northeast China.Based on the localization emission factor,this study established the 2016 ammonia emission inventory of farmland in northeast China,and analyzed the ammonia emission characteristics of farmland soil fertilization in northeast China.The ammonia emission inventory study shows that in 2016,the ammonia emission from farmland fertilization in northeast China was 89.7 kt,including 68.4 kt from paddy fields and 21.2 kt from dry fields.Ammonia emissions from agriculture in northeast China are generally higher in central and southern than in northwest.The amount and intensity of ammonia emission in Liaohe Plain,Sanjiang Plain and Songnen Plain are higher than those in mountainous areas.Ammonia emission from farmland soil is a semi-man-made and semi-natural process with obvious regional characteristics and time variation.Therefore,the establishment of scientific farmland ammonia emission management measures first needs to accurately understand the characteristics of soil ammonia volatilization caused by the current application of farmland fertilizer in northeast China.This research mainly through the field experiment,questionnaire survey and statistics method,obtained localized ammonia emission factor based on the current actual conventional fertilization in the northeast China,and established an inventory of ammonia emissions from farmland in northeast China based on the activity levels of all counties in northeast China,Therefore,it provides an important scientific basis and data support for the assessment,management and air quality research of atmospheric ammonia emissions in this area.