The Effect Of Nitrogen Application Rate On Ammonia Volatilization?the Study Of Nitrogen Fertilizer Threshold In Paddy Field

Ammonia?NH₃?is a kind of important trace gases,which have an important influence on atmospheric environment and the surface ecosystem.NH₃ can be intensified by atmospheric wet deposition in the surface water body causing eutrophication and non-point source pollution,such as generatted N₂O and increased the content of greenhouse gases in the atmosphere,and NH₃ is also an important prerequisite of the formation of aerosol haze pollution.Further more,paddy ammonia volatilization losses occupies an important proportion of total nitrogen loss,ammonia?NH₃?volatility is the main channel of nitrogen loss in paddy fields.So,studying the effect and mechanism of ammonia volatilization after the application of nitrogen is conducive to innovation of the key technology of control ammonia volatilization effectively.This study use the single harvesting field area in chaohu as the research object,set up five different gradient of N application levels,to adopt continuous airtight dynamic chamber method,studied the farmland under different N application rate of ammonia volatilization dynamic change,the influence of the amount of ammonia volatilization,ammonia volatilization factor,and explore the ammonia volatilization environment related nitrogen threshold.Test results show that:?1?The different levels of nitrogen fertilization increased risks of paddy ammonia volatilization.Different N application processing?0,168.75,225,281.75,337.5kg/hm²?dynamic show the similar rules of ammonia volatilization,1-3 days or 1-4days after fertilization to peak,and then reduce day by day,after 7-9 days tend to be no nitrogen treatment.Ammonia volatilization amount after three fertilizer is basal >tillering > spike.?2?The total ammonia volatilization increased with the increase of N application rate,different amount of N application,ammonia volatilization significant difference?P < 0.05?.Different nitrogen?N1-N4 interchange?amount of ammonia volatilization was 18.90 kg/hm²-95.77 kg/hm²,loss rate is 11.2% to 28.4%.The amount of ammonia volatilization,ammonia volatilization rate of optimized nitrogen?225 kg/hm²?is 33.79 kg/hm²-50.76 kg/hm² and 15.0% to 22.6%,respectively,in Chaohu area.?3?The main influence factors of ammonia volatilization in rice fields,chaohu lake region is N application rate,surface water of ?NH₄?⁺-N concentration,pH,temperature and rainfall,etc.Paddy NH₃ volatilization amount along with the increaseof N application rate increased significantly,exponential positive correlation;and the Surface water of ammonium nitrogen concentration and pH has significant linear positive correlation;Temperature rise will promote the ammonia volatilization,rainfall decreased the ammonia volatilization.Therefore,in terms of reducing the amount of ammonia volatilization,we need to control N application appropriately,reducing the surface water of ?NH₄?⁺-N concentration,keeping the surface water pH stability,Avoiding high temperature and less rain fertilization.?4?Based on the rice production safety,the economic efficiency and the volatilization multiple considering environmental safety,the ecological threshold of nitrogen we recommend is 168.75 kg/hm²-247.5 kg/hm² in single harvesting,chaohu area.