Ammonia emission patterns of typical planting systems in the middle and lower reaches of the Yangtze River and key technologies for ammonia emission reduction

Rice, vegetables, and fruit fields in the middle and lower reaches of the Yangtze River are the main sites of ammonia volatilization in the planting system of China. Therefore, there is an urgent need to understand the characteristics and key control technologies of ammonia emissions in the middle and lower reaches of the Yangtze River. This paper systematically reviewed the major progresses of the National Key Research and Development Project of the National 13^th Five-Year Plan: “Research and Development of Key Technologies for Efficient Ammonia Control and Emission Reduction in Planting System in the Middle and Lower Reaches of the Yangtze River,” and foreseen the research focus during the 14^th Five-Year period. The main research results included the followings: 1) The ammonia emission coefficient and characteristics of typical rice, and vegetables and fruit trees fields were identified, indicating that the paddy field had the largest ammonia emission coefficient and variation, averaging 14.2%, followed by open-air vegetables (averaging 11.2%), and fruit fields (averaging 4.76%). 2) After verifying the whole process of ammonia emission reduction, “reduction, retrain, control, and immobilization”, we put forward technologies such as optimized nitrogen reduction technology in paddy fields, deep fertilizer applications for ammonia emission control technology in paddy fields, ammonia emission immobilization by periphyton technology in paddy fields, deep application of large-size granular fertilizer for fruit trees, and slow-release fertilizer for open-air vegetables. With these technologies, we achieved the goals of reducing ammonia volatilization. During the 14^th Five-Year Plan period, the long-term in-situ monitoring and simulation of ammonia volatilization should be strengthened, ammonia emission reduction technologies should be evaluated environmentally and economically, and simple and low-cost ammonia volatilization emission reduction technology should be developed.