One-Time Deep Application of Nitrogen Fertilizer: A Potential Measure of Ammonia Mitigation in Grainland

Ammonia (NH3) is one of the main precursors of secondary inorganic aerosols. In 2018, the NH3 emissions of China's cereal production (rice, wheat and maize) were estimated to be 3.3 Mt NH3-N. Numerous NH3 mitigation strategies have been developed in agriculture to reduce the emissions and improve air quality. However, due to the cost and unfeasibility of some developed techniques, the application of these mitigation measures is relatively slow in cropland. Therefore, developing low-cost, easy-operation, and feasible mitigation measures is an important breakthrough to solve the pollution of ammonia emissions in grain fields. The one-time deep application of nitrogen fertilizer in crop growing season, referred to as one-time application, is a promising ammonia mitigation measure for grain fields. It is a low-cost mode of fertilizer application suitable for grain fields as it saves labor and reduces the input of agricultural machinery. Therefore, incentive policies should be formulated to promote it for wide-range application in the whole country, especially in the areas with serious ammonia pollution, in order to achieve the goal of green and sustainable agricultural production.