Urea is a neutral quick-acting fertilizer with a chemical formula of CO(NH2)2 and a nitrogen content of up to 46%.  ‌‌Urea is a white crystal that is tasteless and odorless, easily soluble in water, ethanol and benzene, and slightly soluble in ether and chloroform.  The nitrogen content of urea is the highest among solid nitrogen fertilizers, which makes it a highly efficient nitrogen fertilizer. After application, no harmful substances will remain in the soil, and it has little destructive effect on the soil, so it is widely used. The application methods of urea include as a base fertilizer or topdressing.  Urea is decomposed into ammonium carbonate by microbial action in the soil, and ammonium carbonate is easily absorbed by plants, so urea has a rapid fertilizer effect. However, the utilization rate of urea is low, about only 20%-30%, and most of the urea applied to the soil will be lost or volatilized with water. In order to improve the utilization rate of urea, it can be carried out by deep application in advance or foliar spraying. The method of foliar spraying of urea is simple and effective, which can make urea quickly enter the leaves and participate in various metabolic processes of crops, significantly improving the utilization rate of urea.