Chemically synthesized compound fertilizers refer to compound fertilizers made through chemical reactions or ammoniation granulation processes, and synthesized through obvious chemical reactions. Common types mainly include diammonium phosphate, monoammonium phosphate, nitrophosphate, potassium nitrate, and potassium dihydrogen phosphate. This type of compound fertilizer contains elements required by two or more crops, with high nutrient content. It can provide the nutrients needed by crops in a balanced and long-term manner, improving the yield increase effect of fertilization.