Although potassium is a component of the tree unlike nitrogen and phosphorus, it participates in physiological and biochemical reactions such as nutrient synthesis, transformation and transportation, and enhances drought resistance. When applying nitrogen fertilizers, potassium fertilizers should be used together, which can promote the absorption and transformation of nitrogen by mulberry trees and synthesize protein, so that the mulberry trees can grow well, have full leaves and mature early, which is beneficial to improving the yield and quality of mulberry leaves; when nitrogen fertilizer is insufficient Applying more potassium fertilizer will cause premature aging of mulberry leaves; if the soil potassium deficiency in the mulberry garden is severe, symptoms will appear. Chlorosis spots will first appear on the old leaves at the base of the branches. In severe cases, the tips and edges of the mulberry leaves will turn yellow and wither. , the leaves fall off; since potassium is concentrated in the young organs of the mulberry tree, potassium deficiency develops upward from the old leaves. Sandy soils and acidic soils are prone to potassium deficiency.