Potassium: crop potassium deficiency is easy to occur in acidic soil, sandy soil and some high-yield areas with more nitrogen fertilizer in southern China.

The main feature of potassium deficiency is usually that the old leaves or leaf edges turn yellow, then brown and burning. Brown spots or patches appear on the leaves, and with the aggravation of potassium deficiency, the whole leaves turn reddish brown or even dry, necrotic and fall off. Root damage is the most obvious, short and few, prone to premature aging and serious decay.

Because potassium is highly mobile in crops, it flows from mature leaves and stems to young tissues for redistribution and utilization. Therefore, it is not easy to find potassium deficiency in early crops, but it does not appear until the middle and late stages of crop growth and development.