The amount of fertilizer is increasing, but crop problems are also increasing: dead seedlings, rotten roots, yellow leaves and fallen leaves, soil hardening Why do crops suffer from malnutrition when so much fertilizer is used?

1. It is related to soil types: different soils have different fertilizer retention capacity. For example, clay has better fertilizer retention capacity than sandy soil. Fertilization should be carried out according to local conditions for different soils. For sandy soil and other soils with poor fertilizer retention capacity, small amount of fertilizer should be applied many times.

2. It is related to soil pH (PH): soil pH will directly affect the release of nutrients. Generally, in acidic soil, the utilization rate of nitrogen, phosphorus and potassium is low, the utilization rate of calcium, magnesium and sulfur is extremely low, and the utilization rate of trace elements boron, zinc and molybdenum is reduced; in alkaline soil, the utilization rate of phosphorus, iron, manganese, zinc and copper is also greatly reduced. The optimum pH value of soil nutrient release is 6-6.5, too much acid and too much alkali will affect the utilization rate of fertilizer.

3. It is related to the root system: the root system is the mouth of the crop, only the developed root system can improve the fertilizer absorption and utilization rate. For example, the absorption of phosphorus is only one tenth of that of nitrogen. In seedling stage, the root system is underdeveloped, and the nutrient absorption capacity is limited, especially the early growth promoting nutrients such as phosphorus and zinc.

4. Climate impact: in dry or rainy period, almost all nutrients in the soil are difficult to absorb; while in low temperature, phosphorus, magnesium, zinc, manganese and boron are not easy to be absorbed, resulting in the phenomenon of seedlings not growing, yellow leaves and small leaves.

5. Competition and antagonism between nutrients: excessive amount of one element in soil affects the release of other nutrients, resulting in nutrient imbalance. For example, too much potassium fertilizer will affect the absorption of boron and magnesium; too much phosphorus fertilizer will affect the absorption of potassium, copper, zinc and iron, so fertilization should pay attention to nutrition balance.

6. Nutrient deficiency is often invisible: many crops do not show visible symptoms of nutrient deficiency at the beginning, but it does not mean that nutrients are sufficient. It is too late to supplement nutrients when visible symptoms of nutrient deficiency are found. Therefore, we must balance fertilization and prevent in advance.