Why do yields increase only limitedly as more and more chemical fertilizer is applied

With the use of chemical fertilizers, grain yields have been greatly increased. However, after years of chemical fertilizer application, the input of organic fertilizer has decreased, resulting in soil compaction, a lack of trace elements and severe nutrient imbalance. Even if the amount of chemical fertilizer applied is increased, it is difficult to revive the vitality of the soil again.

So how to maintain the nutrient balance of the soil is the key.

1. Apply more organic fertilizer, grow green manure crops and apply chemical fertilizer rationally, so as to benefit not only the high yield of the current season's crops but also the restoration and improvement of soil fertility.

2. Long-term repeated cultivation of the land will cause soil fertility to decline, which in turn affects the growth and development of crops. Appropriately increasing the area planted with leguminous crops and growing one crop of legumes about every four years in the rotation can increase the nitrogen content in the soil. At the same time, after leguminous green manure crops are turned into the soil, their large amount of roots, stems and leaves can increase soil organic matter, improve the soil's physical and chemical properties and raise soil fertility.

3. After the crops are harvested, chop the straw and return it directly to the field. This can improve the physical properties of the soil, promote the formation of soil aggregates, increase air permeability, water permeability and fertilizer retention capacity, thereby improving soil fertility.