The applied fertilizer can not only supply the nutrients needed by crops, but also improve the soil. For example, the application of lime to acidic soils can neutralize the acidity of the soil, reduce the toxic effects of iron and aluminum, and improve the effectiveness of soil nutrients. On the contrary, the application of gypsum and yellow repellent to the soil can chemically react with sodium and sodium bicarbonate in the soil surplus solution to generate soluble sodium sulfate, which can reduce the alkalinity of the soil in combination with irrigation and drainage measures.
Chemical fertilizers are mainly used to supply crop nutrients, and the fertilizer efficiency is fast, which plays an important role in improving crop yield, especially in low-yield fields caused by nutrient deficiency, the effect of applying chemical fertilizers is more obvious. In addition, after people take away the available part of the crop, a large number of roots, fallen leaves and orange sticks remaining in the soil can be returned to the field, which not only increases the organic matter in the soil, but also has a significant role in improving the soil environment and soil fertility.

While affirming the advantages of applying chemical fertilizers, it should also be pointed out that, unlike organic fertilizers, improper application is not only detrimental to the growth and development of crops, but also makes the soil acidic, alkaline or hardened. For example, the application of alkaline fertilizers such as sodium nitrate on alkaline soil can further alkalize the soil, while the long-term application of physiological acidic fertilizers such as ammonium chloride and ammonium sulfate on acidic soil will further alkalize the soil. There is also a long-term application of a single nutrient fertilizer, such as nitrogen fertilizer, will not only cause the disorder of nutrition in crops, resulting in reduced production, but also cause the imbalance of soil nutrient ratio, soil fertility decline or soil compacture. Therefore, reasonable fertilization must be the combined application of organic fertilizer and chemical fertilizer, and the combined application of nitrogen, phosphorus and potassium in chemical fertilizer, so as to learn from each other's strengths and make up for their weaknesses, which can not only supply effective nutrients to crops in time, but also improve the soil, improve fertility, and ensure the continuous high yield of crops.