How to apply fertilizer efficiently

When applying chemical fertilizer to crops, attention must be paid to the acidity and alkalinity of chemical fertilizer if chemical fertilizer is to be applied efficiently. Chemical fertilizer can be divided into two kinds according to acidity and alkalinity: chemical acidity and physiological acidity.

Chemical fertilizer can be divided into two kinds according to acidity and alkalinity: chemical acidity and physiological acidity. Chemical acidity refers to the acidity and alkalinity of fertilizer dissolved in water. According to this, fertilizers can be divided into chemical acid fertilizers, chemical alkaline fertilizers and chemical neutral fertilizers. Ammonium sulfate, calcium superphosphate and other fertilizers that dissolve in water and present acidic or weak acidity are chemical acidic fertilizers; ammonia, potassium carbonate and other fertilizers that dissolve in water and present alkaline or weakly alkaline are chemical alkaline fertilizers; urea, potassium sulfate, calcium nitrate and other fertilizers that dissolve in water and present neutral or nearly neutral are chemical neutral fertilizers.

Physiological acidity and alkalinity refers to the acidity and alkalinity of soil after fertilizer is applied to soil and absorbed by crops. According to this, fertilizers can be classified into physiologically acidic fertilizers, alkaline fertilizers and neutral fertilizers. Ammonium sulfate is a commonly used nitrogen fertilizer. After application, ammonium ion and sulfate ion are generated in soil. Although these two ions can be absorbed by plants, the absorption of ammonium ion by plants is much greater than that of sulfate radical, so most sulfate radical remains in soil. Plants absorb ammonium ions and release hydrogen ions at the same time, making the soil acidic, so it is called physiological acid fertilizer. Sodium nitrate, calcium nitrate, etc. by the absorption of plants after the soil was alkaline, it is called physiological alkaline fertilizer. Ammonium bicarbonate and urea are neutral or nearly neutral after being absorbed by plants, and are called physiologically neutral fertilizers.

When purchasing and using chemical fertilizers, we must first understand the acidity and alkalinity of chemical fertilizers in order to apply them reasonably and improve fertilizer efficiency. Soil pH can not only directly affect the dissolution and precipitation of nutrients in soil, but also affect the activities of microorganisms, thus indirectly affecting the availability of soil nutrients. In acidic soils, soluble phosphorus tends to combine with iron and aluminum to form iron phosphate and aluminum phosphate, thereby reducing availability. Acid soils are also often deficient in sulfur and molybdenum. Therefore, acidic soil should choose alkaline or physiological alkaline fertilizers, such as calcium nitrate, ammonia water, ammonium bicarbonate, calcium magnesium phosphate, etc. In this way, it will not cause the soil to continue acidification, but also improve the activity of sulfur, molybdenum and other nutrients, otherwise it will reduce the availability of phosphorus fertilizer, resulting in the leaching of potassium, calcium, magnesium and other nutrients. However, in alkaline soil, especially calcareous soil, soluble phosphorus is easy to combine with calcium to form insoluble calcium phosphate salts, which will reduce the availability of phosphorus, and the availability of many trace elements such as boron, manganese, molybdenum, zinc and iron will also be greatly reduced, resulting in the shortage of these nutrients and various physiological diseases of crops. Therefore, in calcareous or alkaline soil, acid and physiological acid fertilizers such as calcium superphosphate, ammonium sulfate and ammonium chloride should be selected to improve soil acidity, so that phosphorus is not easy to combine with calcium to form insoluble calcium phosphate salts and reduce phosphorus availability, but also to improve boron, manganese, molybdenum, zinc, iron and copper availability. On the contrary, if acid fertilizer is applied to acid soil for a long time, it will make the soil acidified, hardened and infertile; on calcareous or alkaline soil, partial application of alkaline or physiological alkaline fertilizer will cause secondary salinization, structural deterioration and fertility degradation of soil.