Foliar fertilizer, also known as external fertilization, is a kind of organic or inorganic aqueous solution that is non-toxic, harmless and contains various nutrients, sprayed on the foliage of crops at a certain dose and concentration, directly or indirectly. The role of the ground to supply nutrients. Foliar fertilization is an effective way for crops to absorb nutrients and has become one of the important high-yield cultivation management measures. Compared with soil fertilizer, foliar fertilization has the characteristics of fast nutrient absorption, low dosage, high nutrient utilization rate and light soil pollution. Especially in the late stage of crop growth, root activity is reduced, and the ability to absorb fertilizer is reduced; or under stress conditions, such as soil drought and low nutrient availability, nutrients can be replenished in time through foliar fertilization. In addition, foliar fertilization can improve the quality of agricultural products. For example, the calcium content in apple fruit is an important factor affecting fruit quality. By directly spraying calcium nutrient solution on fruit, it has a good effect on preventing physiological calcium deficiency, increasing fruit firmness and prolonging storage time.
During the growth and development of crops, due to the content of trace elements in the soil and the sensitivity of different crops to micronutrient nutrition, it is often necessary to spray fertilizer containing trace element nutrients. Foliar fertilization can supplement plant nutrient solution by foliar spray, which can regulate plant growth, supplement missing elements, prevent premature aging and increase yield. Foliar fertilization can directly and directly supply nutrients, avoiding the adsorption and fixation of nutrients by the soil, improving the utilization rate of fertilizers; the dosage is small, suitable for the application of micro-fertilizer, and the yield increasing effect is remarkable. Crops require a small amount of micronutrients. In the case where the trace elements in the soil are not severely deficient, foliar fertilization can meet the needs of the crop. However, the crop requires a large amount of nitrogen, phosphorus, potassium and other large elements, and the foliar application value can only provide a small amount of nutrients, which cannot meet the demand of the crop. Therefore, the amount of nutrients needed to meet crops should be based on root fertilization, and foliar fertilization can only be used as an auxiliary measure.
The fertilizer used for foliar fertilization is called foliar fertilizer, referred to as foliar fertilizer.