What are the methods of topdressing crops?

What are the methods of topdressing crops? Please introduce the methods of topdressing crops for reference as follows: 1 directly spread fertilizer between the rows of crops after watering or raining, while the soil moisture in the field is suitable and when you can go down to the field. Although this method is relatively simple, some fertilizers will volatilize, especially ammonium bicarbonate is very volatile and can not be used; ammonium sulfate, urea and potassium sulfate can be sprinkled, but it can only be selected when the field operation is not convenient and the crop needs fertilizer urgently. (2) when watering crops, fertilizers are applied to the soil around the crop roots with water. The disadvantage of this method is more waste, easy to lose, and can not reach the deep layer of the crop root system; the advantage is that it is simple to use, labor-saving and time-saving, and the amount of labor is not large. This method can be used when the fertilizer source is sufficient, the planting area is large, and the labor contradiction is prominent. When serious fertilizer deficiency occurs in a large area of crops, it can be used as the first choice for topdressing. (3) Deep-buried fertilization is used to dig trenches and holes between crop plants and rows, apply fertilizer, and then cover the soil. The use of this method is less fertilizer waste, the most economical, but large amount of labor, labor-consuming, and the operation is not very convenient. During application, it should be noted that the ditches and pits buried with fertilizer should be more than 10cm from the root and stem base of the crop. If it is too close to the root, it is easy to damage the root system. Due to the concentration of fertilizer and high concentration, this method is not suitable to be used in summer when crops grow vigorously and need more water, let alone in the critical period of crop water demand. Generally in the winter idle season, when the labor force is sufficient, and the crop growth is small, this method can be used to gradually decompose the fertilizer buried in the soil and supply the crops continuously. However, in actual production, the growth peak of crops is often the peak of fertilizer and water demand, so the burying method is often used when the temperature is high. In order to prevent its negative effect, it must be watered after burying application to reduce the concentration of buried fertilizer. (4) in recent years, with the development of protected cultivation technology, the corresponding drip irrigation technology has been widely used, which makes the fertilization method on the track of automation. The specific method of topdressing using drip irrigation facilities is to install a fertilizer applicator where the water source enters the drip irrigation pipe, dissolve the fertilizer in the fertilizer applicator, and insert the drip irrigation pipe into the suction pipe filter of the fertilizer applicator. with watering, the fertilizer can automatically enter the soil around the crop root system. Its advantage is that due to plastic film mulching, fertilizer is almost non-volatile, no loss, fertilizer is concentrated, but the concentration is small, so it is safe, labor-saving and labor-saving, and the effect is very good. At present, this is a more scientific topdressing method with great development prospects, but it is difficult to popularize and apply in large-scale production because of the large investment. 5 external topdressing is foliar spraying. In protected cultivation, because the man-made environment is more conducive to meet the requirements of crops for environmental conditions, crops show the characteristics of rapid growth, high yield and many fruits. In production, foliar topdressing is often combined with spraying to supplement the deficiency of crop nutrients. This method has the advantages of low dosage, fast fertilizer effect, and can prevent the effective components of fertilizer from being fixed by soil, so it is an economical and effective fertilization method. It can better show its effect when it is used in the case of obvious lack of nutrient elements and root senescence in the later stage of crop growth. In addition to a large number of element fertilizers commonly used, such as urea, potassium dihydrogen phosphate, potassium sulfate, potassium nitrate, compound fertilizer, etc., in recent years, many manufacturers have developed fertilizers suitable for foliar spraying of crops with a large number of elements plus trace elements or fertilizers containing a variety of amino acids, such as Fertilizer, Spencer, phytoprotegerin and so on. However, it must be noted that the basic nutrient elements needed for crop growth and development mainly come from base fertilizer and other fertilizers applied in other ways, and extra-root topdressing can only be used as an auxiliary measure. Click to get more compound fertilizer application techniques