What should we pay attention to when topdressing crops?

What should we pay attention to when topdressing crops? Please introduce to crops foliar topdressing if you want to have a good effect, you should pay attention to the following points: first, the leaf wetting time should be as long as possible. After spraying outside the root, the longer the wetting time of the leaf, the more nutrients the plant absorbed. Therefore, it is better to spray after 4 o'clock in the afternoon or before 9 o'clock in the morning when applying fertilizer outside the root. The second is to let the solution fully adhere to the leaves. Fertilizer spraying must be meticulous, all parts of the plant should be sprayed evenly and finely. To use a sprayer with better performance, you can also mix a small amount of wetting agent or washing powder to promote the infiltration of nutrients into the leaves. The third is to pay attention to the appropriate concentration. The concentration of foliar fertilizer should be suitable for crops, more will not only cause waste, but also lead to drug damage. Generally speaking, the solution concentration of a large number of nutrient elements is about 0.2% Mel 2%, and the solution of trace elements is approximately 0.01% Mel 0.1%. Fourth, we should pay attention to the back of the spray leaf. The vegetable leaf back has many pores, the tissue is looser, the nutrients are more easily infiltrated, and the leaf back solution dries slowly, so the effect will be better after spraying. Therefore, when applying fertilizer outside the root, we should not only spray the positive fertilizer of the leaf, but also pay attention to spraying the reverse side of the leaf. If boron, calcium, iron, manganese, molybdenum and zinc are sprayed, they are generally required to be sprayed on new shoots and leaves. In addition, vegetable farmers need to be reminded that although extra-root topdressing has a good effect and quick effect, it can not replace soil fertilization. Because the amount of nutrients absorbed by vegetables outside the root is very small, it is impossible to completely use extra-root fertilization instead of soil rhizosphere fertilization, especially a large number of nutrient elements, should be based on soil fertilization, extra-root fertilization is only an auxiliary method. Click to get more compound fertilizer application techniques