How to apply urea?

How to apply urea? Please introduce that it is suitable for extra-root topdressing. Urea is a neutral fertilizer, which has less damage to crop leaves, is easy to dissolve in water, has strong diffusivity, is easy to be absorbed by leaves, and is not easy to cause plasmolysis after entering the leaves, so it is very suitable for extra-root topdressing. However, urea with biuret content not more than 2% should be selected to prevent damage to the leaves. Generally, the amount of fertilizer applied outside the root of urea per mu is 0.5-1.5 kg. The suitable spraying time is after 4: 00 p. M., when the transpiration is less, the leaf stomata open gradually, the diluted urea solution can be absorbed overnight, and the utilization rate of urea is greatly improved. Second, it is necessary to apply it early and deeply. First, give it early. The application of urea into soil requires a transformation process before it can be absorbed and utilized by crops. Therefore, if the application time of urea is the same as that of other nitrogen fertilizers, it will delay the maximum effect period of nitrogen uptake by crops. Second, we should apply it deeply. Whether urea is used as base fertilizer or topdressing fertilizer, it should be deeply covered with soil. Deep application can control the hydrolysis rate of urea, make it release nitrogen nutrition evenly, prevent the volatilization loss of nitrogen and improve the utilization rate. Third, it is not suitable for surface application, seed soaking and irrigation immediately after application. First, it is not suitable to act on the surface. In particular, saline-alkali land is more unsuitable for spreading on the surface. This is because ammonium carbonate, ammonium bicarbonate and ammonium hydroxide produced after urea decomposition are all unstable compounds. Second, it is not suitable for soaking and mixing seeds. Urea contains a small amount of biuret, which is toxic to crops. Soaking and mixing seeds with urea will destroy the protein structure of seeds, cause protein denaturation, and affect seed germination and root growth of seedlings. Third, it is not suitable to irrigate immediately after application. After urea is applied into the soil, it dissolves in the soil solution in molecular state before it is converted into ammonium bicarbonate, and it is not easy to be absorbed by the soil. If you irrigate immediately, the fertilizer will be lost with the water, and the fertilizer will be irrigated every few days after application. Click to get more nitrogen, phosphorus, potassium application techniques click to get more fertilizer application techniques