What should we pay attention to when applying urea to farmland?

What should we pay attention to when applying urea to farmland? Please introduce that urea is a favorite nitrogen fertilizer for farmers because of its convenient use and high fertilizer efficiency. It can be used not only as base fertilizer and topdressing, but also as extra-root topdressing. If it is not applied properly, it will not only cause a waste of fertilizer, but also cause "fertilizer damage" and harm crops. Therefore, we must pay attention to "eight taboos" when applying urea. One is forbidden to apply mixed with alkaline fertilizer or at the same time. Alkaline fertilizers include plant ash, lime, calcium magnesium phosphate fertilizer, steel slag phosphate fertilizer and so on. If mixed urea is applied or applied at the same time, it will aggravate the volatilization of nitrogen in urea into ammonia. Therefore, urea and alkaline fertilizer should be staggered for 3 to 4 days in summer and autumn, and 7 to 8 days in winter and spring. Second, avoid being used as a kind of fertilizer. Urea as seed fertilizer, due to the toxic effect of concentrated biuret, the seeds will lose their germination power and endanger the seedlings. At the same time, because high concentration of urea can destroy the protein structure of seeds, and also has toxic and inhibitory effect on seeds, it is not suitable to be used as seed fertilizer. If it must be used as seed fertilizer, the contact between seed and fertilizer should be avoided and the dosage should be controlled. Three taboos water immediately after application. The adsorption capacity between amide nitrogen and soil colloid is very low, and its fluidity and leaching in soil is not less than that of nitrate nitrogen fertilizer. In view of these properties of urea, after topdressing urea, do not water it before its conversion is completed, otherwise it will be wasted. In general, it should be watered 2 to 3 days after application in summer and autumn, and 7 to 8 days after application in winter and spring. The topdressing of urea for rice should also control the dazzling in the shallow water layer, ploughing in the middle after application, so that the soil and fertilizer can be mixed, and urea can not be applied before heavy rain. Four taboos are shallowly applied. Shallow application of urea nutrients are easy to volatilize and easy to be consumed by weeds. The deep application of urea will melt fertilizer into the soil and make the fertilizer in the wet soil layer, which is beneficial to the exertion of fertilizer effect. Topdressing should be applied on the side of the seedling or ditch on the side of the seedling, and the depth should be about 10 to 15 cm. In this way, urea can mostly be concentrated in the root dense layer through movement, which is convenient for crops to absorb and use. Fifth, do not use too much. The nitrogen content of urea is 44% to 48%, the nutrient content is high, and the application amount should not be too large, so as to avoid unnecessary waste and "fertilizer damage". Generally, the application rate is 5 to 15 kg per mu in dry land and 15 to 20 kg per mu in paddy field. Six taboo high concentration foliar spraying. Foliar spraying must avoid excessive concentration of urea solution, otherwise it will burn out the leaves and poison the plants. Usually the concentration of corn, wheat, rice and cotton is 2%; the concentration of vegetables, melons and fruits is 0.5% to 1%; and the concentration of fruit trees is 0.5% to 1.5%. Avoid using it too late. If urea is applied too late, it is not conducive to the exertion of fertilizer effect, and it is easy to cause crops to be green and mature late, so it should be applied 4 to 7 days earlier than other nitrogen fertilizers. Eight taboos for single application. Urea should be applied in conjunction with organic fertilizer and phosphorus and potassium fertilizer to meet the needs of various nutrients for crops. For example, the mixed application of urea and calcium superphosphate can transform unstable ammonium hydrogen sulfate into stable ammonium phosphate, accelerate the transformation and decomposition of urea, make available nitrogen quickly absorbed by crops and improve the utilization rate of urea. Click to get more nitrogen, phosphorus, potassium application techniques click to get more fertilizer application techniques