1, urea, also known as formamide, is a white crystal. It is a neutral quick-acting fertilizer, which is suitable for all kinds of soil and plants. Urea will not leave harmful substances in the soil and can be used for a long time. It is easy to store and use. Carbon dioxide and ammonia can be used in industry, and urea can be directly synthesized under certain conditions. Urea is widely used. The function and efficacy of urea can be used not only as synthetic fertilizer, but also as raw material for producing drugs, food, moisture absorbent and resin treatment. Conversion of urea into soil
2. After urea is applied to the soil, a small part is absorbed by the soil, and the rest is hydrolyzed into ammonium carbonate to form ammonium bicarbonate and ammonium hydroxide. Generally speaking, urea is applied 4-8 days before the crops need fertilization. Urea is suitable for neutral soil. The function and efficacy of chemical fertilizer urea are appropriate. The higher the soil temperature, the faster the transformation speed. If the temperature reaches 10℃, it will take about 7- 10 days to completely transform into ammonium nitrogen. 4-5 days at 20℃ and 2-3 days at 30℃. In order to slow down the hydrolysis and nitrification of urea and prolong the release period of nitrogen in urea, urease inhibitor or nitrification inhibitor will be added to new urea.
3. Improving soil organic matter can effectively promote the absorption rate of nitrogen by urea, because urease exists in plants and is secreted by many microorganisms, and its quantitative activity is also related to soil organic matter content. Precautions for use, urea is suitable for most crops and soils. Can be used as base fertilizer and topdressing. It can also be used in dry fields. In alkaline soil, urea should be deeply applied with mulch fertilizer to improve the function and efficacy of urea. It is not suitable for surface application, which easily leads to volatilization loss of ammonium. When nitrogen fertilizer is applied to the surface of rice field, the ammonia volatilization loss is about 10-30%. For example, in alkaline soil, the volatilization of ammonia is about 12-60%.
4, urea dosage should not be too much or too dense. When its concentration is 0.05%, it can inhibit the young roots and buds of crops. Generally, urea can not be directly absorbed and utilized by crops after application, and needs to be converted into ammonium nitrogen. Under the action of alkalinity, a large amount of nitrogen in ammonium nitrogen will volatilize. Therefore, urea should not be mixed with alkaline fertilizers such as calcium magnesium phosphate, plant ash and ammonium bicarbonate.