Application of urea in agriculture

Application of urea in agriculture

Urea is suitable as base fertilizer and topdressing, and sometimes as seed fertilizer. Urea is molecular before transformation and cannot be adsorbed by soil, so it should be prevented from losing with water; Ammonia formed after conversion is also volatile, so urea should also be deeply covered with soil. (a small part of the soil transformed and applied into the soil is dissolved in the soil solution in molecular state and adsorbed by the soil through hydrogen bonding. Most of the other parts are hydrolyzed into ammonium carbonate under the action of urease to produce carbonic acid and ammonium hydroxide. Then, ammonium ions can be absorbed by plants and soil colloids, and bicarbonate ions can also be absorbed by plants. Therefore, there is no residue after urea is applied into the soil In addition, biuret contained in urea can also be decomposed into ammonia and carbonic acid under the action of urease. The transformation of urea in the soil is affected by soil pH value, temperature and moisture. It is neutral in the soil. When the moisture is appropriate, the higher the soil temperature, the faster the transformation; when the soil temperature is 10 ℃, it takes 7-10 days for urea to completely convert into ammonium nitrogen, 4-5 days at 20 ℃ and 2-3 days at 30 ℃ Days. Ammonium nitrogen is generated after urea hydrolysis, and surface application will cause ammonia volatilization, especially in alkaline or alkaline soil. Therefore, when applying urea, the covering soil should be deeply applied, and the paddy field should be deeply applied to the reduction layer.)

Urea is suitable for all crops and all soils. It can be used as base fertilizer and topdressing. It can be applied in dry and paddy fields. The transformation of urea in soil can accumulate a large amount of ammonium ions, which will increase the pH by 2-3 units. In addition, urea itself contains a certain amount of biuret, which will inhibit crop young roots and buds when its concentration is 500ppm. Therefore, urea should not be used as seed fertilizer.