As a neutral fertilizer, urea is suitable for all kinds of soil and plants. It is easy to preserve, easy to use and has little damage to soil. It is a chemical nitrogen fertilizer with large use and the highest nitrogen content. Urea is a kind of high concentration nitrogen fertilizer, which is a neutral quick acting fertilizer. It can also be used to produce a variety of compound fertilizers. No harmful substances remain in the soil, and long-term application has no adverse effects. Animal husbandry can be used as feed for ruminants. However, too high temperature in granulation will produce a small amount of biuret, also known as biuret, which can inhibit crops. China stipulates that the content of urea biuret for fertilizer should be less than 0.5%. When the biuret content exceeds 1%, it cannot be used as seed fertilizer, seedling fertilizer and leaf fertilizer, and the urea content in other application periods should not be too much or too concentrated. Urea is an organic nitrogen fertilizer. It can be absorbed and utilized by crops only after it is hydrolyzed into ammonium carbonate or ammonium bicarbonate by urease in soil. Therefore, urea should be applied 4 ~ 8 days before the fertilizer demand period of crops. 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. 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 500 ppm. Therefore, urea should not be used as seed fertilizer. Urea (nitrogen fertilizer) can promote cell division and growth and make branches and leaves flourish.
Effect of urea:
Adjust flower amount: In order to overcome the problem of large and small years of Apple field, spraying 0.5% urea aqueous solution on the leaf surface 5-6 weeks after flowering (the critical period of apple flower bud differentiation, the growth of new shoots is slow or stops, and the nitrogen content of leaves shows a downward trend) for two times can improve the nitrogen content of leaves, accelerate the growth of new shoots, inhibit flower bud differentiation, and make the flower volume suitable for large years.
Thinning flowers and fruits: The flower and fruit thinning of peach and nectarine requires a large concentration (7.4%) to show good results. The most suitable concentration is 8% – 12%. The purpose of flower and fruit thinning can be achieved within 1-2 weeks after spraying urea aqueous solution.
Pest control: After mixing 4:1:400 portions of urea, washing powder and clean water, it can prevent aphids, red spiders, cabbage worms and other pests on fruit trees, vegetables and cotton, and the insecticidal effect is more than 90%.
Post time: Nov-30-2021