Urea is a kind of high concentration nitrogen fertilizer, belongs to the neutral quick effect fertilizer, it is also used for the production of npk compound fertilizer
. There are no harmful substances left in the soil, long-term application has no adverse effects. Urea is an organic nitrogen fertilizer, which 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 period of crops.
Urea is suitable for all kinds of soil and crops, which can be used as base fertilizer and topdressing fertilizer, generally not as seed fertilizer. When it is used as the base fertilizer in dry land, 20 kilograms is spread and turned over immediately on the farmland surface per acre. When it need to be applied in the paddy field as base fertilizer, application dosage is 15-20 kilograms per acre and it should spread 5-7 days in advance before irrigating water, plough over soil.
When it is used for topdressing in dry land, 10 kilograms of furrow or hole per acre should be applied in a depth of 7-10 cm. Paddy fields need drainage before applying urea as the topdressing, and then 8 kg urea per acre is applied to the topsoil before immediate irrigation.
Urea is used for topdressing 3-5 days in advance of other nitrogen fertilizers.
Urea is also suitable for topdressing outside the root, and the spraying concentration varies from different kinds of crops. General field crops commonly used about 1.0% concentration, poor growth or seedling stage can be appropriately reduced; The concentration of vegetables in open field is lower than that in field crops. Mulberry, tea, fruit trees and greenhouse vegetables should be lower. Each acre spray liquid 50 -- 75 kilograms, spray one time every 7 -- 10 days, 2 -- 3 times in all.