How to Improve Urea Topdressing Effect?
(1) Determine the application amount of fertilizer according to fertility. In the case of corn, 20kg per acre of high-fertility soil, 23kg per acre of medium-fertility soil and 27kg of low-yielding soil should be applied.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.
(2) As far as possible, top dressing should be done in the peak nutrition stage of crops: corn should be jointed to the big trumpet mouth stage, sorghum should be jointed to the booting stage, wheat should be in the three-leaf stage, and soybean should be in the early flowering stage.
(3) Apply soil deeply. When applying fertilizer to upland crops with urea, it is best to dig pits or open trenches to apply more than 10 cm deepth, so as to make urea in moist soil, which is conducive to the conversion of urea, but also conducive to the adsorption of ammonia fertilizer by the soil, reducing the loss of volatilization. and other organic fertilizer and npk compouond fertilizer is necessary for the crops and soil.
(4) Keep a certain distance from crops. When applying fertilizer, it is necessary to prevent urea from being applied near the root system of the crop, not to drop urea into the heart leaves of the crop, so as not to burn the seedlings and affect the growth, and to maintain a certain distance from the crop.
(5) Application in advance of other nitrogen fertilizers. When applying urea to crop topdressing fertilizer, it should be applied about 7 days ahead of other nitrogen fertilizers.
(6) Do not mix with alkaline fertilizer. Urea belongs to neutral fertilizer, do not mix with alkaline fertilizer when topdressing, in order to reduce the effect of fertilizer.
(7) Irrigation should not be carried out immediately after postharvest. After urea is applied into the soil, it cannot be absorbed by the soil before it is decomposed and transformed. If water is poured immediately after topdressing, urea can be lost.
(8) Apply fertilizer outside the root. Urea has less damage to crop leaves, is soluble in water, has strong diffusivity, and is easy to be absorbed by leaves. After entering leaves, it is not easy to cause plastic-wall separation. Therefore, urea is very suitable for root-topdressing. The concentration of topdressing outside the root of gramineous crops was 1.5-2%; the concentration of external top dressing for dicotyledonous crops was 1%. Generally, the amount of fertilizer applied outside the root of urea per mu is 0.5kg to 1.5kg. Spraying time should be done after 4 PM.