What should be paid attention to when applying nitrogen fertilizer to crops?

First, ammonium nitrogen fertilizer should not be mixed with alkaline fertilizer. After mixing, ammonia volatilization will occur and the fertilizer effect will be reduced. Second, the nitrate nitrogen fertilizer should not be mixed with organic fertilizer. The organic matter in the organic fertilizer will undergo nitrification and lose nitrogen when it is nitrated. Third, nitrate fertilizer should not be administered in paddy fields, nitrate fertilizer nitrogen loss caused easily decomposed gas under anaerobic conditions. Fourth, urea is not suitable for pouring. Urea will be hydrolyzed to ammonium bicarbonate by the action of soil microorganisms to decompose ammonia and then volatilize. Fifth, urea should not be close to the seed. Urea will affect the germination of the seed . When the concentration is too high, the seed will be poisoned. Sixth, the concentration of urea as a root dressing should not be too high. Seventh, ammonium bicarbonate should not be applied to the surface of the soil. The nature of ammonium bicarbonate is unstable and should be covered immediately after application. Eight is that ammonium sulfate is not suitable for long-term application, otherwise it will increase soil acidity and destroy soil structure. Nine is ammonium sulfate and should not be applied in paddy fields. Ten is that ammonium chloride should not be applied to the chlorine-killing crops, otherwise the physiological functions of the crops will be destroyed or even killed.