Correct application of urea
Send Time:2023-2-12
Urea as a neutral fertilizer, urea is suitable for all kinds of soil and plants. However, if the application method is not correct and the application period is not suitable, it will lead to a significant decline in its utilization rate, and may even cause "fertilizer damage". Therefore, it is necessary to apply urea correctly and scientifically.
First, avoid mixing with ammonium bicarbonate
When urea is applied to the soil, it must be converted into ammonia before it can be absorbed by crops, and its conversion rate is much slower under alkaline conditions than under acidic conditions. The application of ammonium bicarbonate into the soil presents an alkaline reaction with ph value of 8.2 ~ 8.4. Mixed application of ammonium bicarbonate and urea in farmland will greatly slow down the conversion rate of urea into ammonia, which is easy to cause urea loss and volatilization loss. Therefore, urea and ammonium bicarbonate should not be mixed or applied at the same time.
Two, avoid the surface of the spread
Urea is spread on the surface, at room temperature after 4 to 5 days of transformation to be used, most nitrogen is easy to volatilize in the process of ammonia, the general actual utilization rate is only about 30%, if in alkaline soil and soil with high organic matter content, nitrogen loss will be faster and more. And urea shallow application, easy to be consumed by weeds. Topdressing should be applied at the side of the seedling or at the side of the ditch to facilitate the absorption and utilization of crops. It was proved that deep application could increase the urea utilization rate by 10% ~ 30% compared with shallow application.
Three, avoid planting fertilizer
Urea in the production process, often produce a small amount of biuret, biuret content when more than 2% will be toxic to seeds and seedlings, such urea into seeds and seedlings, will make protein denaturation, affect seed germination and seedling growth, so it is not suitable for seed fertilizer.
Four, bogey immediately after irrigation
Urea is an amide nitrogen fertilizer, it must be converted into ammonia nitrogen to be absorbed and used by crop roots, conversion process because of soil, water and temperature conditions are different, the time is long and short, generally after 2 ~ 10 days to complete, if immediately after irrigation and drainage or dry land applied before heavy rain, urea will dissolve in water and loss. General summer and autumn seasons should be 2 ~ 3 days after application before irrigation, winter and spring seasons should be 7 ~ 8 days after application.
Fifth, do not mix with alkaline fertilizer or apply at the same time
Urea application must be converted into ammonia nitrogen to produce fertilizer effect, and ammonia nitrogen under alkaline conditions, most nitrogen will become ammonia gas volatilized, so urea can not be mixed with lime, grass and wood ash, calcium magnesium phosphate fertilizer and other alkaline fertilizer or application at the same time. Generally speaking, urea and alkaline fertilizer should be staggered 3 ~ 4 days in summer and autumn, and 7 ~ 8 days in winter and spring.
Six, avoid putting on celery
A large amount of nitrogen fertilizer should be applied to celery during the whole growth period, but urea should not be applied. Because of urea application, celery fiber increased and coarse, plant aging, slow growth, and edible bitter, poor quality. The suitable application of ammonium bicarbonate, ammonia water and organic fertilizer is beneficial to improve the quality of celery.
Seven, avoid excessive consumption
Urea nitrogen content is high, the application amount should not be too large, so as not to cause unnecessary waste and "fertilizer damage". In general, 5 ~ 15 kg is applied per mu, and 15 ~ 20 kg is applied per mu in paddy field. Excessive application can not be absorbed by soil before conversion to ammonium bicarbonate, and is easy to be lost by rain, and easy to damage crops. At the same time, excessive urea application, most of the loss, into groundwater, will lead to water nitrogen pollution, resulting in nitrite deposition, serious impact on human and animal safety.
Eight, avoid high concentration foliar spray
Of all nitrogen fertilizers, urea is the most desirable foliar fertilizer. When urea was applied, the amount and rate of protein synthesis of crops exceeded that of other nitrogen fertilizers. However, the concentration of urea solution should not be too high when spraying the leaf surface, otherwise it will burn the leaves and poison the plant. Usually for corn, wheat, rice, cotton concentration of 2% is appropriate; Vegetables, melons and fruits to 0.5-1% is more appropriate; Fruit trees are suitable for 0.5-1.5%.
Nine, avoid applying too late
Applying urea too late is not conducive to the play of fertilizer effect and easy to cause crop greedy green and late ripening, so it should be applied 4 ~ 7 days earlier than other nitrogen fertilizers.
Ten, avoid single application
The effective component of urea is nitrogen, and the nutrient is simple, but the growth and development of crops need a variety of nutrients. Therefore, urea should be combined with organic fertilizer and phosphorus, potassium fertilizer, etc., in order to meet the needs of crops for various nutrients.
And urea with organic fertilizer and chemical fertilizer mixed reasonably, but also effectively improve its utilization rate. For example, urea mixed with superphosphate can transform unstable ammonium bicarbonate into stable ammonium phosphate, so that the natural volatilization of nitrogen is greatly reduced. Urea and organic fertilizer mixed application, in the fermentation process to produce organic acid, can also accelerate the conversion and decomposition of urea, quickly absorbed by crops, improve the utilization rate of urea.
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