Does it work to sprinkle urea on sunny days after rain?

It helps to sprinkle urea on sunny days after rain. However, it is recommended to wait three or four days before sprinkling, because urea is a kind of fertilizer with strong water solubility. it can absorb water and dissolve even in the air, and it is not easy to be absorbed by the soil. If it rains, it will lead to fertilizer loss with water loss, which will lead to fertility loss and fertilizer damage in low-lying areas.

Ten taboos on the use of urea

1. Taboo mixed with ammonium bicarbonate

After urea is applied into soil, it must be converted into ammonia before it can be absorbed by crops, and its conversion rate under alkaline condition is much slower than that under acidic condition. Ammonium bicarbonate showed alkaline reaction after being applied to the soil, and the pH value was 8.2-8.4. The mixed application of ammonium bicarbonate and urea in farmland will greatly slow down the conversion of urea to 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.

2. Avoid spreading on the surface

Urea is spread on the surface and can only be used after 4-5 days of transformation at room temperature. most of the nitrogen is easily volatilized in the ammoniation process, and the actual utilization rate is only about 30%. If it is applied in alkaline soil and soil with high organic matter content, nitrogen loss will be faster and more.

And the shallow application of urea is easy to be consumed by weeds. The deep application of urea will melt fertilizer into the soil and make the fertilizer in the wet soil layer, which is beneficial to the exertion of fertilizer effect. Topdressing should be applied on the side of seedling or ditch on the side of seedling, and the depth should be about 10~15cm. In this way, urea is concentrated in the dense layer of root system, which is convenient for crop absorption and utilization. The experimental results show that deep application can increase the utilization rate of urea by 10% to 30% compared with shallow application.

3. Avoid being a seed fertilizer

In the process of urea production, a small amount of biuret is often produced, which will be toxic to seeds and seedlings when the biuret content is more than 2%. When such urea enters seeds and seedlings, it will cause protein denaturation and affect seed germination and seedling growth. therefore, it is not suitable to be used as seed fertilizer. If it must be used as seed fertilizer, the contact between seed and fertilizer should be avoided and the dosage should be controlled.

4. Irrigation immediately after application is prohibited.

Urea belongs to amide nitrogen fertilizer, which must be converted into ammonia nitrogen before it can be absorbed and utilized by crop roots. the transformation process takes a long and short time due to different soil quality, water and temperature, and generally can be completed after 2 to 10 days. if irrigation and drainage is applied immediately after application or dryland is applied before heavy rain, urea will be dissolved in water and lost. In general, irrigation should be done 2-3 days after application in summer and autumn, and 7-8 days after application in winter and spring.

5. Avoid mixed application or simultaneous application of alkaline fertilizer

Urea must be converted into ammonia nitrogen to produce fertilizer effect, and under alkaline conditions, most of the nitrogen will be volatilized into ammonia, so urea can not be mixed with alkaline fertilizers such as lime, plant ash, calcium magnesium phosphate fertilizer or at the same time. Generally speaking, urea and alkaline fertilizer should be staggered for 3-4 days in summer and autumn, and 7-8 days in winter and spring.

6. Do not apply it to celery

Celery needs to apply a large amount of nitrogen fertilizer during the whole growth period, but not urea. Because of topdressing urea, celery fiber increased and thickened, plant aging, slow growth, bitter taste and poor quality. Celery is suitable for ammonium bicarbonate, ammonia and organic fertilizer, which is beneficial to improve the quality.

7. Avoid using too much

Urea has high nitrogen content and should not be applied too much, so as to avoid unnecessary waste and "fertilizer damage". Generally, 515kg / mu and 15kg / mu are applied in paddy field. If it is applied too much, it can not be absorbed by the soil before it is converted to ammonium bicarbonate, so it is easy to be leached by Rain Water and easy to hurt crops. At the same time, if urea is applied too much, most of it will be lost and enter the groundwater, which will lead to nitrogen pollution and nitrite deposition in the water body, which will seriously affect the safety of human beings and animals.

8. Avoid high concentration foliar spraying

Among all the nitrogen fertilizers, urea is the most ideal foliar fertilizer. By spraying urea, the amount and speed of protein synthesis of crops are higher than that of other nitrogen fertilizers. However, when foliar spraying, the concentration of urea solution must not be too high, otherwise it will burn out the leaves and poison the plants. Usually the concentration of corn, wheat, rice and cotton is 2%; the concentration of vegetables, melons and fruits is 0.5-1%; and the concentration of fruit trees is 0.5-1.5%.

9. Avoid using it too late

The application of urea too late is not conducive to the exertion of fertilizer efficiency, and it is easy to cause crops to be green and mature late, so it should be applied 4-7 days earlier than other nitrogen fertilizers.

10. Avoid single application

The effective component of urea is nitrogen, the nutrient is single, and the growth and development of crops need a variety of nutrients. Therefore, urea should be applied in conjunction with organic fertilizer, phosphorus and potassium fertilizer to meet the needs of crops for various nutrients. Moreover, the reasonable mixed application of urea, organic fertilizer and chemical fertilizer can effectively improve its utilization rate. For example, the mixed application of urea and calcium superphosphate can transform unstable ammonium bicarbonate into stable ammonium phosphate, so that the natural volatilization of nitrogen is greatly reduced. The mixed application of urea and organic fertilizer can not only produce organic acids in the process of fermentation, but also accelerate the transformation and decomposition of urea, which can be quickly absorbed by crops and improve the utilization rate of urea.

The above is the introduction of the effect of sprinkling urea on sunny days after rain. I hope it will be helpful to you.