There are 8 wrong uses of urea, how many have you misused?

Urea is very popular among farmers because of its high nitrogen content, long fertility and easy to use. However, in order to give full play to the role of urea, it is necessary to master the correct method of use, and pay attention to the following eight points:

1. Avoid mixed application with alkaline fertilizer or at the same time.

Urea must be converted into ammonia nitrogen to produce fertilizer effect, and most of ammonia nitrogen will be volatilized into ammonia under alkaline conditions, 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.

2. Avoid using mixed seed fertilizer.

Urea often produces a small amount of secondary vein contraction in the production process, and when the second vein content is more than 2%, it will be toxic to seeds and seedlings. 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, avoid contact between seed and fertilizer and control the amount of fertilizer used.

3. 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 2-10 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. It should be irrigated 7-8 days after application in winter and spring, and 2-3 days after application in summer and autumn.

4. Do not spread urea on the surface.

When spread on the surface, it can only be used after 4-5 days of transformation at room temperature. most of the nitrogen is easy to volatilize in the ammoniation process, and the actual utilization rate is only about 30%. The loss of nitrogen in alkaline soil and soil with high content of organic matter will be faster and more. Moreover, the shallow application of urea is easy to be consumed by weeds, and the deep application of urea in the soil makes the fertilizer in the wet soil layer, which is beneficial to the exertion of fertilizer efficiency. Topdressing should be applied on the side of the seedling or furrow on the side of the seedling, and the depth should be about 10-15 cm. In this way, urea is concentrated in the dense layer of roots to facilitate the absorption and utilization of crops. The experimental results show that deep application can increase the utilization rate of urea by 10% and 30% compared with shallow application.

5. Excessive dosage should be avoided.

Urea has high nitrogen content and should not be applied too much, so as to avoid unnecessary waste and "fertilizer damage". Generally, 15-20 kg per mu is applied. 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 into groundwater, which will lead to nitrogen pollution and nitrite deposition in the water body, which will seriously affect the safety of human and livestock.

6. Avoid high concentration foliar spraying.

Urea is the most ideal foliar fertilizer among all nitrogen fertilizers. The amount and speed of protein synthesis by spraying urea 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. The suitable concentration for spraying wheat and corn is 2%, and that for vegetables and melons is 0. 5%. 5%-1. 5% is appropriate.

7. Avoid using it too late.

The application of urea too late is not conducive to the effect of fertilizer, 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.

8. Avoid applying it to celery.

Celery needs to apply a large amount of nitrogen fertilizer during the whole growth period, but not urea. Because topdressing urea will make celery fiber increase and thicken, plant aging and growth slow. And the taste is bitter and the quality is poor. Celery is suitable to apply ammonium bicarbonate, ammonia and mature organic fertilizer to improve the quality.