Fertilize with urea? What are the things to pay attention to

Urea is one of the fertilizers widely used in agricultural production, which can provide nitrogen for crop growth. However, the use of urea also has some requirements and contraindications, otherwise it will cause the loss of urea, reduce the utilization rate of fertilizer, and affect the safe growth and ripening of crops. So how to use urea properly? What are the taboos?

Try not to use it as seed fertilizer. Urea is easily soluble in water and can easily absorb water from the air for dissolution and agglomeration during conventional storage. When applied to the soil, it quickly absorbs water from the soil and dissolves it. If used as a seed fertilizer, it is easy to have some adverse effects on ungerminated seeds, such as seed burning and uneven emergence.

Urea needs to be used in sections. Urea is a medium – speed fertilizer. Compared with ammonium nitrogen and nitrate nitrogen, it has a certain advantage in the duration of fertilizer effect. However, compared with diamine and other compound fertilizers, urea also has a short duration of fertilizer effect. Therefore, urea needs to be reused in stages in agriculture to meet the nitrogen requirements of crops throughout the growing period.

However, this does not mean that urea can be overused at will. Once overused, the crop will develop overgrowth, late ripening, lodging and other adverse conditions. Therefore, in addition to the segmented use of urea, it is also necessary to use appropriate amounts to achieve better results.

The concentration of foliar spraying needs to be well controlled. Urea is also a small molecule that can be absorbed into the plant through the leaves and used. In addition, urea spraying is also used by many farmers to alleviate mild nitrogen deficiency symptoms, and the cost is very low.

However, we must control the concentration of the diluted urea solution, which is usually controlled between 0.1 and 0.3%. This concentration range is relatively safe. In addition, urea needs to be used according to the growth of the crop. Remember not to blindly spray multiple times to avoid some negative situations; At the same time, it should not be done in the middle of the day during high temperatures to prevent fertilizer damage.

Use in advance. Urea is not immediately absorbed by the crop after application. Urease in the soil needs to convert it into ammonium bicarbonate before it can be taken up by the roots. Generally, this process takes about 3-4 days. In addition to the transformation of plants to use the process, use after 5-7 days or so will produce obvious fertilizer reaction. Therefore, during the growing season when top-up nitrogen fertilizer is needed, pit or ditch application can be made about 2-4 days in advance.

Urea is also contraindicated. Avoid mixing ammonium bicarbonate with urea. When applied to the soil, it must be converted to ammonia nitrogen before it can be taken up by the crop. Under alkaline conditions, the conversion rate is much slower than that under acidic conditions. Alkaline ammonium bicarbonate applied to soil can greatly slow down the conversion rate of urea to ammonia, which is easy to cause loss and volatilization of urea. Therefore, urea and ammonium bicarbonate should not be mixed or used together.

Avoid surface coating. Urea can only be used after 4 to 5 days of surface transformation at room temperature. Most urea is volatile in the ammoniation process, and the actual utilization rate is only about 30%. If applied to alkaline soils and soils with high organic matter content, nitrogen loss will be more and more rapid. In addition, shallow application of urea is easy to be consumed by weeds. Deep application of urea can increase urea utilization by 10%-30% compared with shallow application.

Do not water immediately after applying. Urea is an amide nitrogen fertilizer. It needs to be converted to ammonia nitrogen before it can be taken up and used by crop roots. Generally speaking, it takes 20 days to complete the transformation after application to the soil. If watered immediately after use, urea will dissolve in the water and run off.

Avoid mixing alkaline fertilizers. After the application of urea, it needs to be converted into ammonia nitrogen to produce fertilizer efficiency. Under alkaline conditions, most of the nitrogen will turn into ammonia and evaporate. Therefore, urea should not be mixed or used with lime, plant ash, calcium and magnesium phosphate and other alkaline fertilizers. It should be staggered five to seven days.

Urea alone is prohibited. Urea nutrient is single, crop growth and development need a variety of nutrients. Therefore, urea should be used in combination with organic fertilizer, phosphate fertilizer and potassium fertilizer, which is easily satisfied. It can be used as the nutrient requirement of aluminum-free shell crops. Urea Shuyu organic fertilizer and chemical fertilizer should be properly combined.

It can also effectively improve its utilization. For example, a mixture of urea and superphosphate can convert unstable ammonium bicarbonate into stable ammonium phosphate. In this way, the natural volatilization of nitrogen will greatly reduce the mixed use of urea and organic fertilizers. The organic acids produced in the fermentation process can also accelerate the conversion and decomposition of urea, which can be quickly absorbed by crops and improve the utilization rate of urea.

You can’t make seed fertilizer during use. There’s a lot of things to be aware of in the use of urea, there’s a lot of knowledge. In addition, some crops are sensitive to urea, so we should pay special attention to it.