The Correct Way to Use Urea

Balanced Fertilization
Urea is a pure nitrogen fertilizer, does not contain phosphorus and potassium, which are essential elements for crop growth. Therefore, when doing fertilizer tracking, you should use formula fertilization techniques based on soil testing, and apply nitrogen, phosphorus and potassium fertilizers in a balanced manner. First, all the phosphorus and potassium fertilizers and part (about 30%) of the nitrogen fertilizers required for the whole crop fertility period should be combined with the bottom application of the whole land. Then the remaining 70% of the nitrogen fertilizer (you can use urea) as a follow-up fertilizer, of which the crop's fertilizer needs of the critical period, the maximum efficiency of about 60% of the follow-up, the late follow-up of about 10%. Only nitrogen, phosphorus, potassium three kinds of fertilizer reasonable cooperation, scientific application into, in order to make the chase urea utilization rate increased.

The Right Period of Chasing
Each crop has a specific critical period for the absorption of nitrogen, phosphorus and potassium (i.e., the period when the crop is particularly sensitive to the absorption of certain elements). The lack of fertilizer (nitrogen, phosphorus, potassium) during this period will reduce the yield and quality of the crop, which will have a huge impact. In addition, there is a maximum efficiency period, that is, the crop can obtain a higher yield during this period of fertilization, the crop to the highest efficiency of fertilizer use. From the above analysis, it can be seen that only in the nutrient critical period and maximum efficiency period of the crop fertilizer can improve the utilization rate of fertilizer, so that the crop can achieve high yield and quality.
Different crops have different fertilizer requirement critical period and maximum efficiency period, which should be treated differently and applied reasonably. For example, the critical period of nitrogen requirement for wheat, corn and other grass crops is at the tiller stage and spike differentiation stage, and cotton is at the boll stage. The maximum efficiency period of nitrogen is from nodulation to gestation for wheat, from tillering to nodulation for rice, from trumpeting for corn, from fruiting for tomato, from rosette for cabbage, from bud for sunflower, from first flowering for soybean, etc.

Timely Fertilization
Urea is an amide fertilizer, which needs to be converted into ammonium carbonate to be adsorbed by soil colloids and then absorbed by crops, a process that takes 6-7 days, during which urea is first dissolved by the water in the soil and then slowly converted into ammonium carbonate. Therefore, when urea is applied as a fertilizer, it should be applied about 1 week before the critical period of nitrogen demand and maximum efficiency of the fertilizer, not too early or too late.

Deep Application of Mulch
Improper application method is very likely to cause urea loss with water, ammonia volatilization and other nitrogen loss phenomenon, waste fertilizer, labor, but also greatly reduce the utilization rate of urea.
The correct method of application is: in corn, wheat, tomatoes, cabbage and other crops, should be 20 cm from the crop, digging 15-20 cm deep hole, the fertilizer will be applied to the soil with soil cover tightly, in the case of soil is not too dry 7 days after watering. When the soil is seriously dry and really needs watering, it should be lightly watered once with small amount of water, not a large amount of water to prevent the loss of urea with water. When applied on rice, should be used to spread, after application to keep the soil moist, 7 days can not irrigate, wait for the fertilizer fully dissolved by the soil adsorption, can be watered once a small water, and then dry 5 to 6 days.

Foliar Spraying
Urea is easily soluble in water, strong diffusion, easy to be absorbed by the leaves, less damage to the leaves, suitable for extra-root fertilizer, can be combined with crop pest control for foliar spraying. However, when doing extra-root fertilizer, should choose urea with no more than 2% diurea content to prevent damage to the leaves. The concentration of extra-root fertilizer varies according to the crop. Spraying time is appropriate after 4 pm, when transpiration is small, leaf stomata gradually open, conducive to the full absorption of urea aqueous solution of crops.