The theoretical nitrogen content of urea is 45-46%, but the actual situation may be slightly lower, because fertilizers generally contain a small amount of impurities. Urea is suitable for most crops and soils, and can be used as base fertilizer or topdressing. When it is used as base fertilizer, a ditch with a depth of about 10 cm can be dug in the planting area, and then the soil is covered with fertilizer, and the dosage of field crops is about 15-20 kg.

Generally, the validity period of urea is about 40-60 days. If it is long-acting urea, the validity period will be doubled to 1 10- 130 days or so. When corn, wheat, tomato, cabbage and other crops are topdressing, dig a pit with a depth of15-20cm at a distance of 20 cm from the root of the crop, and cover it tightly with soil after applying fertilizer.

The role of agricultural urea

1, seedling effect

After the crop germinates, the most needed nutrient element is nitrogen. Only nitrogen provides sufficient nutrition for the cells in the crop, provides a material basis for the division and growth of the crop cells, promotes the absorption of phosphorus and potassium, makes the cells elongate and expand rapidly, and the crop begins to grow. Therefore, topdressing urea at crop seedling stage can quickly promote the growth of seedlings and has the effect of raising seedlings.

2. Root ascension

The main material basis of crop root elongation growth comes from nitrogen nutrient fertilizer, so the growth of crop root system cannot be separated from nitrogen. Therefore, urea can promote the rapid rooting of crops.