Precautions for using nitrogen fertilizer

Implement mixed application, deep application, and strengthen water management. A large number of field experiments show that compared with surface application of nitrogen fertilizer, mixed application of nitrogen fertilizer in the soil layer, or applied to a few centimeters deep below the soil surface, can reduce nitrogen loss. Nitrogen fertilizer is made into granular fertilizer of a few millimeters or 1 centimeter in size for deep application, and the effect is better.

Rice field experiments show that deep application of grain fertilizer can achieve the same yield level as surface application of powder fertilizer, while the amount of nitrogen fertilizer can be reduced by about 1/3. However, in areas where rainfall is high, soil texture is light, and leaching loss may occur, deep application should be used with caution. Mixed application and deep application have the effect of reducing ammonia volatilization and denitrification loss. Proper water management can also achieve the purpose of increasing the yield of nitrogen fertilizer. For example, basal fertilizers applied to rice fields are mostly mixed when there is a water layer. The effect of this mixed application is very poor. Most of the nitrogen is still in the field water, and only a small part of the nitrogen is mixed into the soil. Adopting the method of mixing nitrogen fertilizer and then irrigating when there is no water layer can mix more nitrogen into the soil, thereby reducing nitrogen loss. In addition, after surface application of nitrogen fertilizer, irrigate water to allow the water to bring the fertilizer into the soil. This method of carrying nitrogen with water is also one of the measures to reduce the loss of nitrogen.

Choose slow-acting (long-acting) fertilizers Slow-acting fertilizers are granular nitrogen fertilizers covered with a film to gradually release soluble nitrogen for crops to absorb and use, reducing nitrogen loss. The application of slow-acting fertilizers can reduce nitrogen loss to a certain extent, but due to its high price, the application objects are mainly cash crops.

Choose the fertilization period According to the characteristics of the nitrogen demand of the crop, the fertilization period can be selected to make the crops high-yield. Otherwise, the straw of the cereal crops will have high nitrogen content and the grain yield will not be high. For crops with a long growth period, in addition to the application of base fertilizer, nitrogen fertilizer should be applied one to several times according to the characteristics of the nitrogen demand of the crop to meet the needs of the crop and obtain high yield.

Application due to soil texture The texture and organic matter content of the soil affect the application of nitrogen fertilizer. It is generally believed that sandy soil mineralizes quickly and has poor fertility retention, and should be applied less frequently; while clay soil organic matter mineralization is slow, and the nitrogen fertilizer applied is easily adsorbed by soil colloids and fixed by microorganisms, and has strong fertility retention performance. , Can be small and large; and loamy soil has excellent fertilization and fertilizer retention performance, and the fertilization method can be determined according to the growth period of the plant.

Depending on the type of crop, different plants have different requirements and types of nitrogen fertilizer. For example, leafy vegetables, tea trees, mulberry trees and other plants that harvest leaves require a large amount of nitrogen, and ammonium nitrogen is suitable; bark, fiber plants such as hemp, eucommia, phellodendron amurense, etc., use ammonium chloride; flowers and fruit trees Nitrate-nitrogen fertilizer is often more appropriate; the nitrogen requirements of the same plant are different in different periods. In a year, the nitrogen requirement in spring and summer is more than 52%, and the demand decreases during the fruit expansion period. Therefore, nitrogen fertilizer should be applied at the right time and early, especially during the ripening period of the fruit, to prevent greedy green and late ripening.

Using urease inhibitorsUsing urease inhibitors is to inhibit the hydrolysis of urea by urease, so that urea can diffuse and move to deeper soil layers, thereby reducing the total concentration of ammonium and ammonia nitrogen in the surface soil of dry land or in the water surface of paddy fields. To reduce the loss of ammonia volatilization. At present, the most researched urease inhibitors are O-phenylphosphoric diamide, N-butyl thiophosphoric triamide and hydroquinone.

Use of nitrification inhibitors The role of nitrification inhibitors is to inhibit the conversion of nitrifying bacteria from ammonium nitrogen to nitrate nitrogen, thereby reducing the leaching loss of nitrate due to nitrogen denitrification.