Technical points of High efficiency fertilization for Common Chemical Fertilizer

Urea

Urea is a kind of high concentration acylamine nitrogen fertilizer. At present, it is the fertilizer with the highest nitrogen content in solid nitrogen fertilizer in China, and it is a neutral quick-acting fertilizer. After being applied into soil, it can be converted into ammonium carbonate or ammonium bicarbonate before it can be absorbed and utilized by crops. Therefore, the base fertilizer should be applied deeply, and it should be applied 4 or 5 days earlier than ammonium bicarbonate and ammonium sulfate. Urea is molecular before conversion and cannot be absorbed by soil. It should be prevented from losing with water. The ammonia formed after conversion is also easy to volatilize, so urea should also be applied deeply to cover the soil, and it is not suitable to irrigate immediately after application. If irrigation immediately after topdressing, it is easy to make urea lose with water, it should be reirrigated after an interval of 4-6 days. Urea should not be used as seed fertilizer directly, because the high concentration of urea is in direct contact with seeds, which often affects seed germination and results in uneven emergence. When urea is used as foliar fertilizer, the concentration of urea should be strictly controlled. Generally, the concentration of Gramineae crops is 1.5%-2%, fruit trees is about 0.5%, open-field vegetables is 0.5%-1.5%, greenhouse vegetables is 0.2%-0.3%. For crops in the peak growth period, or adult fruit trees, the concentration of urea can be appropriately increased.

Ammonium bicarbonate

Referred to as ammonium bicarbonate, the nitrogen content is about 17%. It is the lowest nitrogen content in solid nitrogen fertilizer. Ammonium bicarbonate has a general water content of 5% to 6%, which is easy to dissolve and agglomerate. The temperature is relatively stable below 20 ℃. If the temperature is slightly higher or the moisture in the product exceeds a certain standard, ammonium bicarbonate will be decomposed into ammonia and carbon dioxide, and the gas will escape in the air, resulting in the loss of nitrogen fertilizer efficiency. It is physiologically neutral available nitrogen fertilizer, which is suitable for all kinds of crops and soils, and can be used as both base fertilizer and topdressing fertilizer. When ammonium bicarbonate is used as base fertilizer, it can be applied in ditch or hole. If it can be combined with the deep application of cultivated land, its effect will be better. However, it should be noted that the application depth should be more than 6 cm (sandy soil can be deeper), and the soil should be covered immediately after application, so as to reduce the loss of nitrogen. Ammonium bicarbonate as topdressing, dry land can be combined with ploughing, to apply less than 2 inches, and immediately cover the soil, but also timely watering. The paddy field should maintain a shallow water layer of about 1 inch, but not too shallow, otherwise it is easy to hurt the roots. After application, cultivation and rake should be carried out in time to promote the fertilizer to be well absorbed by the soil. When using ammonium bicarbonate as topdressing, remember not to spread it just after the rain or before the dew is dry. Ammonium bicarbonate, whether used as base fertilizer or topdressing, should not be spread on the soil surface to prevent nitrogen volatilization, resulting in nitrogen loss or fumigation of crops. At the same time, it should be avoided in high temperature season and high temperature period, and should be applied in the season when the temperature is less than 20 ℃.

Diammonium phosphate

Diammonium phosphate is a kind of high concentration quick-acting fertilizer, which is suitable for all kinds of crops and soil, especially for crops that like ammonium and phosphorus, and should be used as base fertilizer. If it is used as topdressing, it should be applied early and 10 cm deep to cover the soil, not too close to the crop, so as not to burn the crops. When planting fertilizer, it should not be in direct contact with the seeds. Do not spread diammonium phosphate with water, otherwise it will leave most of the nitrogen on the surface, and do not mix with plant ash, lime and other alkaline fertilizers, so as not to cause nitrogen volatilization and reduce the effectiveness of phosphorus.