Common types and characteristics of nitrogen fertilizers
1. Ammonium nitrogen fertilizers: include ammonium sulfate, ammonium chloride, ammonium bicarbonate, and ammonia water, etc.
Characteristics: Easily adsorbed by soil colloids and less prone to loss; decompose easily in alkaline conditions, releasing ammonia gas and causing loss; excessive concentration can be toxic to crops.
2. Nitrate nitrogen fertilizers: include sodium nitrate, potassium nitrate, and ammonium nitrate, etc.
Characteristics: Easily soluble in water, with good quick-release properties; highly hygroscopic, prone to caking; mobile in soil, easily lost with water; in anoxic conditions, nitrate will undergo denitrification, resulting in nitrogen loss.
3. Amide nitrogen fertilizers: mainly urea.
Characteristics: High nitrogen content, being the fertilizer with the highest nitrogen content among solid nitrogen fertilizers; easily soluble in water, with slightly slower fertilizer efficiency compared to ammonium and nitrate nitrogen fertilizers, but longer duration; requires microbial action in the soil to convert into ammonium nitrogen before being absorbed and utilized by crops.
Scientific use methods of nitrogen fertilizers
1. Select according to crop types: Different crops have different requirements and absorption capabilities for nitrogen. Leafy vegetable crops (such as cabbage, spinach, etc.) have a higher demand for nitrogen and should be given more nitrogen fertilizer; legume crops (such as soybeans, peanuts, etc.) can fix nitrogen from the air through rhizobia and have relatively lower demand for nitrogen fertilizer.
2. Determine the application amount based on soil fertility: In fertile soil, the application amount of nitrogen fertilizer can be reduced; in poor soil, the application amount should be increased.
3. Master the appropriate application period: Generally, crops have higher demands for nitrogen during the seedling stage and vigorous growth period, so timely fertilization should be carried out. For example, rice needs more nitrogen fertilizer during the tillering stage, wheat during the jointing stage, and corn during the large ear stage.
4. Adopt the correct application method:
Deep application and covering with soil: Apply nitrogen fertilizer to the deep layer of the soil (generally 10-15 centimeters) and cover it with soil to reduce volatilization and loss.
Multiple applications: According to the growth needs of the crop, apply nitrogen fertilizer in several doses to avoid waste and pollution from excessive application.
Combined irrigation fertilization: Dissolve nitrogen fertilizer in water and apply it to the soil during irrigation, which can increase the utilization rate of nitrogen fertilizer.
