Types of fertilizers and their application (6)

Ammonium nitrate Ammonium nitrate contains 33%~35% nitrogen, there are two kinds of crystalline and granular, the former is very hygroscopic, the latter is slightly weaker due to the moisture repellent attached to the surface. Ammonium nitrate contains both ammonium nitrogen and nitrate nitrogen, both of which can be absorbed and utilized by crops. Therefore, ammonium nitrate is a good nitrogen fertilizer without any residue in the soil and is a physiologically neutral fertilizer. Ammonium nitrate should be used as topdressing for dry crops, and it is more economical to apply it in small quantities. It should not be applied to paddy fields, and it should not be used as base fertilizer and seed fertilizer. Ammonium sulfate Ammonium sulfate contains 20%~21% nitrogen, pure ammonium sulfate is white crystal, ammonium sulfate used as fertilizer often has some impurities and is light green or gray. Ammonium sulfate is a physiological acid fertilizer. If it is applied in large quantities on acidic soil for a long time, it will increase the acidity of the soil. Lime and organic fertilizer should be applied. When it is applied on calcareous and neutral soil, sulfate ions combine with calcium ions to generate calcium sulfate (calcium sulfate has low solubility and is easy to block soil voids and cause soil hardening). Organic fertilizer should be applied. Ammonium sulfate is easy to be used as seed fertilizer, base fertilizer and topdressing. Ammonia water contains 15%~20% nitrogen, belongs to liquid fertilizer, is strongly alkaline, has a pungent ammonia smell and has a strong corrosive. Ammonia water is unstable and easy to volatilize. The higher the concentration, the higher the temperature, the longer the storage time and the worse the container tightness, the greater the volatilizing loss. Ammonia can be used as base fertilizer and topdressing, but it should be applied deeply in furrows and diluted several times in water, otherwise it will burn crops. Calcium nitrate contains 13%~15% nitrogen, pure calcium nitrate is white crystal, calcium nitrate used as fertilizer is gray or light yellow particles, it is easy to absorb moisture, it is easy to deliquesce and autolysis in the air, and should be sealed during storage and transportation. Calcium nitrate is suitable for a variety of soils and crops, because it contains 19% water-soluble calcium, especially for vegetables, fruit trees, peanuts, tobacco and other calcium-loving crops. Care should be taken to avoid nitrate ion loss when applying calcium nitrate. Calcium superphosphate contains available phosphorus (phosphorus pentoxide)14%~20%, generally gray or light yellow powder. The secondary component of calcium superphosphate is anhydrous calcium sulfate, accounting for about 50% of the total amount, and contains 3% to 5% of free acid and secondary iron phosphate, aluminum phosphate and other compounds. Calcium superphosphate is a physiological acid fertilizer, there is a certain moisture absorption caking, in the storage process, pay attention to moisture, generally stored should not exceed one and a half years. Calcium superphosphate is suitable for all kinds of soil and crops, and can be used as base fertilizer, topdressing and foliar fertilizer.