Chemical fertilizers can be divided into several categories according to their chemical properties

1. Physiological acid fertilizer. In the aqueous solution of chemical fertilizers, forage grass absorbs too many cations of the fertilizer, and the remaining anions generate corresponding acids, which make the solution acidic. Most of the ammonium and potassium salts belong to this type of fertilizer.
2. Physiological alkaline fertilizer. If the anions absorbed and utilized by the forage grass are faster than the cations absorbed and utilized, the cations in the soil solution will be excessive, and corresponding alkaline compounds will be generated to make the solution alkaline. For example, calcium nitrate and magnesium nitrate are all alkaline fertilizers.
3. Physiologically neutral fertilizers. Forage grass absorbs anions at roughly the same rate as cations, and the soil solution is neutral, such as potassium nitrate, ammonium nitrate, and urea. According to the composition of nutrients, chemical fertilizers can be divided into: nitrogen fertilizers, phosphate fertilizers, potassium fertilizers, compound fertilizers, trace elements, etc. According to the use, chemical fertilizers can be divided into: base fertilizer and top dressing.
In addition, chemical fertilizers can be divided into quick-acting fertilizers, slow-acting fertilizers and long-acting fertilizers. Soil fertilizer, foliar fertilizer, etc.