Effect upon soil pH . Use of anhydrous ammonia and ammonia compounds will eventually have an acidifying effect on the soil. This soil acidifying action tends to bring into solution or make available some minor elements such as iron, manganese, copper, zinc, and molybdenum. This does not mean that the entire soil becomes acidic, just the area around each fertilizer particle or concentration of particles. This acidifying effect is usually of short duration.
Phosphates are generally neutral in their effect on soil pH, and potassium carriers are basic.
Form of nitrogen. The form of nitrogen applied influences directly the nutrition and growth of the plant. Most plants seem to prefer the nitrate form. Nitrate and ammonium are readily absorbed and utilized by plant roots. Under favorable conditions, ammonium nitrogen is converted to the nitrate form by nitrifying bacteria in the soil.