Environmental association with plant

In plant, substantial amounts of nutrients are removed from the soil during their normal growth cycle and many long-term environmental changes occur as a result of this process. Charge balance must be maintained in the plant-soil system during nutrient uptake. Charge balance is usually achieved by the excretion of proton or hydroxyl ions by the plant to replace the absorbed nutrient cations. When plants are fertilized with ammonia, they acquire most of their nitrogen in the form of the ammonium cation, rather than from the usual nitrate anion. However, because nitrate is the only anion used by the plant in large amounts, the net result of this change is that during normal nutrient uptake the proton excretion will far exceed that of hydroxyl ions, while in the case of vigorously growing plants, the amount of excreted protons can be sufficiently large as to decreasing of the pH of the soil by several pH units. Changes in soil pH of such magnitude can have large implications for a number of soil processes such as soil structure, nutrient availability and leaching of nutrients.

The immediate effect on the soil may be favorable for some plants, most especially which of acid-loving plants, in that it tends to make iron more available. However, in the long run, lowering the soil pH can be deleterious to plants in that the availability of nutrients. A lower soil pH will allow micronutrients to be more readily leached from the soil profile, eventually resulting in deficiencies of nutrients such as Cu and Zn