However, if the concentration of any soluble salt in the soil, including those from fertilizers, becomes too high, the roots and later the plant tops are injured. In this case, the soluble salts enter the roots and are moved through the plant vessels to the leaves where the water evaporates and gradually concentrates the salts to toxic levels. When soil soluble salts are excessively high, the roots are unable to absorb water and the plant wilts. The problem is apt to be more pronounced after fertilizing, or during excessively dry conditions. This may occur naturally after a rain, or be alleviated by irrigation.
Some plants are more prone to salt injury than others.
Examples of easily damaged plants are, peanut, soybean, corn, alfalfa, clovers, timothy and vetch. How to Avoid High Salt Injury 1. Use the correct amount of fertilizer of the proper analysis. High analysis fertilizers have less salt problems per unit of plant food than low analysis fertilizers. The salt index of sodium nitrate is 100 while the salt index of ammonium nitrate is 104.