Salt

A chemical compound with negative and positive ions, producing a net zero electrical charge for the material. Soils with a high salt concentration, which can arise immediately after the application of a fertiliser, where applied at a high rate and where soil moisture becomes limited, can inhibit plant growth by reducing water uptake and effectively drying out the plant, including root shrinkage.

Whilst common salt (Sodium chloride - NaCl from the combining of the ions Na+ and Cl-) is often first considered as what is meant by salt, especially in coastal soils, any combination of elements and molecules to form compounds are salts. The net zero electrical charged ammonium sulphate ((NH4)2SO4)) is a combination of ammonium (NH4+) and sulphate (SO4-2).