ABSTRACT
Gypsum occurs naturally in mineral form and is a by-product of various industrial processes. It has been used for many years as a soil conditioner for sodic and heavy clay soils, as a nutrient source of Ca and S for plant growth, and more recently as an ameliorant for the subsoil acidity syndrome. For centuries, naturally occurring mineral gypsum has been mined for use in agriculture. These deposits have usually resulted from precipitation during the evaporation of inland seas. The use of lime has proved to be highly effective in overcoming acidity in surface soils, but the high costs of incorporation and the fact that it does not move readily down the profile have made it unsuitable for subsoil acidity amelioration. Gypsum (mined and by-product) is by far the most commonly used amendment for maintaining adequate hydraulic properties in sodic soils because of its low cost, availability, and ease of handling.
