Gypsum is one of the first fertilizers used by farmers throughout the world. In some places it has been used as a fertilizer for about 250 years. Gypsum has moderate solubility in water (2.5-2.6 g/L). Its solubility is much greater compared to compounds such as lime but much lower in comparison with substances including chlorine and calcium. The moderate solubility of gypsum makes it possible to satisfy the needs of plants for calcium and sulfur by applying gypsum to soil. Moreover, its moderate solubility prevents soil salinization when it is applied to soil whereas provision of these nutrients, or other necessary nutrients, by applying more soluble fertilizers will cause soil salinity.
Effects of agricultural gypsum on agricultural soils
The effects of gypsum on agricultural soils can be divided into three groups: (1) its effects on soil physical properties, (2) its effects, as a fertilizer, on plant nutrition and (3) its effects as an amendment for problematic soils (sodic soils, acid soils and clay soils)
The main goals in agricultural operations are management of the available soil and water and the air in soil in a way that plant roots can reach their maximum genetic growth potential. Under these conditions, they can absorb the largest amounts of water and nutrients and hence crops will be able to produce their maximum yield per hectare. Consequently, desirable soil physical properties are one of the most important factors in obtaining the maximum possible crop yields. If soil physical properties are not suitable for plant growth, use of fertilizers and nutrient solutions will have little effect on crop yield. Although even a small change made in soil physical properties increases efficiency of chemical fertilizers, this important point is often ignored by farmers who often seek to increase yield only by applying fertilizers and nutrient solutions to soil. Gypsum is one of the important amendments for soil physical properties and substantially increases crop yield.