Makes slightly wet soils easier to till: Soils that have been treated with gypsum have a wider range of soil moisture levels where it is safe to till without danger of compaction or deflocculation. Even a liberal application of gypsum is a good procedure for starting a piece of land into no-till soil management or pasture. Gypsum also improves the ability of soil to drain and not become waterlogged due to a combination of high sodium, swelling clay, and excess water.
Stops water runoff and erosion: Gypsum improves water infiltration rates into soils and also the hydraulic conductivity of the soil. The use of gypsum can decrease wind and water erosion of soil.
Improves swelling clays: Gypsum can decrease the swelling and cracking associated with high levels of exchangeable sodium on the montmorillonite-type clays. As sodium is replaced by calcium on these clays, they swell less and therefore do not easily clog the pore spaces through which air, water and roots move.
Increases water retention in soil: Gypsum when applied to sodic soil reduced the levels of exchangeable sodium resulted in increase in water retention. The improved soil structure help in the more retention of water. Increases the stability of soil organic matter: Gypsum is a source of calcium responsible for the binding of soil organic matter to clay and gives stability to soil aggregates.
Improves low-solute irrigation water: Gypsum is used to increase the solute concentration of low-solute water used for irrigation. Irrigation water from rivers that no longer have sources of leachable salts either penetrates poorly into soil or causes soil particles to degrade which results in low-water penetration. The problem can be corrected with surface-applied gypsum or application to the irrigation water.
Improves water-use efficiency: Gypsum application increases water-use efficiency of crops. Improved water infiltration rates, improved hydraulic conductivity of soil, better water storage in the soil all lead to deeper rooting and better water-use efficiency.