What effects does gypsum have on soil?
Gypsum is a soil conditioner on sodic soils. In those situations, the Ca from the gypsum displaces the sodium and allows the sodium to leach out. Gypsum is basically a neutral salt, the salt of a strong acid (sulfuric acid) and a strong base (calcium hydroxide). As a result, it has little impact on soil pH per se. Theoretically, gypsum will neither raise nor lower pH. On sodic soils, it will lower pH as the sodium will get flushed from the system. On acid soils, it may tend to give a slight increase in ph.
