Analytical and laboratory evaluation of the solubility of gypsiferous soils

Gypsum soil is one of the problematic soils because of considerable solubility for gypsum particles in contact with water. In this research, the effects of three factors including; gypsum percent, hydraulic gradient, and soil texture were studied on solubility of gypsum soils. To do this, samples of gypsum soils were provided artificially by adding various rates of natural gypsum rock including 0, 5, 10, 20 and 30 percent by weight of 3 kinds of soil textures including clay, silty clay and sand. Totally, 15 types of gypsum soils were prepared. Then each of gypsum soils were leached under five hydraulic gradients levels 0.5, 1, 2, 5 and 10. The results of the test indicated that the rate of gypsum in the soil has direct effect on the rate of soluble in a way that by increasing percent of gypsum the rate of solubility was increased. in addition, by increasing hydraulic gradient, the speed of water outcome and its amount from soil environment in a specified time was increased and also more rate of gypsum was derived. The statistical results show the highest impact of gypsum percentage and lowest impact of hydraulic gradient soil on solubility of particles in different types of soils and it has no significant effect on the overall equation of the soil texture.