The effect of water soluble polymer, modified starch and nano clay with and without gypsum and aluminum sulfate on dispersible clay percentage in a sodic soil

Land salinization and sodification is a serious problem for being human in arid and semiarid regions of the world. Salt affected soils are widely distributed in Iran and this study is aimed to assess the ameliorative effects of different materials for reclamation of sodic soils. In order to study the effects of gypsum and aluminum sulfate alone or with water soluble polymer, modified starch, nano clay and a combination of these materials on physical properties of a sodic soil, a factorial experiment with 18 treatments was conducted in Zanjan University using a completely randomized design and three replications. After addition of different treatments to soil samples, they were incubated for four months at moisture content of field capacity. The results of the experiment showed that the effects of gypsum, aluminum sulfate, modified starch, water soluble polymer with nano clay were significant on reducing dispersible clay content. The lowest amount of dispersible clay was measured in treatment with 75 kg ha-1 water soluble polymer + 75 kg ha-1 modified starch + 2% nano clay and along with aluminum sulfate equivalent to gypsum requirement of the soil. This treatment reduced the amount of dispersible clay from %95 in control to %3.4. In contrast, the highest amount of water dispersible clay was shown in control treatment.