Assessment of the Impact of Organic and Chemical Amendments on some Chemical Indicators of Saline-Sodic Soils

In the current study, the effect of organic (vermicompost and biochar) and chemical (gypsum and elemental sulfur) amendments and combination of vermicompost and chemical treatments on the possibility of improving a saline-sodic soil was investigated. The experiment was conducted using a completely randomized design with three replications in a greenhouse condition. After mixing with different treatments, soil samples were kept in the field capacity for 120 days and then some of the most important chemical and nutritional properties of the soils were determined. The results showed that vermicompost caused a significant decrease in soil pH compared to the control treatment and its combination with elemental sulfur was the most effective treatment in improving pH (a drop of 0.75 to 0.95 unit in soil pH). All treatments significantly increased soil EC and SAR compared to the control treatment by increasing the concentration of soluble salts (such as Ca+2 and Mg+2) and replacing some of these ions with soil exchangeable Na. Among the treatments, vermicompost and gypsum had the greatest impact on EC and SAR by an increase of 2.8 to 3.8 dS m-1 in EC and 8.6 to 9.3 units in SAR. While available P, Fe, and Zn significantly increased by the direct release of nutrients from organic compounds and the improvement of soil chemical conditions following using the combination of organic (vermicompost) and chemical treatments, the individual chemical treatments had little effect on the improvement of elements. Overall, the combined application of chemical and organic treatments (vermicompost) more effectively than individual treatments has improved the unfavorable chemical conditions of saline-sodic soil and increased its fertility.