Influence of alfalfa residue and different-source biochars on the chemical properties of a saline-sodic soil

A pot experiment was done aimed to improve the chemical properties of a saline-sodic soil using individual application of alfalfa residue and two biochars, produced from sugarcane bagasse and walnut shell and their concomitant application with gypsum, aluminum sulfate and mixture of these two chemical amendments. Organic and chemical amendments were added to the soil at the weighting ratio of 2.5% and as the soil gypsum requirement, respectively. After two months of incubation, soil samples were measured for soil pH, electrical conductivity (EC) and sodium adsorption ratio (SAR) and the results were analyzed by SPSS software applying ANOVA. The results showed that organic amendments caused a reduction in soil pH and enhanced soil EC and SAR; whereas addition of gypsum and/or aluminum sulfate with biochars intensified their regulatory effects. It can be concluded that application of walnut-shell biochar with mixture of gypsum and aluminum sulfate to the saline-sodic soils has the best efficiency to reclaim the chemical soil properties. Soil leaching, as a supplementary procedure, however, is necessary to complete the improving effects of organic and/or chemical application to the soil.