Sorbitol and biochar have key roles in microbial and enzymatic activity of saline-sodic and calcareous soil in millet cropping.

Strengthening the microbial and enzymatic activities of the soil can be a way to increase the resistance of the plant to saline and sodic conditions. This research aimed to study the effect of sorbitol and biochar on improving the biological and chemical properties of saline and sodic soil in a millet cropping system. The field experiment was performed in a randomized block design with a factorial arrangement in three replications in field conditions. Experimental factors include three levels of sorbitol (S0: 0 t ha−1, S1.5: 1.5 t ha−1, and S3: 3 t ha−1) and two levels of sunflower stem biochar (B0: 0 t ha−1 biochar, B: 15 t ha−1 biochar). The results showed that sorbitol (S1.5, S3) and biochar increased microbial activity (BR and MBC) and soil enzymatic activity (DHA, ALP, UA, and CAT). Sorbitol had no significant effect on soil pH but reduced soil ECe (26%, 33%) compared to without sorbitol treatment. Sorbitol and biochar increased soil available nitrogen, available phosphorus, and dissolved organic carbon. 3 t ha−1 sorbitol increased millet yield by 50% more than 1.5 t ha−1 sorbitol and 72% more than biochar treatment. According to the results, using sorbitol and biochar in saline and sodic soil increased millet yield by improving the soil's biological and chemical properties.