Effect of Selenium-Enriched Biochar on Some Chemical Properties of Calcareous Soil Under Salinity Stress

A basic solution to reduce the harmful effects of salinity stress is to apply biochar, which can be improved by modifying and enriching it. For this purpose, a completely randomized design experiment with three replications was conducted with treatments including salinity (2 and 6 dS/m) and biochar prepared from landscape waste at four levels (zero and 5% without enrichment, 5% enrichment with selenium at the rate of 20 and 60 mg/kg). Biochar enrichment decreased soil pH. Enriched biochar at the level of 60 mg/kg increased soil salinity. The amount of soil organic carbon increased proportionally by increasing biochar. The lowest amount of phosphorus was observed in the treatment of saline soil without biochar at the rate of 2.47 mg/kg, and the highest amount was observed in the treatment of non-saline soil containing 5% enriched biochar at the level of 60 mg/kg at the rate of 3.55 mg/kg. The amount of available potassium showed an increasing trend with increasing salinity levels. Enriching biochar with selenium reduced the positive effects of biochar on increasing the amount of potassium, especially in saline soil. In non-saline soil, biochar enrichment increased soluble sodium by 16.6% compared to non enrichment biochar, and increasing the level of enrichment did not show a significant effect. The change in the amount of solutes in the soil changed its chemical characteristics, and these changes were manifested in different ways under the influence of biochar and the level of enrichment.