Adverse Impact of Sodicity on Soil Functions can be Alleviated through Addition of Rice Straw Biochar

Beneficial effects of biochar on physicochemical properties in non-saline and non-sodic soils have been widely acknowledged. However, information is inadequate regarding potential of using rice straw derived biochar as an organic material to reduce sodicity stress. Soil samples varying in sodicity (SAR – Sodium Adsorption Ratio) levels [SAR2.5 (control), SAR20 and SAR30], collected from long-term field experiment were incubated for 8 weeks with different rates of rice straw biochar (B0: control, B1: 1%, B2: 2%, B4: 4% w/w). Carbon mineralization was adversely affected by sodicity, far greater in SAR20 than SAR30 soil. Irrespective of the SAR levels, addition of rice straw biochar enhanced cumulative respiration (CR) and microbial biomass carbon (MBC), more so at higher rate of application. Both pH and SAR significantly decreased in the biochar amended sodic soils, whereas opposite trend was noticed in the amended control. Furthermore, at all SAR levels, NO3–N concentrations were greater at differential biochar rates on day 14 and 56 of sampling; however, the results were contrary as far as NH4+-N was concerned. It may be concluded that rice straw biochar can be used as an organic amendment for reducing adverse effects of sodicity on soil functions governed by their rate of addition.