Saline Soils Can Be Ameliorated by Adding Biochar Generated From Rice‐Residue Waste

Abstract

Information on the effects of biochar on salinity is inadequate, although increasing data have shown that the addition of biochar can improve soil fertility and crop production. Soil samples varying in electrical conductivity (EC) levels (2 (EC2; non‐saline control), 8 (EC8), and 16 (EC16) dS m−1) collected from a long‐term field experiment on irrigation water induced salinity were incubated for 8 weeks with different rates of rice‐residue biochar (B0: unamended, B1: 1%, B2: 2%, B4: 4% w/w). Irrespective of salinity, both EC and pH increased with increasing rate of biochar application. Compared with unamended control soil (EC2), cumulative respiration (CR) and microbial biomass carbon (MBC) in EC8 or EC16 soil was lower by 39–63 and 51–71%, respectively. However, addition of biochar at the rate of 2–4% reduced the decrease in CR and MBC either to 21% or similar to unamended non‐saline treatment in EC8 soil, respectively. However, the percentage decrease in CR and MBC was reduced to 47 or 21% in EC16 soil, respectively. Contrarily, biochar addition at the rate of 1% in EC8 or EC16 soil did not show a significant increase in CR and MBC compared with non‐saline control. Furthermore, at all salinity levels, ‐N concentrations increase with increasing incubation time and biochar rates, whereas ‐N concentrations were greater on day 14 than day 56 of incubation. It may be concluded that application of higher rates of rice‐residue biochar (2–4%) will be more effective in reducing the adverse effects of salinity on soil properties.