Impact of biochar with different organic materials on carbon fractions, aggregate size distribution, and associated polysaccharides and soil moisture retention in an arid soil

Biochar and organic amendments manipulate numerous soil properties but limited research has been done on the combined effect of biochar and different organic materials in an arid soil. The current study focuses on the distribution of dry soil aggregate size and associated polysaccharides by the application of biochar and its combination with other organic amendments. The treatments were the following: (i) control, (ii) biochar, (iii) poultry litter, (iv) sugarcane bagasse, (v) crop residue, (vi) biochar + poultry litter (B + PL), (vii) biochar + sugarcane bagasse (B + SB), and (viii) biochar + crop residue (B + CR). Amendments were applied on 1% total organic carbon based on soil weight. Mung bean (Vigna radiata L.) crop was sown as a test crop. The highest total organic carbon (TOC) was in biochar and crop residues (11.42 g kg⁻¹ and 11.04 g kg⁻¹ respectively); POC highest stocks were also under the same combination with similar quantity (3.80 g kg⁻¹ and 3.80 g kg⁻¹ respectively). The MBC stocks (0.25 g kg⁻¹) were highest in biochar along other combinations. In organic amendments, poultry litter produced relatively higher macroaggregation than other treatments. Polysaccharides contents had the following incremental trend: sugarcane bagasse > biochar + sugarcane bagasse > poultry litter > biochar + crop residue > crop residue alone > biochar + poultry residue > biochar > control. The highest digest plant available moisture content (θ_AMC) 14.3% was recorded in the biochar applied with the combination of sugarcane bagasse. However, the highest plant biomass (61.33 g) was in biochar + poultry litter and plant height (37.67 cm) was in biochar. Overall biochar application with crop residues is effective in improving the carbon fractions and its combination with sugarcane bagasse improves polysaccharides and soil moisture content in the arid soil.