Chromium (Cr) contamination in farmlands has become a serious environmental concern due to the excessive use of industrial wastewater as an irrigation source. Therefore, some important measures need to be taken for reducing its mobility in a soil profile. A pot study was conducted to evaluate the effectiveness of sugarcane bagasse derived biochar and acidified manure on Cr mobility and its uptake by maize plant. Results showed that the application of biochar and acidified manure significantly changed soil pH, improved crop growth and as well as reduce the antioxidant response of maize in Cr contaminated soil. The concentration of bioavailable (AB-DTPA) extractable Cr in soil decreased with the addition of co-use of biochar (3%) and acidified manure (5%) by 36% relative to control. The maximum reduction in superoxidase dismutase (SOD), peroxidase dismutase (POD), and catalase activity assay (CAT), and ascorbate peroxidase activity (APX) was occurred by 41%, 51%, 20%, and 55%, respectively when biochar (3%) amended with the combination of acidified manure in Cr contaminated soil. Among all the amendments, biochar at 3% application combination with acidified manure (B2 + AMS) offered significantly minimize Cr mobility (Cr-III (44%) and Cr-VI (22%)) and thereby reduce its uptake by maize plant.

In the present study, we investigated the impact of different combinations of wheat straw biochar, compost and biogas slurry on maize growth, physiology, and nutritional status in less productive soils. The experiment was performed as a completely randomized block design in a greenhouse pot experiment. The compost and biogas slurry were applied with and without biochar. The results revealed that a combination of biochar, compost, and biogas slurry enhanced the cation exchange capacity (31%), carbon (83%), phosphorus (67%) and potassium (81%) contents in the soil. Likewise, a significant increase in soil microbial biomass carbon (15%) and nitrogen (37%) was noticed with the combined use of all organic amendments. Moreover, the combined application of biochar, compost and biogas slurry enhanced soil urease and β-glucosidase activity up to 96% and 67% over control respectively. In addition, plant height, chlorophyll content, water use efficiency and 1000-grain weight were also enhanced up to 54%, 90%, 53% and 21% respectively, with the combined use of all amendments. Here, biochar addition helped to reduce the nutrient losses of compost and biogas slurry as well. It is concluded that biochar application in combination with compost and biogas slurry could be a more sustainable, environment-friendly and cost-effective approach, particularly for less fertile soils.