Speakers - 2026

Title: Integrating bioenergy by-products into acidic soils to improve soybean growth: Physiological and biochemical mechanisms

Abstract

Soil acidification, intensified by aluminum (Al) and manganese (Mn) toxicity, severely limits crop productivity and threatens global food security. Conventional remediation methods are often costly and environmentally risky, prompting the search for sustainable alternatives. Bioenergy by-products, including bottom ash (BA), biogas slurry (BS), and biochar (BC), are alkaline-natured materials that show promise for reclaiming acidic soils, yet the underlying physiological, biochemical, and microbial mechanisms remain poorly understood. This study examined the individual and synergistic effects of BA, BS, and BC on soybean (Glycine max) grown in acidic soil through a pot experiment with eight treatments: T1 (control), T2 (BS), T3 (BA), T4 (BC), T5 (BS+BA), T6 (BS+BC), T7 (BA+BC), and T8 (BC+BA+BS). The combined application (T8) significantly increased plant height, stem diameter, leaf area, and dry matter by 40%, 101%, 72%, and 165%, respectively, compared to T1, alongside improved photosynthesis, chlorophyll content, and yield-related traits. Soil quality improved through elevated PH, organic matter, urease, Beta-glucosidase, and alkaline phosphatase activities, while bacterial diversity (Proteobacteria, Firmicutes, Actinobacteria) flourished over archaeal communities. Bioenergy by-products mitigated oxidative stress by lowering MDA and H2O2, enhancing antioxidant enzymes (SOD, POD, CAT), and upregulating photosynthesis (GmRbcS, GmRCAa, GmRCABeta) and antioxidant (GmSOD, GmPOD1, GmCAT1) genes. Nutrient uptake increased substantially (N: 124%, P: 92%, K: 116%), while heavy metal accumulation (Cr, Ni, Cu, Zn, Pb, Cd) decreased through chelation and adsorption. These findings establish bioenergy by-products as a cost-effective, sustainable strategy for reclaiming acidic soils and enhancing crop productivity in acid-prone regions.

Keywords: Acidic soil; Bioenergy by-products; Soybean; Antioxidants; Microbial diversity.