Effects of Biochar and Microbial Organic Fertilizers on Agricultural Productivity and Their Microbial Mechanisms Under Heavy Metal Stress.

Biochar has been demonstrated to be effective in the remediation of heavy metal contamination in soil. However, few studies have examined the impacts of varying proportions of biochar and microbial organic fertilizers on heavy metal adsorption and microbial abundance in soil. Therefore, we investigated the remediation of soil contaminated with heavy metals (Cd and Cu) using different proportions of biochar and microbial organic fertilizer. The results revealed that the adsorption effect of different modifier combinations on heavy metals was notably different, and the metal speciation was significantly altered. Optimal biochar and microbial organic fertilizer combinations significantly reduced the bioavailability and ecological toxicity of heavy metals in the soil, which enhanced plant germination and growth. Furthermore, the addition of modifiers regulated soil pH, preventing root acidification; optimized microbial abundance; enhanced soil microbial environment; and reduced the inhibitory effect of heavy metals on microorganisms. These findings indicate that the addition of amendments may create a virtuous cycle of heavy metal pollutant adsorption, resulting in organic fertilizer efficiency, a better soil environment, and increased crop yield.