Application of biochar and compost improved soil properties and enhanced plant growth in a Pb-Zn mine tailings soil

This study evaluated the effect of biochar and compost on physiochemical properties, heavy metal content, microbial biomass, enzyme activities, and plant growth in Pb-Zn mine tailings. In this study, a pot experiment was conducted to evaluate the effects of biochar, compost, and their combination on the availability of heavy metals, physicochemical features, and enzyme activities in mining soil. Compared to separate addition, the combined application of biochar and compost was more effective to improve soil pH, soil organic carbon (SOC), total nitrogen (TN), available phosphorus (AP), and potassium (AK). All amendments significantly decreased CaCl2-extractable Pb, Zn, Cu, and Cd. Soil enzyme activities were activated by biochar and compost. Meanwhile, the addition of biochar and compost decreased heavy metal content in plant tissues and increased plant biomass. Pearson's correlation analysis showed that plant biomass was positively correlated with nutrient levels, microbial biomass, and enzyme activities, whereas it was negatively correlated with CaCl2-extractable heavy metals. These results enhance our understanding of the ecological functions of biochar and compost on the restoration of mining soil and reveal the potential benefit of organic amendments on the improvement of mining soil quality.

Automated summary

This study evaluated the effects of biochar and compost on various aspects of Pb-Zn mine tailings, including physiochemical properties, heavy metal content, microbial biomass, enzyme activities, and plant growth. The combination of biochar and compost was found to be more effective than separate addition in improving soil pH, organic carbon content, nitrogen content, phosphorus availability, and potassium availability. Both biochar and compost also decreased heavy metal content in soil and plant tissues, while increasing plant biomass. These findings contribute to our understanding of the ecological functions of biochar and compost in mining soil restoration and highlight the potential benefits of organic amendments in improving mining soil quality.