Copper (Cu) contamination in soils, particularly in areas where Cu-based fungicides are heavily used, poses significant environmental risks. Elevated Cu levels can harm ecosystems, plant life, and human health. One proposed solution is the use of biochar to mitigate Cu accumulation in plants, though there is limited quantitative data on its effectiveness.

This meta-analysis examines 624 data records from 65 studies to evaluate how biochar affects Cu accumulation in plants. The findings show that biochar application can reduce Cu concentration in plants by an average of 23.45%, with the impact being dose-dependent. Certain soil conditions—acidic pHpH is a measure of how acidic or alkaline a substance is. A pH of 7 is neutral, while lower pH values indicate acidity and higher values indicate alkalinity. Biochars are normally alkaline and can influence soil pH, often increasing it, which can be beneficial More and medium-textured soils—were found to enhance biochar’s effectiveness in reducing Cu uptake.

Among biochar types, manure and green waste biochar were the most successful at decreasing Cu concentrations. Biochar produced at pyrolysisPyrolysis is a thermochemical process that converts waste biomass into bio-char, bio-oil, and pyro-gas. It offers significant advantages in waste valorization, turning low-value materials into economically valuable resources. Its versatility allows for tailored products based on operational conditions, presenting itself as a cost-effective and efficient More temperatures above 600°C and with pH levels of 10 or higher were also found to be more effective. Recommended application rates include at least 1% biochar in potting experiments and 20 tons per hectare in field applications.

These findings provide important insights for reducing Cu transfer through the food chain and offer guidance for policymakers on mitigating soil Cu contamination. Biochar presents a promising strategy for managing soil contamination and protecting both environmental and human health.