Biochar and earthworms synergistically improve soil structure, microbial abundance, activities and pyraclostrobin degradation

As a widely used fungicide, the toxic impacts of pyraclostrobin on soil ecosystems have attracted extensive concern. Thus, it is very important and meaningful to develop effective strategies to alleviate its toxic effects. Therefore, in this study, we used corn straw-derived biochar produced at 500 degrees C as a soil amendment to study its effects on soil microbial populations, aggregation, enzymatic activities, and earthworm Eisenia fetida in pyraclostrobin-contaminated soil. Our results showed that biochar application (1%, w/w) significantly (Tukey test, p < 0.05) increased microbial abundance (culturable fungi, bacteria, actinomycetes), enzyme activities (urease, invertase, and dehydrogenase), and the formation of soil macroaggregates (>0.25 mm). Moreover, biochar application eliminated the toxic effects of pyraclostrobin on soil microorganisms and reduced oxidative stress and DNA damage in E. fetida by increasing the dissipation of pyraclostrobin in soil. We also found that biochar and earthworms synergistically improved the soil structure and degradation of pyraclostrobin, thus indicating that the combined application of biochar and earthworms is a better strategy to improve soil physical structure, biological properties, and health. Finally, we conclude that increasing the soil food web and physical complexity by adding biochar and earthworms may improve soil health stressed by xenobiotic pollutants.