Wednesday 22 June 2011

Biochar needn't be harmful to earthworms

Studies have found that biochar, added to the soil to help sequester carbon dioxide by removing it from the atmosphere, needn't be harmful to earthworms as had previously been thought. According to the report this emerging tool for combating climate change may cause less harm to some soil animals than initial studies suggested.

Earthworms perform many essential and beneficial functions in the soil ecosystem, including soil structure improvement and nutrient mineralization. However the earthworms' ability to perform these crucial functions can be suppressed when they are exposed to toxic substances.

Researchers and scientists from Baylor and Rice Universities, both in Texas, studied the effects of biochar on the common earthworm. The researchers found that wetting the biochar before applying it to the soil mitigates the harmful effects of biochar to earthworms and the earthworms' avoidance of soil with biochar.

"Because of the high potential for widespread application, it is essential to proactively assess and mitigate any unintended consequences associated with biochar soil enrichment," said study co-author Dr. Bill Hockaday, assistant professor of geology at Baylor. "The results show us that depending on rainfall patterns and irrigation, wetting biochar either before or immediately after soil application would be needed to prevent the disappearance of earthworms and enable their beneficial effects on plants."

The results appeared in the June issue of the journal Soil Biology and Biochemistry.