However, Kelly et al. (2014) could not find any
changes in microbial population or activity in mining
waste upon biochar application. Therefore, the characteristics
of the substrate to be treated are crucial for
the biochar selection. Biochar has turned a wasteland
enriched with As, Cd, Pb, and Zn on a steep mountainside
into a haven for natural grasses and wildflowers
that have stabilized the slope and almost diminished
the risk of heavy metal leaching into the city’s main
water supply around Hope Mine (Fig. 2).