Efficacy of Biochar Amendments in Limiting the Transport of Pathogenic Bio-Colloids in Soils of Different Textures.

Biochar amendment has been shown to affect bacterial transport in soils. The effect of pyrolysis temperature of the added poultry litter biochar on the transport of Escherichia coli O157:H7 and Salmonella typhimurium through fine sand and sandy loam soils were investigated in water-saturated column experiments. The poultry litter biochars utilized in the study were pyrolyzed at two temperatures: 350 ^oC (low temperature) and 700 °C (high temperature). While the addition of the low temperature biochar to fine sand did not affect retention of either bacterium, amendment with the high temperature biochar significantly limited transport of both isolates.  In contrast, addition of high temperature biochar to sandy loam did not affect the transport of E. coli and increased the breakthrough of S. typhimurium. Addition of the low-temperature biochar to sandy loam facilitated the transport of both bacteria – increasing breakthrough by up to 3.5 orders-of-magnitude. These results indicate that biochar type plays an important role as some biochars may facilitate bacterial transport through soils depending on soil texture.