Submitted to: Journal of Environmental Quality
Publication Type: Peer reviewed journal
Publication Acceptance Date: 12/2/2013
Publication Date: 1/5/2014
Publication URL: http://handle.nal.usda.gov/10113/58653
Citation: Abit, S.M., Bolster, C.H., Cantrell, K.B. 2014. Transport of Escherichia coli O157:H7 and Salmonella typhimurium in biochar-amended soils with different textures. Journal of Environmental Quality. 43:371-378. Interpretive Summary: Biochar is a charcoal-like material generated during the thermal degradation of organic matter in the absence of air. The incorporation of biochars into soil has been suggested as an effective means of sequestering carbon and recent research has demonstrated the potential of using biochar for enhancing soil-retention of agrochemicals, heavy metals, and excess nutrients. Recent studies have also shown that addition of biochars can significantly modify transport behavior of E. coli in soils. These studies with bacteria, however, only utilized sandy soils with very minimal clay content. In this study, we compare the effects of biochar addition on bacterial transport using two soils: a fine sand with less than 1 % clay and a sandy loam with 12.5 % clay. Our results show that soil texture does affect the relative benefit of the applied biochars in limiting the transport of bacteria in soil. Indeed, in contrast to the fine sand where biochar amendments generally increased cell retention, bacterial retention in the sandy loam decreased significantly for several of the biochar treatments.
Technical Abstract: Biochar amendment has been shown to affect bacterial transport in soils. The effect of soil texture on the transport of Escherichia coli O157:H7 and Salmonella enterica serovar Typhimurium in soils amended with 2 % poultry litter or pine chip biochars pyrolyzed under two temperatures (350 and 700 'C) was evaluated in water-saturated column experiments. Adding poultry litter biochar pyrolyzed at 350 oC did not improve soil-retention of either bacteria in fine sand and even facilitated their transport in sandy loam. Addition of either biochar pyrolyzed at 700 oC generally improved retention of both bacteria in fine sand with the pine chip biochars being more effective in limiting their transport. The influence of biochar amendment in increasing retention of both bacteria was generally more pronounced in fine sand. Higher fraction of finer separates in sandy loam seems to have a normalizing effect over the possible contribution of applied biochars on retention of E. coli and S. typhimurium. This suggests that soil texture does affect the relative benefit of the applied biochars in limiting the transport of these bacteria in soils.