Biochar additions across Illinois agricultural soils: Greenhouse gas production, corn growth, and soil microbial responses

Authors: MESCHEWSKI, ELIZABETH - University Of Illinois; HOLM, NANCY - University Of Illinois; SHARMA, BRAJENDRA - University Of Illinois; Spokas, Kurt; MINALT, NICOLE - Loyola University; KELLY, JOHN - Loyola University

Submitted to: Chemosphere
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/1/2019
Publication Date: 8/1/2019
Citation: Meschewski, E., Holm, N., Sharma, B., Spokas, K.A., Minalt, N., Kelly, J. 2019. Biochar additions across Illinois agricultural soils: Greenhouse gas production, corn growth, and soil microbial responses. Chemosphere. 228:565-576. https://doi.org/10.1016/j.chemosphere.2019.04.031.
DOI: https://doi.org/10.1016/j.chemosphere.2019.04.031

Interpretive Summary: Biochar is a promising soil amendment that has linked to several soil quality improvements. However, these benefits are not always realized and we are lacking guidance on biochar use. We tested 11 different soil types and 5 biochar additions to these soils across greenhouse gas production tests, plant growth, seedling emergence, and soil microbiology assessments. Results indicated that plant growth, net GHG production potentials, and soil microbial community structure were not significantly impacted by any of the thermal pyrolysis biochars from different feedstocks at 1 and 5% (w/w). On the other hand, both an open-air burned corn stalk biochar and raw corn stover feedstock did alter the observed soil functionality. Therefore, this research suggests that thermal pyrolytic biochar represents a stabilized form of carbon that is resistant to microbial mineralization and has negligible effects on plant growth, biomass production, or microbial community structure. These results are significant to farmers and policy makers and will assist scientists and engineers in understanding the potential pathways for mechanisms for biochar to improve carbon sequestration.

Technical Abstract: Biochar has been promoted as a soil amendment that enhances soil quality and agronomic productivity and reduces greenhouse gas production. However, these benefits are not always realized. A major hurdle to the beneficial use of biochar is our limited knowledge regarding the mechanisms directing its effects on the soil system. This project aimed to eliminate some of this uncertainty by examining the responses of a suite of soils (11 different soil types) to the addition of biochars produced from a range of feedstock materials (corn stalks, hardwood, and grass based) by different processes (pyrolysis, gasification, and burning). Specifically, this study assessed the impacts of the biochar amendments on plant productivity, greenhouse gas production, and soil microbial community structure. Results indicated that plant growth, net GHG production potentials, and soil microbial community structure were not significantly impacted by the addition of thermal pyrolysis biochars from different feedstocks at 1 and 5% (w/w). On the other hand, both an open-air burned corn stalk biochar (5% addition level) and raw corn stover feedstock (both 1 and 5% levels) did alter the observed soil functionality. For example, the 5% burnt biochar addition reduced total above ground plant biomass (~40%), increased observed N2O production by an order of magnitude, and altered soil bacterial community structure. The bacterial groups that increased in relative abundance in the soils amended with the burnt biochar included families associated with cellulose decomposition (Chitinophagaceae), plant pathogens (Xanthomonadaceae), and biochar and charcoal amended media (Gemmatimonadetes). In contrast, the abundnace of these bacterial groups was not impacted by the thermal pyrolysis biochars. Therefore, this research suggests that thermal pyrolytic biochar represents a stabilized form of carbon that is resistant to microbial mineralization and has negligible effects on plant growth, biomass production, or microbial community structure.