|CHINTALA, RAJESH - South Dakota State University|
|SCHUMACHER, THOMAS - South Dakota State University|
|KUMAR, SANDEEP - South Dakota State University|
|MALO, DOUGLAS - South Dakota State University|
|RICE, JAMES A - South Dakota State University|
|BLEAKLEY, BRUCE - South Dakota State University|
|CHILOM, GABRIELA - South Dakota State University|
|CLAY, DAVID - South Dakota State University|
|JULSON, JAMES - South Dakota State University|
|GU, ZHENG RONG - South Dakota State University|
Submitted to: Journal of Hazardous Materials
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/27/2014
Publication Date: 7/26/2014
Citation: Chintala, R., Schumacher, T.E., Kumar, S., Malo, D.D., Rice, J., Bleakley, B., Chilom, G., Clay, D.E., Julson, J.L., Papiernik, S.K., Gu, Z. 2014. Molecular characterization of biochars and their influence on microbiological properties of soil. Journal of Hazardous Materials. 279:244-256.
Interpretive Summary: Biomass has been identified as bioenergy feedstock to produce bio-oil and syngas as alternative renewable energy resources, producing biochar material as a byproduct. Studies have shown that applying biochar to soil can improve certain properties by influencing biochemical and biological processes in soil. We evaluated the effect of biomass conversion process on biochar’s surface chemical properties and soil biological processes. In this study, the surface chemistry of biochar materials varied with the biomass feedstock type and conversion process. Short-term incubation studies with biochars showed a negative effect on soil microbial and enzyme activity. Overall the responses of mineralization, microbial, and enzymatic activity were dependent on (1) the proportions of carbon, nitrogen, and sulfur in the biochar and (2) the properties of the soil to which it was applied. This study provides information connecting biochar surface chemistry and its influence on soil enzymatic activity and mineralization of plant nutrients. Scientists, engineers, and extension personnel can use this information to recommend practices to use biochar as an amendment to influence soil properties affecting crop production.
Technical Abstract: The composition and surface chemistry of carbon rich biochar materials is highly uncertain and believed to change with feedstock and biomass conversion process. The tentative connection between the biochar surface chemical properties and their influence on microbially mediated mineralization of C, N, and S with the help of enzymes is not well established. This study was designed to investigate the effect of different biomass conversion processes (microwave pyrolysis, carbon optimized gasification, and fast pyrolysis using electricity) on the composition and surface chemistry of biochar materials produced from corn stover (Zea mays L.), switchgrass (Panicum virgatum L.), and Ponderosa pine wood residue (Pinus ponderosa Lawson and C. Lawson) and determine the effect of biochars on mineralization of C, N, and S and associated soil enzymatic activities including esterase (fluorescein diacetate hydrolase, FDA), dehydrogenase (DHA), ß-glucosidase (GLU), protease (PROT), and aryl sulfatase (ARSUL) in two different soils collected from footslope(Brookings) and crest (Maddock) positions of a landscape. In this study, the surface chemistry of biochar materials varied with the biomass feedstock type and pyrolytic process. Chemical properties including pH, C/N, C/S, and O/C ratios of high temperature biochar materials produced from different batches of gasification process were fairly consistent. Biochar materials were found to be highly hydrophobic (low H/C values) with high aromaticity, irrespective of biomass feedstock and pyrolytic process. The short term incubation study showed that biochar had negative effects on microbial activity (FDA and DHA) and some enzymes including ß-glucosidase and protease. This phenomenon caused a reduction in C and N mineralization during the period of incubation. Aryl sulfatase activity was not significantly increased by the incorporation of biochars, which indicated the dominance of inorganic S rather than organic and ester-S forms in both soil and biochar. Overall the responses of mineralization, microbial, and enzymatic activity were dependent on C/N and C/S values of amendments and also varied with soil properties.