Impacts of Sixteen Different Biochars on Soil Greenhouse Gas Production

One potential abatement strategy to increasing atmospheric levels of carbon dioxide (CO 2 ) is to sequester atmospheric CO 2 captured through photosynthesis in biomass and pyrolysed into a more stable form of carbon called biochar. We evaluated the impacts of 16 different biochars from different pyrolysis/gasification processes and feed stock materials (corn stover, peanut hulls, macadamia nut shells, wood chips, and turkey manure plus wood chips) as well as a steam activated coconut shell charcoal on net CO 2 , methane (CH 4 ) and nitrous oxide (N 2 O) production/consumption potentials through a 100 day laboratory incubation with a Minnesota agricultural soil (Waukegan silt loam, total organic carbon = 2.6%); Wisconsin forest nursery soil (Vilas loamy sand, total organic carbon = 1.1%); and a California landfill cover soil (Marina loamy sand plus green waste-sewage sludge, total organic carbon = 3.9%) at field capacity (soil moisture potential = -33 kPa). After correcting for the CO 2 , CH 4 and N 2 O production of the char alone, the addition of biochars (10% w/w) resulted in different responses among the soils. For the agricultural soil, five chars increased, three chars reduced and eight had no significant impact on the observed CO 2 respiration. In the forest nursery soil, three chars stimulated CO 2 respiration, while the remainder of the chars suppressed CO 2 respiration. In the landfill cover soil, only two chars increased observed CO 2 respiration, with the remainder exhibiting lower CO 2 respiration rates. All chars and soil combinations resulted in decreased or unaltered rates of CH 4 oxidation, with no increases observed in CH 4 oxidation or production activity. Biochar additions generally suppressed observed N 2 O production, with the exception being high nitrogen compost-amended biochar, which increased N 2 O production. The general conclusions are: (1) the impact on trace gas production is both dependent on the biochar and soil properties and (2) biochar amendments initially reduce microbial activity in laboratory incubations. These preliminary results show a wide diversity in biochar properties that point to the need for more research. Permanent URL: http://hdl.handle.net/2047/d10019583