Impact of Various Biochars On Greenhouse Gas Production Potentials.

A potential abatement strategy to increasing atmospheric levels of carbon dioxide (CO₂) is to sequester atmospheric CO₂ into a more stable form through the use of pyrolysis. Biomass feed stocks are used to generate a more stable carbon form (biochar) that then can be returned to the soil sequestering atmospheric carbon into a slower cycling pool.  We evaluated the impacts of 16 different biochars from different processes and feed stock materials (corn stover, peanut hulls, algae, wood chips, and turkey manure plus wood chips) as well as an activated coconut shell charcoal on net CO₂, methane (CH₄) and nitrous oxide (N₂O) production potentials through 100 day laboratory incubations with three differing soils at a variety of soil moisture contents.  There was CO₂ production from all the biochars, which is highly variable across the various materials and production processes.  This production needs to be accounted for determining the impact of the soil+biochar system.  There was no observable sorption, degradation, oxidation or production of CH₄ or N₂O during the 100 day incubation of solely the biochar with and without water additions.  Following correction for the CO₂ production from the biochar alone, biochar additions in soil generally suppress CO₂ and N₂O production (5-100% reduction in N₂O production).  Biochar amendments universally suppressed CH₄ oxidation capacities (25 to 100% reduction) in laboratory incubations across various soil types.  The impacts on reductions in N₂O production are moisture dependent, with greater reduction being observed at higher moisture contents. However, there is still significant suppression in the production of N₂O at field capacity from biochar additions.