Impacts of Sixteen Different Biochars on Soil Greenhouse Gas Production

Abstract

One potential abatement strategy to increasing atmos-pheric levels of carbon dioxide (CO2) is to sequester atmospheric CO2 captured through photosynthesis in biomass and pyrolysed into a more stable form of car-bon 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 CO2, methane (CH4) and nitrous oxide (N2O) production/consump-tion potentials through a 100 day laboratory incuba-tion 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 CO2, CH4 and N2O 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 CO2 respiration. In the forest nursery soil, three chars stimulated CO2