Biochar enhances nitrous oxide reduction in acidic but not in near-neutral pH soil

Abstract

We quantified nitrous oxide (N2 O) fluxes and total denitrification (N2 O + N2) in an acidic (Ferralsol) and a near-neutral pH soil (Cambisol) to determine whether biochar’s alkalinization effect could be the mechanism inducing potential reductions in N2 O fluxes. In Ferralsol, decreases in N2 O emissions and in the N2 O to N2 O + N2 ratio were observed in both biochar and lime treatments. In Cambisol, neither biochar nor lime decreased N2 O emissions, despite significantly increasing soil pH. The abundance and community structure of nosZ gene-bearing microorganisms indicated that gene abundances did not explain biochar effects, but a higher diversity of nosZ gene-bearing microorganisms correlated to lower total denitrification. Overall, our results suggest that biochar’s potential to decrease N2 O emissions, through soil alkalinization, may be more effective in acidic soils.