Impacts of Biochar on Nitrogen Cycling Microbial Communities and Nitrous Oxide Emissions.

Biochar addition can have substantial effects on soil microbial communities, particularly nitrogen (N) cycling processes. Although biochar has the potential to mitigate nutrient losses and nitrous oxide (N­₂O) emissions, results are not always consistent and considerable uncertainty remains about the microbial mechanisms. This study evaluated the hypothesis that biochar-induced changes in microbial community abundance and function leads to a reduction in N₂O emissions in a heavily fertilized maize field. Four treatments were evaluated: control, control + biochar (100 Mg ha^-1), N fertilizer addition (269 kg N ha^-1), and N fertilizer addition + biochar. Gas and soil samples were collected throughout the growing season to determine N₂O fluxes and soil inorganic N concentrations. Soil samples were assayed for potential nitrification and denitrification rates, and the DNA copy number of several N-cycling genes were quantified using qPCR. Preliminary results indicate that biochar application increases potential nitrification rates while decreasing potential denitrification rates. Results from one growing season will be summarized in this presentation.