The Impact of Biochar Application and Fertilizer Treatments on N2O Emissions in a Northeastern U.S. Corn Silage Field

Global nitrous oxide (N2O) emissions are mainly produced by agricultural soilsdue to heavy nitrogen (N) fertilizer use. N2O is an extremely potent greenhouse gas (GHG) and ozone depleting substance that requires effective management practices to mitigate its contribution to climate change. Recently, the use of biochar as a soil amendment has emerged as a potential strategy to reduce greenhouse gas emissions in agriculture. However, there is limited knowledge of the underlying mechanisms that drive N2O emissions when combined with biochar. The purpose of this two-year study is to investigate the effect of biochar application combined with fertilizer treatments on N2O emissions. We established two field trials with the same eight treatments: manure broadcast, manure injection, urea fertilizer, and control, all repeated with and without biochar. Following fertilization application in the summer, we collected greenhouse gas emissions (N2O, CO2, CH4) and soil samples (0-15 cm) to determine inorganic N concentrations. Our results showed that fertilizer treatments had a significant impact on N2O emissions, but biochar application did not. Using a boosted regression tree (BRT) model, we found that underlying variables (carbon availability, soil moisture, and nitrate and ammonium concentrations) drove these results, rather than the fertilizer application itself. This research contributes to a broader understanding of how soil N2O emissions are affected by biochar and fertilizer application, and how environmental conditions can drive these emissions. It also highlights the need for further studies to inform the development of feasible management practices for farmers to reduce GHG emissions.