Greenhouse Gas Emissions From Production of Miscanthus Giganteus On Mollisols.

The mitigating effects of substituting bioenergy crops for fossil fuels can be greatly reduced if their production also emit greenhouse gases, such as nitrous oxide and carbon dioxide. N₂O is a greenhouse gas that is 320 times as powerful as CO₂ and many agricultural practices have increased its abundance in the atmosphere. Measurements of greenhouse gas emissions with different levels of fertilization on Miscanthus giganteus (a productive and promising biofuel) is lacking. Therefore, N₂O and CO₂ emissions were measured during a two year study in east-central Illinois Mollisols on Miscanthus giganteus plots with urea fertilizer treatments of 0, 60, and 120 kg N ha^-1. We measured seasonal and temporal emissions of N₂O and CO₂ using a chamber-based flux method. The highest N₂O emission from the Miscanthus giganteus occurred after fertilization in the 120 kg ha^-1 in the early summer in conjunction with a rainfall event (87 µg N₂O-N/m² hr). The 60 and 120 kg ha^-1 fertilization treatments showed similar small N₂O fluxes, which were significantly different from the control plots at the 0.05% significance level. Even though the precipitation during the first year of the study was abnormally high, N₂O and CO₂ fluxes were low compared to literature values from corn and soybean production. These results suggest that the N₂O and CO₂ emissions from Mollisols cropped with Miscanthus giganteus may have low soil greenhouse gas emissions, even with fertilization.