Understanding the effects of nitrogen (N) fertilization on Miscanthus x giganteus greenhouse gas emissions, nitrate leaching, and biomass production is an important consideration when using this grass as a biomass feedstock. The objective of this study was to determine the effect of three N fertilization rates (0, 60, and 120 kg N ha(-1) using urea as the N source) on nitrous oxide (N2O) and carbon dioxide (CO2) emissions, nitrogen leaching, and the biomass yields and N content of M. x giganteus planted in July 2008, and evaluated from 2009 through early 2011 in Urbana, Illinois, USA. While there was no biomass yield response to N fertilization rates in 2009 and 2010, the amount of N in the harvested biomass in 2010 was significantly greater at the 60 and 120 kg N ha(-1) N rates. There was no significant CO2 emission response to N rates in 2009 or 2010. Similarly, N fertilization did not increase cumulative N2O emissions in 2009, but cumulative N2O emissions did increase in 2010 with N fertilization. During 2009, nitrate (NO (3) (-) ) leaching at the 50-cm soil depth was not related to fertilization rate, but there was a significant increase in NO (3) (-) leaching between the 0 and 120 kg N ha(-1) treatments in 2010 (8.9 and 28.9 kg NO3-N ha(-1) year(-1), respectively). Overall, N fertilization of M. x giganteus led to N2O releases, increased fluxes of inorganic N (primarily NO (3) (-) ) through the soil profile; and increased harvested N without a significant increase in biomass production.
