Nitrogen additions to ecosystems have a range of effects besides increasing carbon storage. For example, nitrogen additions generally increase the loss of nitrous oxide (N2O), a potent greenhouse gas, from soils (figure. 2). While absolute emissions rates are considerably lower than carbon fluxes from terrestrial ecosystems, N2O is roughly 200 times more powerful as a greenhouse gas and fertilization increase N2O emissions into the atmosphere many fold (Schimel et al, 1996). Nitrogen additions also frequently reduce rates of methane (CH4) oxidation in soils, thereby either reducing soil sinks for CH4 or increasing CH4 fluxes from soils (Delgado et al, 1996; Neff et al, 1994). Methane (CH4) and nitrous oxide (N2O) contributes 2.8 Pg eq yr-1. Of global anthropogenic emissions in 2005, agriculture accounts for about 60% of N2O and about 50% of CH4.