Various agricultural soil management practices contribute to greenhouse gas emissions. The
use of synthetic and organic fertilizers adds nitrogen to soils, thereby increasing natural emissions of
N2O. Other agricultural soil management practices such as irrigation, tillage, or the fallowing of land
can also affect trace gas fluxes to and from the soil since soils are both a source and a sink for carbon
dioxide (CO2) and carbon monoxide (CO), a sink for methane (CH4), and a source of N2O. However,
there is much uncertainty about the direction and magnitude of the effects of these other practices, so
only the emissions from fertilizer use are included in the method presented here.