2.1. Simulated scenarios
CropSyst, a comprehensive, process-oriented, multi-year and
multi-crop simulation model, was used to evaluate emissions from
the simulated scenarios in the techno-sphere (see Table 1). Further
details on the model, scenarios, and resulting SOC storage changes
and N2O emissions as a function of tillage intensity are given in
Stöckle et al. (2012). Prior to running the reduced tillage scenarios,
SOC was brought into equilibrium by long-term simulations using
CT management. The enhancement of SOC oxidation due to tillage
is an uncertain process that is poorly documented in the literature,
thus its effects are estimated by bracketing a lower and higher
boundary of SOC oxidation enhancement. The simulation scenarios
were run for the lower oxidation boundary and then repeated for
the upper oxidation boundary. SOC values were estimated in the
top 30 cm of soil.
For the different scenarios, CropSyst provided estimations of
yields, residue production and fate, SOC storage changes, and
N2O emission resulting from both nitrification and denitrification.
The model does not consider methane fluxes. It was assumed that
there was no significant difference for methane emissions between
CT and NT (Jacinthe and Lal, 2005; Mosier et al., 2006; Omonode