Extension of the EPIC model for greenhouse gases

  • Project Title: Extension of the EPIC model for greenhouse gases. Collaborating GEO-BENE partners: BOKU, IIASA


    EPIC is a daily time step model capable of simulating many agro-ecosystem processes including crop growth, tillage, wind and water erosion, runoff, soil density, leaching and soil organic matter dynamics. Recently, the EPIC model was extensively modified with algorithms describing C and N transformations in soil following concepts and equations used in the Century model (Izaurralde et al., 2006). The incorporation of greenhouse gases effects is the current and near future into EPIC modeling. The microbial denitrification is modeled on an hourly basis following the concept that oxidation of C releases electrons thereby driving a demand for electron acceptors such as O2 and oxides of nitrogen (NO3-, NO2-, and N2O). Diffusion of O2 or CO2 and N2O respectively, to and from microbial sites is described using a spherical diffusion model. A cylindrical diffusion model is used to describe O2 transport to root surfaces and CO2 and N2O from the root surfaces. Oxygen uptake by microbes and roots is described with Michaelis-Menten kinetic equations. If not enough O2 is present to accept all electrons generated, then the deficit for electron acceptors may be met by oxides of nitrogen if they are available. The movement of O2, CO2 and N2O through the soil profile is modeled using the gas transport equation solved on an hourly time step.


    EPIC source code.


    Simulations in Fortran. Development of process algorithm for greenhouse gases diffusions.


    An refinement and integration of all greenhouse gases into the EPIC model is necessary to investigate the impact of climate policy on the agricultural economics. CO2 is already implemented and validated, N2O is implemented but not yet validated, CH4 is planned to be implemented for the next year


    in progress.