CENTURY Soil Organic Matter Model Version 5

The CENTURY version 5 agroecosystem model is the latest version of the soil organic model developed by Parton et al. (1987). This model simulates the long-term dynamics of carbon (C), nitrogen (N), phosphorus (P), and sulfur (S) for different plant-soil systems through an annual cycle over time scales of centuries and millennia. CENTURY can simulate the dynamics of grassland systems, agricultural crop systems, forest systems, and savanna systems. CENTURY was especially developed to deal with a wide range of cropping system rotations and tillage practices for system analysis of the effects of management and global change on productivity and sustainability of agroecosystems.

Version 4 of the model integrated the effects of climate and soil driving variables and agricultural management to simulate carbon, nitrogen, and water dynamics in the soil-plant system. Simulation of complex agricultural management systems including crop rotations, tillage practices, fertilization, irrigation, grazing, and harvest methods is now possible.

Version 5 includes a layered soil physical structure, and new erosion and deposition submodels. The model code has been rewritten in C++, reorganized, and modified to use platform-independent configuration and output files. Added to this version is graphical-user interface providing ease of configuration and running CENTURY simulations, the Century Model Interface.

CENTURY is composed of a soil organic matter/ decomposition submodel, a water budget model, a grassland/crop submodel, a forest production submodel, and management and events scheduling functions. It computes the flow of carbon, nitrogen, phosphorus, and sulfur through the model's compartments. The minimum configuration of elements is C and N for all the model compartments. The organic matter structure for C, N, P and S are identical; the inorganic components are computed for the specific inorganic compound. The timestep is monthly and the model requires the following driving variables as input:

Monthly average max and min air temperature
Monthly precipitation
Soil texture
Plant nitrogen, phosphorus, and sulfur content
Lignin content of plant material
Atmospheric and soil nitrogen inputs
Initial soil carbon, nitrogen (phosphorus and sulfur optional)

These variables are available for most natural and agricultural ecosystems.