Getting Started

The CENTURY model simulates the long-term dynamics of carbon (C), nitrogen (N), phosphorus (P), and sulfur (S) for different plant-soil systems. CENTURY can simulate the dynamics of grassland systems, agricultural crop systems , forest systems, and savanna systems. The grassland/crop and forest systems, have different plant production submodels which are linked to a common soil organic matter submodel. The savanna model uses the grassland/crop and forest subsystems and allows for the two subsystems to interact through shading effects and nitrogen competition. The soil organic matter submodel simulates the flow of C, N, P, and S through plant litter and the different inorganic and organic pools in the soil.

The model runs with a monthly time step. The major input variables for the model include:

  1. monthly average maximum and minimum air temperature,
  2. monthly precipitation,
  3. lignin content of plant material,
  4. plant N, P, and S content,
  5. soil texture,
  6. atmospheric and soil N inputs, and
  7. initial soil C, N, P, and S amounts.

The input variables are available for most natural and agricultural ecosystems and can generally be estimated from existing literature. Most of the parameters that control the flow of C in the system are in the fix.100 file. Several site parameter sets are included in the Century distribution files; see the List of Standard Sites and Management Schemes for more information.

The user can choose to run the model considering only C and N dynamics ( NELEM =1) or C, N, and P ( NELEM =2) or C, N, P, and S ( NELEM =3).

Version 5 of the CENTURY model consists of monthly and daily time-step versions, which we call Century5 and DayCent5, respectively. Both share a large portion of their algorithms. DayCent5 includes maintanence respiration, daily soil hydrology and soil temperature submodels, and trace gas submodels, and requires for input daily weather data and a few additional site parameters.

How to Prepare and Run a Simulation

There are five main steps you follow in order to prepare a Century simulation:

  1. Create a folder or directory in which to store all simulation files.
  2. Create a site parameter set to define the site's physical characteristics and initial organic matter values.
  3. Create a management scheme which defines planting, harvesting, burning, and other events affecting the site during the simulation years.
  4. If necessary, modify the default model parameter sets.
  5. Specify an output file name.

Other steps you may need to perform include:

  1. Creating a weather data file.
  2. Creating a 14C data file.

After completing these steps, run the simulation, and if the simulation runs to completion, examine the results. If the simulation fails, use the error message description or the troubleshooting hints to fix the source of the problem, and rerun the simulation.

See Also

Overview of the Century Model
The Century Model Interface
Changes Since Version 4