> For the complete documentation index, see [llms.txt](https://swatplus.gitbook.io/io-docs/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://swatplus.gitbook.io/io-docs/introduction-1/carbon.md).

# Carbon

Input files for setting up the carbon model using SWAT+

The following input files are the minimum requirements to set up the carbon model using SWAT+

<table><thead><tr><th width="354.132080078125">Input Files</th><th valign="middle">Description</th></tr></thead><tbody><tr><td>Basin (<a href="/io-docs/introduction-1/basin-1/codes.bsn.md">codes.bsn</a>, <a href="/io-docs/introduction-1/basin-1/parameters.bsn.md">parameters.bsn</a>)</td><td valign="middle">Files include control codes for basin-level processes simulation and basin-level parameters, respectively</td></tr><tr><td>Carbon Coefficients (<a href="/io-docs/introduction-1/carbon/carb_coefs.cbn.md">carb_coefs.cbn</a>)</td><td valign="middle">Coefficients needed to simulate the carbon fluxes (optional; if not present, default values will be used)</td></tr><tr><td>Climate (<a href="/io-docs/introduction-1/climate/weather-sta.cli.md">weather-sta.cli</a>, <a href="/io-docs/introduction-1/climate/weather-wgn.cli.md">weather-wgn.cli</a>,  <a href="/io-docs/introduction-1/climate/pcp.cli-and-precipitation-data-files.md">pcp.cli</a>, <a href="/io-docs/introduction-1/climate/tmp.cli-and-temperature-data-files.md">tmp.cli</a>, <a href="/io-docs/introduction-1/climate/slr.cli-and-solar-radiation-data-files.md">slr.cli</a>, <a href="/io-docs/introduction-1/climate/hmd.cli-and-humidity-data-files.md">hmd.cli</a>, <a href="/io-docs/introduction-1/climate/wnd.cli-and-wind-speed-data-files.md">wnd.cli</a>, <a href="/io-docs/introduction-1/climate/atmo.cli.md">atmo.cli</a>)</td><td valign="middle">Files list the weather stations and weather data for model input</td></tr><tr><td><p></p><p>Databases (<a href="/io-docs/introduction-1/databases/plants.plt.md">plants.plt</a>, <a href="/io-docs/introduction-1/databases/urban.urb.md">urban.urb</a>, <a href="/io-docs/introduction-1/databases/tillage.til.md">tillage.til</a>, <a href="/io-docs/introduction-1/databases/fertilizer.frt.md">fertilizer.frt</a>, <a href="/io-docs/introduction-1/databases/pesticide.pes.md">pesticide.pes</a>, <a href="/io-docs/introduction-1/databases/septic.sep.md">septic.sep</a>)</p></td><td valign="middle">SWAT+ database for plants, landuse, tillage, fertilizer and manure, pesticides, and septic systems, respectively</td></tr><tr><td>HRU (<a href="/io-docs/introduction-1/hydrologic-response-units/hru-data.hru.md">hru-data.hru</a>,  <a href="https://swatplus.gitbook.io/io-docs/introduction-1/hydrology/topography.hyd">topography.hyd</a>, <a href="https://swatplus.gitbook.io/io-docs/introduction-1/hydrology/hydrology.hyd">hydrology.hyd</a>, <a href="https://swatplus.gitbook.io/io-docs/introduction-1/hydrology/field.fld">field.fld</a>, <a href="https://swatplus.gitbook.io/io-docs/introduction-1/hydrology/snow.sno">snow.sno</a>)</td><td valign="middle">Files contain the site-specific topographical and hydrological properties of HRUs</td></tr><tr><td><p>Landuse and Management (<a href="/io-docs/introduction-1/landuse-and-management/landuse.lum.md">landuse.lum</a>,</p><p>​<a href="https://app.gitbook.com/o/-LDlzeF6OrC5B16IXbV8/s/-MTFpIHUB1K63DLhLJaf/introduction-1/landuse-and-management/plant.ini">plant.ini</a>, <a href="https://app.gitbook.com/o/-LDlzeF6OrC5B16IXbV8/s/-MTFpIHUB1K63DLhLJaf/introduction-1/landuse-and-management/management.sch">management.sch</a>,<a href="/io-docs/introduction-1/landuse-and-management/cntable.lum.md">cntable.lum</a>, <a href="https://swatplus.gitbook.io/io-docs/introduction-1/landuse-and-management/cons_practice.lum">cons_prac.lum</a>, <a href="https://swatplus.gitbook.io/io-docs/introduction-1/landuse-and-management/ovn_table.lum">ovn_table.lum</a>)</p></td><td valign="middle">Files contain landuse information, management operations, and schedules necessary for crop growth</td></tr><tr><td><a href="https://app.gitbook.com/o/-LDlzeF6OrC5B16IXbV8/s/-MTFpIHUB1K63DLhLJaf/introduction-1/master-file-file.cio">Master File (file.cio)</a></td><td valign="middle">Files list the names of all input files used in a simulation run</td></tr><tr><td>Soils (<a href="/io-docs/introduction-1/soils/soils.sol.md">soils.sol</a>, soil_lyr_depths.sol, <a href="/io-docs/introduction-1/soils/nutrients.sol.md">nutrients.sol</a>)</td><td valign="middle">Files contain physical soil properties, customized soil layer depth, contents of nutrients and constituents as initialized in the file <a href="/io-docs/introduction-1/initialization/soil_plant.ini.md">soil_plant.ini.</a></td></tr><tr><td>Structural Practices (<a href="/io-docs/introduction-1/structural-practices/tiledrain.str.md">tiledrain.str</a>, <a href="/io-docs/introduction-1/structural-practices/filterstrip.str.md">filterstrip.str</a>, <a href="/io-docs/introduction-1/structural-practices/grassedww.str.md">grassedww.str</a>, <a href="/io-docs/introduction-1/structural-practices/bmpuser.str.md">bmpuser.str</a>, <a href="/io-docs/introduction-1/structural-practices/septic.str.md">septic.str</a>)</td><td valign="middle">Files contain parameters related to structural practices</td></tr><tr><td><p>Simulation  (<a href="https://time.sim">time.sim</a>, <a href="/io-docs/introduction-1/simulation-settings/print.prt.md">print.prt</a>, <a href="/io-docs/introduction-1/simulation-settings/object.prt.md">object.prt</a>)</p><p></p></td><td valign="middle"><p>Files control simulation time, and output files will be printed during the simulation</p><p></p><p>**To view carbon-specific outputs, the following objects should be added to the <em>print.prt file</em> : </p><ul><li><em><strong>hru_cb (Carbon balance HRU outputs)</strong></em> </li><li><a data-footnote-ref href="#user-content-fn-1"><strong>hru_cb_vars  (</strong><em><strong>Carbon balance HRU output variables)</strong></em></a></li></ul></td></tr></tbody></table>

[^1]: **what is this printing actually?**