1.5.5. Running with tillage

Cropland tillage (Sect. 2.21.4) is set to 'low' by default. This can be changed to a value of 'off' (no tillage) or 'high' (high-intensity tillage) for the tillage_mode namelist option.

Depth of tillage can be changed with the max_tillage_depth parameter (meters; default 0.26).

Tillage multipliers for different soil pools and time since planting are defined on the parameter file, in variables bgc_till_decompk_multipliers (for CENTURY soil) and mimics_till_decompk_multipliers (for MIMICS soil). These variables were originally added with the script at tools/contrib/add_tillage_to_paramsfile.py, which can be modified as needed to change tillage multipliers.

1.5.5.1. Example: Crop simulation with no tillage

> cime/scripts/create_newcase -case IHistClm60BgcCrop_notill -res f19_g17_gl4 -compset IHistClm60BgcCrop


> cd IHistClm60BgcCrop_notill
> ./case.setup

# turn off tillage
> echo "tillage_mode = 'off'" >> user_nl_clm

1.5.5.2. Reverting fixes relative to original tillage implementation

The current implementation of tillage in CTSM is based on work by Graham et al. (2021), but with fixes to how days after planting is calculated and to default tillage depth. To run without those changes:

> echo "use_original_tillage_phases = .true." >> user_nl_clm
> echo "max_tillage_depth = 0.32" >> user_nl_clm