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tillage.til

Purpose

tillage.til defines each named tillage operation. Each record fills one tillage_db entry in the tilldb array. Tillage operations referenced in chem_app.ops and management decision tables look up the implement by name to get the mixing efficiency, mixing depth, random roughness, and ridge geometry that drive soil-mixing and surface-roughness updates in mgt_newtillmix_* and mgt_tillfactor.f90.

The reader also scans for the entry named biomix. If present, its effmix and deptil are copied into the module-level bmix_eff and bmix_depth, which control the daily biological mixing computed in mgt_biomix.f90. If no biomix entry is present, bmix_eff defaults to 0.2 and bmix_depth defaults to 50 mm.

Source

Format

  • Line 1: title (skipped).
  • Line 2: header (skipped).
  • Lines 3+: one record per tillage operation. List-directed read into tilldb(itl) (type tillage_db).
# Field Type Units Default Description
1 tillnm char(16) none "" tillage operation name (key from management schedules). The literal name biomix sets the biological mixing parameters at the module level
2 effmix real none 0.0 mixing efficiency of the tillage operation (fraction of soil mass redistributed within the till depth)
3 deptil real mm 0.0 depth of mixing caused by the tillage operation
4 ranrns real mm 0.0 random roughness imparted to the soil surface
5 ridge_ht real mm 0.0 ridge height
6 ridge_sp real mm 0.0 ridge interval (or row spacing)

Example

First lines of refdata/Osu_1hru/tillage.til (which has the title and header lines the reader expects):

tillage.til: written by SWAT+ editor v2.2.0 on 2023-03-22 04:25 for SWAT+ rev.60.5.4
name                   mix_eff        mix_dp         rough      ridge_ht      ridge_sp  description
puddle                 0.980       150.000        00.000         0.000         0.000    rice_paddy_puddling_oprtn

The trailing description column is not in tillage_db. List-directed reads stop after the six fields are filled, so the description is silently discarded.

The Ames database has many more operations (the first records, after a correct two-line header, are):

chiselplow             0.65          225          20             0             0     chiselplow
cltiweed               0.3           100          15             0             0     cultiweeder
moldboardplow          0.95          250          30             0             0     mldboard
biomix                 0.01           50           0             0             0     biological_mixing

The biomix row above sets bmix_eff = 0.01 and bmix_depth = 50 at the module level after the file is read.

  • chem_app.ops and lum.dtl (and similar decision tables). Tillage operations reference tillnm from this file.
  • codes.bsn. The active carbon model (cswat) selects which mgt_newtillmix_* routine performs the soil pool mixing.
  • hru-data.hru and landuse.lum. Identify the HRUs that receive the tillage operations defined here.