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fertilizer.frt

Purpose

fertilizer.frt lists every fertilizer product the simulation can apply, with its mass fractions of mineral nitrogen, mineral phosphorus, organic nitrogen, organic phosphorus, and the share of mineral N that is in the NH3 form. Each record fills one fertilizer_db entry in the fertdb array. Fertilizer operations (in chem_app.ops and the management decision tables) reference entries here by name.

Source

Format

  • Line 1: title (skipped).
  • Line 2: header (skipped).
  • Lines 3+: one record per fertilizer product. List-directed read into fertdb(it) (type fertilizer_db).
# Field Type Units Default Description
1 fertnm char(16) none "" fertilizer name (key referenced by chem_app.ops and management decision tables)
2 fminn real kg min-N / kg fertilizer 0.0 fraction of fertilizer that is mineral N (NO3 + NH3)
3 fminp real kg min-P / kg fertilizer 0.0 fraction of fertilizer that is mineral P
4 forgn real kg org-N / kg fertilizer 0.0 fraction of fertilizer that is organic N
5 forgp real kg org-P / kg fertilizer 0.0 fraction of fertilizer that is organic P
6 fnh3n real kg NH3-N / kg min-N 0.0 fraction of mineral N content that is NH3

The five real fractions must sum to less than or equal to 1 for a single product. fminn + fminp + forgn + forgp is the total nutrient mass per unit fertilizer; the remainder is carrier mass.

Example

First lines of refdata/Ames_sub1/fertilizer.frt:

fertilizer.frt: written by SWAT+ editor v2.2.2 on 2023-10-17 14:43 for SWAT+ rev.60.5.4
name                     min_n         min_p         org_n         org_p         nh3_n         pathogens  description
elem_n                 1.00000       0.00000       0.00000       0.00000       0.00000              null  ElementalNitrogen
elem_p                 0.00000       1.00000       0.00000       0.00000       0.00000              null  ElementalPhosphorous
anh_nh3                0.82000       0.00000       0.00000       0.00000       1.00000              null  AnhydrousAmmonia
urea                   0.46000       0.00000       0.00000       0.00000       1.00000              null  Urea
46_00_00               0.46000       0.00000       0.00000       0.00000       0.00000              null  46_00_00
18_46_00               0.18000       0.20200       0.00000       0.00000       0.00000              null  18_46_00
dairy_fr               0.00700       0.00500       0.03100       0.00300       0.99000              null  Dairy_FreshManure

Notes on the example:

  • The editor writes two trailing columns (pathogens and description) that are not in fertilizer_db. List-directed reads stop once the type is filled, so both trailing tokens are discarded by the reader. The literal null in the pathogens column has no effect.
  • For urea, fminn = 0.46 and fnh3n = 1.00. That is, 46% of the product is mineral N, and 100% of that mineral N is in the NH3 form.
  • For 18_46_00, fminn = 0.18 and fminp = 0.202. Note that the third value in the "46" position is the P (P2O5 converted to P), not P2O5 directly.
  • chem_app.ops. Fertilizer applications in management schedules reference fertnm from this file.
  • manure_db.frt. The manure-type database (manure_database, in the same module). Lists named manure types and points to their organic-matter, pesticide, pathogen, heavy-metal, salt, and other-constituent profiles. Not the default fertilizer database, but ships in the same folder.
  • manure_om.frt. The manure organic-matter attributes database (manure_attributes, in the same module). Lists the carbon, water, and nutrient fractions used to allocate manure applications into the soil C and N pools. Loaded separately from fertilizer.frt.
  • codes.bsn. The active carbon model (cswat) controls how N from fertilizer enters the soil pools.