Crop and growth stage specific coefficients (Kc) from the Basic Irrigation Scheduling
(BIS) Excel workbook (Snyder et. al., 2014).
The dataset is an export of the BISm.xlsx workbook's `CropRef` worksheet, with columns renamed
and columns added that map to LandIQ CADWR land use dataset
(landiq_crop_mapping_codes; California Department of Water Resources, 2023).
This dataset provides the information needed to reconstruct a stage-based daily Kc curve when
combined with grass-reference evapotranspiration (ETo), such as that provided
by CIMIS (California Department of Water Resources, 2025).
Format
A data frame with one row per crop and the following columns:
- crop_number
Numeric crop identifier used internally by BIS.
- crop_name
Crop name as listed in the `CropRef` worksheet.
- percent_season_B
Percent-of-season location of growth date B.
- percent_season_C
Percent-of-season location of growth date C.
- percent_season_D
Percent-of-season location of growth date D.
- KcB
Crop coefficient at growth date B (approximately Kc1 for field crops).
- KcC
Crop coefficient at growth date C (mid-season plateau, Kc2).
- KcD
Crop coefficient at growth date D (typically equal to KcC for most crops).
- KcE
Crop coefficient at growth date E (late-season value, Kc3).
- planting_month
Representative planting month used by BIS.
- planting_day
Representative planting day used by BIS.
- harvest_month
Representative harvest month used by BIS.
- harvest_day
Representative harvest day used by BIS.
- landiq_class
LandIQ class code matched by BISm crop number.
- landiq_subclass
LandIQ subclass code matched by BISm crop number.
- landiq_subclass_name
LandIQ subclass name matched by BISm crop number.
Source
Snyder, R., Orang, M., Bali, K., Eching, S., Zaccaria, D. (2014). BISm Basic Irrigation Scheduling Excel program (metric units).
Details
BIS follows the crop-coefficient framework of Doorenbos and Pruitt (1977), in which maximum crop evapotranspiration is calculated as $$ETc = Kc \times ETo.$$
Rather than specifying fixed durations for growth stages, BIS expresses the locations of key growth dates (B, C, and D) as percentages of the total season length between planting (A) and harvest or dormancy (E). Daily Kc values are obtained by linear interpolation between the stage-specific coefficients stored in this dataset.
Growth-stage interpretation depends on crop type:
Field and row crops (Type 1): A-B corresponds to initial growth from planting to roughly 10% ground cover; B-C represents rapid canopy development with Kc increasing toward its mid-season value; C-D is the mid-season period at near-maximum Kc (typically around 75% ground cover); and D-E represents late-season senescence, during which Kc may decline.
Deciduous tree and vine crops (Type 3): there is no explicit initial A-B period; the season begins at leaf-out (B). Kc increases during B-C as the canopy develops, reaches a maximum at approximately 61-63% ground cover during C-D, and declines during D-E toward leaf drop or the first hard freeze.
References
Doorenbos, J., Pruitt, W.O. (1977). Guidelines for predicting crop water requirements. FAO Irrigation and Drainage Paper 24.
Snyder, R.L., Shackel, K.A., Sanden, B., Fulton, A.E., Suvočarev, K. (2024). Irrigation scheduling. In Microirrigation for Crop Production. Elsevier.
California Department of Water Resources (2025). California Irrigation Management Information System (CIMIS).
Examples
data(bism_kc_by_crop)
head(bism_kc_by_crop)
#> # A tibble: 6 × 16
#> crop_number crop_name landiq_class landiq_subclass landiq_subclass_name
#> <dbl> <chr> <chr> <dbl> <chr>
#> 1 1.01 Alfalfa (cycle) P 1 Alfalfa & alfalfa mi…
#> 2 1.02 Artichokes T 1 Artichokes
#> 3 1.03 Asparagus T 2 Asparagus
#> 4 1.04 Barley G 1 Barley
#> 5 1.05 Beans (pinto) F 10 Beans (dry)
#> 6 1.06 Beans (dry) F 10 Beans (dry)
#> # ℹ 11 more variables: percent_season_B <dbl>, percent_season_C <dbl>,
#> # percent_season_D <dbl>, KcB <dbl>, KcC <dbl>, KcD <dbl>, KcE <dbl>,
#> # planting_month <dbl>, planting_day <dbl>, harvest_month <dbl>,
#> # harvest_day <dbl>