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ARS Home » Plains Area » Fort Collins, Colorado » Center for Agricultural Resources Research » Water Management and Systems Research » Research » Publications at this Location » Publication #312976
Title: A new DSSAT-CSM evapotranspiration module: ASCE standardized reference evapotranspiration with dual crop coefficient

Author
item DeJonge, Kendall
item Thorp, Kelly

Submitted to: ASABE Annual International Meeting
Publication Type: Proceedings
Publication Acceptance Date: 1/26/2015
Publication Date: N/A
Citation: N/A

Interpretive Summary: A new ET module was added to the DSSAT-CSM crop model code to calculate potential ET, which combines the ASCE Standardized Reference ET (both grass and alfalfa reference) with the dual crop coefficient described by FAO-56. This new standardized method has three advantages: 1) reference ET is calculated according to recently standardized procedures, 2) basal crop coefficient procedure adequately gives a dynamic vegetative transpiration demand as the season changes, and 3) potential surface evaporation due to early season irrigation and rainfall events is calculated appropriately.

Technical Abstract: Although the DSSAT-CSM series of crop models have been used for decades, new focus has been put on improving evapotranspiration (ET) simulation in crop models. A new ET module was added to the model code to calculate potential ET, which combines the ASCE Standardized Reference ET (both grass and alfalfa reference) with the dual crop coefficient described by FAO-56. This new standardized method has three advantages: 1) reference ET is calculated according to recently standardized procedures, 2) basal crop coefficient procedure adequately gives a dynamic vegetative transpiration demand as the season changes, and 3) potential surface evaporation due to early season irrigation and rainfall events is calculated appropriately. Model results using previous ET modules are compared with the new module, including corn in semi-arid Colorado and cotton in arid Arizona, among others.