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ARS Home » Plains Area » Temple, Texas » Grassland Soil and Water Research Laboratory » Research » Publications at this Location » Publication #423697
Research Project: Enhancing Cropping System and Grassland Sustainability in the Texas Gulf Coast Region by Managing Systems for Productivity and Resilience

Location: Grassland Soil and Water Research Laboratory

Title: Version 1.4.0 - pyfao56: FAO-56 evapotranspiration in Python

Author
item Thorp, Kelly
item GULATI, DINESH - University Of Idaho
item KUKAL, MEETPAL - University Of Idaho
item Ames, Reagan
item Pokoski, Tyler
item DeJonge, Kendall

Submitted to: SoftwareX
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/21/2025
Publication Date: 3/6/2025
Citation: Thorp, K.R., Gulati, D., Kukal, M., Ames, R.B., Pokoski, T.C., DeJonge, K.C. 2025. Version 1.4.0 - pyfao56: FAO-56 evapotranspiration in Python. SoftwareX. 30:102109. https://doi.org/10.1016/j.softx.2025.102109.
DOI: https://doi.org/10.1016/j.softx.2025.102109

Interpretive Summary: The seminal publication of FAO-56 described standardized methods to estimate crop water use or evapotranspiration (ET), which is a critical aspect of irrigation management, water rights in many Western states, and large-scale studies of hydrology. In the first release of the "pyfao56" software, the FAO-56 methodology was programmed using the modern open-source Python programming environment. The current pyfao56 release (version 1.4.0) adds considerable functionality to the original software and previous releases, including updates to evapotranspiration terminology and crop coefficient approaches. The pyfao56 software serves as a useful tool or framework for users of ET-based irrigation scheduling, which includes agronomists, crop consultants, irrigators, and agricultural water researchers.

Technical Abstract: The pyfao56 software package is a Python-based implementation of the standardized evapotranspiration (ET) methodologies described in Irrigation and Drainage paper No. 56 of the Food and Agriculture Organization of the United Nations, commonly known as FAO-56. This update improved pyfao56 by 1) updating ET variables and terminology, 2) adding ET calculations using the FAO-56 single crop coefficient approach, 3) including data on crop coefficients, growth stage lengths, and rooting depths as published in FAO-56 tables, and 4) incorporating optional crop coefficient adjustments for mid-season and late-season weather conditions when mean values for minimum relative humidity and wind speed deviate from 45% and 2 m s-1, respectively. Other minor edits included the addition of the Kling-Gupta efficiency as a goodness-of-fit statistic, error handling when the inputted soil profile depth is shallower than the maximum rooting depth, and improved management of the model version number in the source code.