Fitting measured evapotranspiration data to the FA056 dual crop coefficient method

Richard G. Allen, Ayse Kilic, Andy Suyker, Jane Okalebo

Research output: Chapter in Book/Report/Conference proceedingConference contribution

2 Scopus citations

Abstract

The FAO-56 publication of the UN Food and Agriculture Organization contains guidelines on constructing and applying a 'dual crop coefficient' method to characterize the behavior of evapotranspiration (ET) on a day to day basis. The dual crop coefficient (Kc) method substantially improves the ability to fit simulated with measured data, as compared to the 'single' Kc method, by partitioning evaporation from soil (Es) from transpiration from vegetation. This permits the separate estimation of Es when there are known wetting events from precipitation and irrigation and assists in explaining behavior of measured data. The application of the dual Kc method is relatively straight forward, especially when applied using the straight-line segment method for the basal Kc curve, Kcb. Illustrations are given on fitting the dual Kc method and Kcb curve to daily ET data for irrigated and rainfed corn crops near Mead, Nebraska measured by eddy covariance and sensitivity to various soil and root zone parameters. Assessment of transferring Kcb curve parameters to other fields and years indicates that soil and root zone parameters are relatively transferrable with little modification, whereas lengths of the four crop growth stages do vary from year to year due to differences in cultivar type and possibly differences in weather.

Original languageEnglish (US)
Title of host publicationJoint ASABE/IA Irrigation Symposium 2015
Subtitle of host publicationEmerging Technologies for Sustainable Irrigation
PublisherAmerican Society of Agricultural and Biological Engineers
Pages434-469
Number of pages36
ISBN (Electronic)9781510815513
StatePublished - 2015
EventJoint ASABE/IA Irrigation Symposium 2015: Emerging Technologies for Sustainable Irrigation - Long Beach, United States
Duration: Nov 10 2015Nov 12 2015

Publication series

NameJoint ASABE/IA Irrigation Symposium 2015: Emerging Technologies for Sustainable Irrigation

Conference

ConferenceJoint ASABE/IA Irrigation Symposium 2015: Emerging Technologies for Sustainable Irrigation
Country/TerritoryUnited States
CityLong Beach
Period11/10/1511/12/15

Keywords

  • Consumptive use
  • Crop coefficient
  • Evaporation
  • Evapotranspiration
  • Irrigation water requirement
  • Reference evapotranspiration

ASJC Scopus subject areas

  • Agronomy and Crop Science
  • Soil Science

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