Are simple empirical crop coefficient approaches for determining pecan water use readily transferrable across a wide range of conditions?

dc.contributor.authorTaylor, Nicolette Jane
dc.contributor.authorAnnandale, John George
dc.contributor.authorIbraimo, N.A.
dc.contributor.authorSteyn, Joachim Marthinus
dc.contributor.authorGush, M.B.
dc.contributor.emailnicolette.taylor@up.ac.zaen_ZA
dc.date.accessioned2017-07-28T05:46:03Z
dc.date.available2017-07-28T05:46:03Z
dc.date.issued2017-01
dc.description.abstractThe accurate estimation of evapotranspiration (ET) of orchard crops is critical for judicious irrigation water management and planning. However, it is impossible to measure ET under all possible combinations of climate and management practices, which necessitates the use of ET models. Although empirical models are more likely to be adopted by consultants and growers, due to easier parameterization and the requirements for fewer, more easily measured input parameters, they may not always be transferable across a wide range of conditions. As a result these models may not always give acceptably accurate ET values outside of the area in which they were calibrated. This study therefore aimed to evaluate empirical crop coefficient models for pecans in two different orchards which differ in climate and/or fractional canopy cover from where the models were developed. When testing the FAO-56 approach it was found that pecans should not be grouped under stone fruit and that a six stage crop growth should be considered, instead of the traditional four stage curve. Improved accuracy in estimating ET of pecans could, however, be achieved by using a pecan specific reference crop coefficients for a mature orchard and scaling this with fractional canopy cover for different orchards, provided that an adjustment was made for the influence of climate on canopy development. This was achieved by using a published growing degree (GDD) day crop coefficient relationship, provided seasonal accumulated thermal time is below 1600 GDD and that crop coefficients do not exceed 1.1.en_ZA
dc.description.departmentPlant Production and Soil Scienceen_ZA
dc.description.librarianam2017en_ZA
dc.description.sponsorshipThe Water Research Commission (Project K5/1770) with co-funding from the National Department of Agriculture, Forestry and Fisheries of South Africa.en_ZA
dc.description.urihttp://www.actahort.orgen_ZA
dc.identifier.citationTaylor, NJ, Annandale, JG, Ibraimo, NA, Steyn, JM & Gush, MB 2017, 'Are simple empirical crop coefficient approaches for determining pecan water use readily transferrable across a wide range of conditions?', Acta Horticulturae, vol. 1150, pp. 9-14.en_ZA
dc.identifier.issn0567-7572
dc.identifier.other10.17660/ActaHortic.2017.1150.2
dc.identifier.urihttp://hdl.handle.net/2263/61477
dc.language.isoenen_ZA
dc.publisherInternational Society for Horticultural Scienceen_ZA
dc.rightsInternational Society for Horticultural Science. This article is distributed under the Creative Commons Attribution 3.0 License.en_ZA
dc.subjectTranspirationen_ZA
dc.subjectSoil evaporationen_ZA
dc.subjectFractional canopy coveren_ZA
dc.subjectGrowing degree daysen_ZA
dc.subjectEvapotranspiration (ET)en_ZA
dc.subjectGrowing degree (GDD)en_ZA
dc.titleAre simple empirical crop coefficient approaches for determining pecan water use readily transferrable across a wide range of conditions?en_ZA
dc.typeArticleen_ZA

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