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Please use this identifier to cite or link to this item: http://hdl.handle.net/10204/8933

Title: Estimating water use of mature pecan orchards: A six stage crop growth curve approach
Authors: Ibraimo, NA
Taylor, NJ
Steyn, JM
Gush, MB
Annandale, JG
Keywords: Agricultural water management
Pecan orchards
Crop coefficients
Growing degree days
Fractional canopy cover
Issue Date: Nov-2016
Publisher: Elsevier
Citation: Ibraimo, N.A., Taylor, N.J., Steyn, J.M., Gush, M.B. and Annandale, J.G. 2016. Estimating water use of mature pecan orchards: A six stage crop growth curve approach. Agricultural Water Management, 177, pp 359–368
Series/Report no.: Wokflow;17583
Abstract: Mature pecans use large quantities of water and therefore the accurate estimation of water use or evapotranspiration (ET) of pecan orchards is critical for judicious irrigation water management and planning. Measuring ET under all possible combinations of climate and management practices is not possible, and as a result, models are used to estimate ET. Empirical modelling approaches are more widely adopted than the more complex mechanistic models, as they are more easily parameterized, but they are not always easily transferred across a wide range of growing conditions, making local evaluation and validation essential. This study evaluated existing crop coefficient models in a mature pecan orchard for three seasons in a semi-arid subtropical climate. Whilst the generic FAO-56 approach, using parameters provided for stone fruit performed reasonably well on a seasonal basis, accurate monthly estimates of ET were not achieved throughout the season. A closer analysis of data from the current study and a previous study in New Mexico, revealed that a six stage crop coefficient curve should be considered for pecans, together with higher mid-season crop coefficient (K(subc)) values for mature orchards. More accurate estimates of monthly ET for mature pecan orchards were obtained when reference K(subc) (K(subc-subref) values for a well-managed mature pecan orchard in New Mexico were adjusted for local conditions of climate, using a growing degree day—K(subc) relationship and canopy cover. The adjustment for climate should, however, be used with caution. A comparison between seasons at Cullinan and with New Mexico suggests that whilst thermal time is likely to predict the start of leaf fall, it is unlikely to accurately predict canopy development at the start of the season. As a result it is suggested that in future a crop growth curve based on visual observations of phenological stages is developed.
Description: Copyright: 2016 Elsevier. Due to copyright restrictions, the attached PDF file only contains the abstract of the full text item. For access to the full text item, please consult the publisher's website. The definitive version of the work is published in Agricultural Water Management, 177, 359-368
URI: http://www.sciencedirect.com/science/article/pii/S0378377416303080
ISSN: 0378-3774
Appears in Collections:Water resources and human health
General science, engineering & technology

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