Seasonal basal crop coefficient pattern of young non-bearing olive trees grown in drainage lysimeters in a temperate sub-humid climate

Authors: PUPPO, LUCIA - UNIVERSIDAD DE LA REPÚBLICA; GARCIA, CLAUDIO - INSTITUTO NACIONAL DE INVESTIGACION ARGROPECUARIA, URUGARY; Bautista, Eduardo; Hunsaker, Douglas - Doug; BERETTA, ANDRES - UNIVERSIDAD DE LA REPÚBLICA; GIRONA, JOAN - INSTITUTE DE RECERCA I TECNOLOGIA AGROALIMENTARIES (IRTA)

Submitted to: Agricultural Water Management
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/28/2019
Publication Date: 12/20/2019
Citation: Puppo, L., Garcia, C., Bautista, E., Hunsaker, D.J., Beretta, A., Girona, J. 2019. Seasonal basal crop coefficient pattern of young non-bearing olive trees grown in drainage lysimeters in a temperate sub-humid climate. Agricultural Water Management. 226. https://doi.org/10.1016/j.agwat.2019.105732.
DOI: https://doi.org/10.1016/j.agwat.2019.105732

Interpretive Summary: Olive production is widely practiced in the Mediterranean and other semi-arid agricultural regions of the World. As a result, the water requirements of olive trees have been the subject of numerous investigations. However. the cultivation of olive trees for oil production is expanding into humid regions and limited is information is currently available about the water requirements of this crop under these alternate conditions. A study was conducted using containerized trees to characterize evapotranspiration and to separate the soil evaporation component under the humid conditions of Uruguay. These results were then used to determine the coefficients required for the application of the FAO methodology for predicting evapotranspiration, which uses a coefficient to characterize transpiration (basal crop coefficient) separately from evaporation (evaporation coefficient). The plants were drip irrigated throughout the production cycle and were not subjected to water stress. Drainage lysimeters were used to measure total evapotranspiration while micro-lysimeters were used to measure soil evaporation. Crop coefficients for olive trees are difficult to compare because of differences in plant age, variety, density, water management, and crop manage practices across different studies. Nevertheless, results of the study revealed coefficients of similar magnitude as those reported in previous studies and a similar pattern of seasonal variation. These results should be of interest to producers interested in water management of perennial trees and, more generally, to researchers of evapotranspiration processes.

Technical Abstract: Young non-bearing olive trees were grown in drainage lysimeters and their water consumption was measured over two consecutive yearly-experimental periods to analyze the effect of seasonal variations on the basal crop coefficient (Kcb). Micro-lysimeter measurements were used to quantify soil evaporation (Es) and Es was subtracted from evapotranspiration (ETc) to determine transpiration. Monthly mean (Kcb) were determined as (ETc-Es)/ETo, where ETo is the FAO-PM grass-reference evapotranspiration, calculated from locally measured weather data. The observed Kcb value at mid-season, 0.38, was obtained in the fall months, with 41% of canopy cover. The mid-season Kcb when adjusted to the FAO-56 standard climate was 0.43. Seasonal patterns of Kcb are presented and the Kcb value during the mid-season growth-stage was found to be similar to those described in the literature for Mediterranean climates. Variation of the basal crop coefficient was satisfactorily explained by measured canopy light interception (FIR) and a linear regression model is presented for Kcb as a function of FIR.