Assessing Olive Evapotranspiration Partitioning from Soil Water Balance and Radiometric Soil and Canopy Temperatures

Francisco Santos

doi:10.3390/agronomy8040043

Abstract

Evapotranspiration (ETc) partitioning and obtaining of FAO56 dual crop coefficient (Kc) for olive was carried out with the SIMDualKc software application for root zone and topsoil soil water balance based on the dual crop coefficients. A simplified two source-energy balance model (STSEB), based on daily remotely sensed soil and canopy thermal infrared data and retrieval of surface fluxes, also provided information on partitioning ETc for the olive orchard. Both models were calibrated and validated with ground-based, sap flow-derived transpiration rates, and their performance was compared in partitioning ETc for incomplete cover, intensive olive grown in orchards (≤300 trees ha−1). The SIMDualKc proved adequate in partitioning ETc. The STSEB model underestimated ETc mostly by inadequately simulating soil evaporation and its contribution to the total latent heat flux. Such results suggest difficulties in using information from the STSEB algorithm for assessing ETc and dual Kc crop coefficients of intensive olive orchards with incomplete ground cover.

Highlights

A reliable assessment of olive water requirements at different stages in the olive’s development is relevant for the correct estimation of daily water needs and the improvement of irrigation management
Usage of the dual Kc approach is appealing in two counts; it allows for the partitioning of ETc and the estimation of potential, non-stressed transpiration, T, which is more suitable for irrigation management purposes, as it closely relates to crop yield [7,10,11,12], and the estimation of soil evaporation, whose accuracy is improved with the procedure [12,13]
The comparison of transpiration data simulated by SIMDualKc (TSDUal ) with observed data (Tsf ), for the two years is shown in Figure 2, which includes ETo, rainfall, and irrigation data

Summary

Introduction

A reliable assessment of olive water requirements at different stages in the olive’s development is relevant for the correct estimation of daily water needs and the improvement of irrigation management. The usual approach for the estimation of crop water requirements is the crop coefficient Kc -ETo approach adopted by FAO56 [8]. Usage of the dual Kc approach is appealing in two counts; it allows for the partitioning of ETc and the estimation of potential, non-stressed transpiration, T, which is more suitable for irrigation management purposes, as it closely relates to crop yield [7,10,11,12], and the estimation of soil evaporation, whose accuracy is improved with the procedure [12,13].

Objectives

Methods

Results

Conclusion