Transpiration and Water Use of an Irrigated Traditional Olive Grove with Sap-Flow Observations and the FAO56 Dual Crop Coefficient Approach

Abstract

The SIMDualKc model was applied to evaluate the crop water use and the crop coefficient (Kc) of an irrigated olive grove (Olea europaea L.) located in Sicily, Italy, using experimental data collected from two crop seasons. The model applies the FAO56 dual Kc approach to compute the actual crop evapotranspiration (ETc act) and its components, i.e., the actual tree transpiration (Tc act), obtained through the basal crop coefficient (Kcb), and soil evaporation according to an evaporation coefficient (Ke). Model calibration was performed by minimizing the difference between the predicted Tc act and the observed daily tree transpiration measured with sap flow instrumentation (TSF field) acquired in 2009. The validation was performed using the independent data set of sap flow measurements from 2011. The calibrated Kcb was equal to 0.30 for the initial and non-growing season stages, 0.42 for the mid-season, and 0.37 for the end season. For both seasons, the goodness-of-fit indicators relative to comparing TSF field with the simulated Tc act resulted in root mean square errors (RMSE) lower than 0.27 mm d−1 and a slope of the linear regression close to 1.0 (0.94 ≤ b0 ≤ 1.00). The olive grove water balance simulated with SIMDualKc produced a ratio between soil evaporation (Es) and ETc act that averaged 39%. The ratio between actual (ETc act) and potential crop evapotranspiration (ETc) varied from 84% to about 99% in the mid-season, indicating that the values of ETc act are close to ETc, i.e., the adopted deficit irrigation led to limited water stress. The results confirm the suitability of the SIMDualKc model to apply the FAO56 dual Kc approach to tree crops, thus assessing the water use of olives and supporting the development of appropriate irrigation management tools that are usable by farmers. A different way to estimate Kcb is based on the approach suggested in 2009 by Allen and Pereira (A&P), which involves the measured fraction of ground covered (shaded) by the crop and the height of the trees. Its application to the studied grove produced the mid-season Kcb values ranging from 0.40–0.45 and end-season Kcb values ranging from 0.35–0.40. The comparison between the A&P-computed Tc act A&P and TSF field shows RMSE values ranging from 0.27 to 0.43 mm d−1, which demonstrates the adequacy of the latter approach for parameterizing water balance models and for irrigation scheduling decision making.

Searching for Sustainable-Irrigation Issues of Clementine Orchards in the Syrian Akkar Plain: Effects of Irrigation Method and Canopy Size on Crop Coefficients, Transpiration, and Water Use with SIMDualKc Model

“…The reported goodness-of-fit indicators for the E1 and E2 experiments are within the ranges of values reported in the literature for the SIMDualKc simulations of perennial crops for vineyards [67,[76][77][78], peach orchards [42], and olive groves [66,79,80]. They are also similar to those reported by Darouich et al [52,53] for horticultural crops grown in the same edapho-climatic conditions in the Akkar plain.…”

“…For Experiment 1 (2007Experiment 1 ( -2011, an Fr of 0.55 was adopted for all crop stages, which corresponds to the upper value suggested for medium density and height of citrus trees. For Experiment 2, an Fr value of 0.61 was assumed, corresponding to the central value of The reported goodness-of-fit indicators for the E1 and E2 experiments are within the ranges of values reported in the literature for the SIMDualKc simulations of perennial crops for vineyards [67,[76][77][78], peach orchards [42], and olive groves [66,79,80]. They are also similar to those reported by Darouich et al [52,53] for horticultural crops grown in the same edapho-climatic conditions in the Akkar plain.…”

Water Use and Soil Water Balance of Mediterranean Vineyards under Rainfed and Drip Irrigation Management: Evapotranspiration Partition and Soil Management Modelling for Resource Conservation

“…Issues related to the quality of the measured dataset and the empirical one-dimensional modeling approach used here to describe the soil water balance in a three-dimensional drip irrigation system may also help explaining why the goodness-of-fit indicators are not as high as in former studies, e.g., Paço et al [88]. Nevertheless, the reported goodness-of-fit indicators are within the range of values reported in the literature for soil water content simulations of field crops [89,90], vegetable crops [91,92], and perennial crops [58][59][60][61] using the same model.…”

“…Examples of applications to vine and fruit crop systems can be found in the recent literature review provided by Rallo et al [53] and Pereira et al [56]. The SIMDualKc model [57] has adopted the dual-K c approach for estimating daily ET fluxes of crops grown under different climatic regions and management practices, including grapevine [46,47,58], peach [59], and olive [60,61]. Yet, despite the growing use of the FAO56 dual-K c approach for computing crop evapotranspiration fluxes and improving soil water management in complex agricultural systems, there is still the need for extending research focusing on the search for standard K c and K cb values as well the impact of active ground cover, cover crops, and mulches on crop evapotranspiration of vine systems [53].…”

Estimating crop coefficients and actual evapotranspiration in citrus orchards with sporadic cover weeds based on ground and remote sensing data

“…In other words, the K c values for the mid-season, when soil evaporation and weed transpiration were limited, resulted lower than the segments relative to the late and the non-growing seasons, in which rainfall and evapotranspiration from the soil surface occur. Similar annual patterns of crop coefficient have been recently reported by Puig-Sirera et al ( 2021a ) for an olive orchard and by Segovia-Cardozo et al ( 2021 ) in a citrus orchard in which, focusing on the full year and not only on the growing season, it was observed that K c values in non-growing periods resulted in higher values than in the growing period, due to the large contribution of soil evaporation.…”