Using the dual-Kc approach to model evapotranspiration of Albariño vineyards (Vitis vinifera L. cv. Albariño) with consideration of active ground cover

This research aims at testing the dual crop coefficient approach to model the evapotranspiration of the traditional Galician “semi-trellised” vineyard of Vitis vinifera cv. Albariño with active ground cover. A separate calculation of soil evaporation, transpiration of the vine crop and transpiration of the active ground cover was conducted. Three irrigation treatments – rain-fed, surface and subsurface drip irrigation – were conducted during three crop seasons (2008–2010). The SIMDualKc model, that performs the soil water balance with the dual Kc approach, was applied for estimating crop evapotranspiration (ETc) by calculating a basal crop coefficient for the vine crop (Kcb full), another for the active ground cover (Kcb cover), which represent the transpiration component of ETc, and a soil evaporation coefficient (Ke). The model was calibrated and validated by comparing model simulated with TDR observed soil water content data. A good fit was obtained showing that modeling was accurate when using the observed fraction of active ground cover, its density and its height, and calculating Kcb cover with field measured data, thus allowing to assess the active ground cover transpiration. As for the vine crop, the best fit was obtained for Kcb full ini = 0.30, Kcb full mid = 1.15 and Kcb full end = 0.90.

► Using the SIMDualKc model, a separate calculation of soil evaporation and of the transpiration of the vine crop and of the ground cover crop was performed.
► The model was calibrated and validated using observed soil water content data.
► Basal crop coefficients were obtained for the vine, the ground cover and both vegetation types together.
► The model allows understanding the dynamics of water use by the vine, the ground cover and soil evaporation, as well as the effects of groundcover management practices.