Assessment of Basal Crop Coefficient Adjustment in Grapevines with Active Ground Cover: A Case Study

Competition for water resources makes it necessary to advance research focused on estimating the water needs of row crops, such as vineyards. Following the FAO-56 methodology and the A&P approach, the soil water balance model was applied to a vineyard with continuous vegetation cover in temperate climate conditions (Galicia, Spain). Basal crop coefficients adjusted to local conditions were obtained for both the vineyard and the active vegetation. After SIMDualKc model adjustment, r2 values greater than 0.86 were obtained, along with goodness-of-fit indicators that demonstrate the model’s ability to predict soil water content (PBIASavg = 1.16; EFavg = 0.89; dIAavg = 0.97). A correction factor is proposed that improves the partitioning of the transpiration component in row crops with active cover. The transpiration demand of the vineyard increased by 35% in four study cases (northern Portugal, northwestern Spain, and Italy). The proposed correction factor is shown to be in line with the actual conditions and complex behaviour of a vineyard with active vegetation cover, which opens the way for improved water requirement prediction in complex management situations such as the one studied here. The proposed methodology is expected to improve the efficiency of irrigation management through more accurate determination of the real water amount required by orchards.