Modeling water and salinity risks to viticulture under prolonged sustained deficit and saline water irrigation

A numerical model (HYDRUS-1D) was used to evaluate the impacts of the long-term (2004–2015) use of sustained deficit irrigation (10% (D10%) and 20% (D20%) less than full), irrigations with increased water salinity ( EC iw of 0.5 and 0.8 dS/m), 50% deficit irrigation during a drought period (DD50%), and DD50% coupled with an increased salinity of water ( EC iw of 0.5 and 0.8 dS/m) on the water balance and salinity dynamics under grapevine in two soils at two locations with different climatic conditions. The results showed that D20% and DD50% significantly reduced water uptake and seasonal drainage ( D r ) by the vines as compared to full irrigation. Vineyards established in light-textured soils showed two to five times larger drainage losses as compared to heavy-textured soils. The results revealed that the slight increase in the electrical conductivity of irrigation water ( EC iw = 0.5 and 0.8 dS/m) increased the risks in terms of the amount of salts deposited in the soil and transport of large quantities of irrigation-induced salts beyond the root zone. Hence, it is imperative to monitor all of the important water, soil, and salinity drivers of agro-hydro-geological systems to understand the hydro-salinity dynamics and to ensure the long-term sustainability of irrigated viticulture.