Evaluation of potential irrigation water savings by assessing the soil water balance in a vineyard in central Chile

The main aim of this study was to evaluate the potential savings of irrigation water by assessing the soil water balance during the growing season in a wine vineyard in the Maule region, Chile. This study provides insights into the influences of different irrigation water applications on soil water status and its potential effects on grape yields, water use efficiency (WUE) and the cost of irrigation to help improve irrigation practices in the region and other similar Mediterranean regions. The field experiment compared three levels of irrigation water applied: current irrigation of the vineyard (T-0) and two deficit irrigation treatments with reductions to 75% (T-1) and 50% of the irrigated water (T-2). The measurements included volumetric soil water content, shallow groundwater table, canopy cover and grape yield at harvest during the entire growing season (October 2017 to April 2018). We found a potential reduction of 25% or 50% in the current irrigation system while maintaining the grape yield, increasing the WUE and reducing the cost of irrigation. Consideration of the water stored in the soil by the accumulation of rainfall in the winter season and the potential for capillary rise of shallow groundwaters is crucial for adjusting irrigation to vine water requirements.