The subject of irrigation in viticulture can be a controversial one. Many Old World wine regions consider rainfall the only natural source of water that will retain the terroir characteristics of the vineyard. In other regions, application of irrigation can influence both quality and yield. In Europe, the rules around irrigation of vineyards can be very strict – though with the changing climate, these regulations are being revisited.
Locally, there are no restrictions or regulations on irrigating vineyards, but it is still a practice that must be carefully considered, monitored and applied as water is one of the main factors that determines quality attributes, such as berry size and intensity of flavour. Too much water leads to very large berries, and a dilution of flavour within the berry – this is why hot, dry vintages are often correlated with excellent wines, as the vines will typically produce smaller berries with highly concentrated flavour.
For younger vineyards, it is important to optimise irrigation so the root system is stimulated to develop and grow deeper into the ground to seek out moisture. At Oldenburg, we carefully manage irrigation and only apply it as needed – and in a highly controlled manner. Our older vineyards very rarely receive irrigation. Their roots are well established and dig deep into the earth to find the moisture they need. If they do require a small amount of drip irrigation, it is usually applied directly after the grapes are harvested, to facilitate the recovery of vines by reducing the stress and help them build up their reserves for winter.
To help us determine which vineyards may need irrigation, Christo uses a device called a pressure bomb. This allows him to determine the approximate water potential of the plant tissue (this means it measures the moisture in the plant itself). All other techniques can only measure the moisture in the soil, and does not indicate whether the plant has taken up that moisture.
Once the moisture levels in the vines are determined, the measurements are compared to set standards and parameters, that are unique and fine-tuned for Oldenburg’s vineyards. Only then does Christo decide whether to irrigate. This approach to a delicate practice like irrigation really shows our precision viticulture in action.