It’s common knowledge that managed deficit irrigation on a vineyard improves the quality of the fruit. But in California, a region perpetually water-stressed, that European logic doesn’t always hold. On a typical 80-acre management block, Dr. Sahap Kaan Kurtural and his U.C. Davis research team have found that even if one area of a vineyard performs well under existing irrigation strategy, there is nearly always a second, underperforming zone that can bring down the quality of the entire crop—and the wine made from it.
But Kurtural’s research, which builds on decades-old knowledge from corn and soybean production and mirrors current studies in almond, pistachio, and citrus orchards, has also shown that it’s possible—and increasingly economical—to identify and manage these underperforming zones to improve the quality and consistency of wine grapes.
The earliest iterations of Kurtural’s research relied on methods impractical to most wine grape growers, such as taking pressure bomb measurements of individual plants across large acreages.
His most recently published work took it a step further, showing that instead of measuring individual plants, he could use a soil sensor—mounted on a sled and pulled across the vineyard—to map out zones with particular soil qualities strongly correlated with plant water status. These maps are useful because the two to three zones they typically identify are fairly static, and don’t vary much year to year—but they don’t provide real-time data for irrigation management within each zone.
If growers knew in the moment that the lower-quality zone in their vineyard was underperforming, they could irrigate to alleviate water stress. Some table grape growers are already using on-the-ground sensors to manage these irrigation sub-zones, but their methods are not economically feasible for most wine grape operations. Instead, Kurtural says, “the cheapest and simplest way to do this in real time or near-real time is by sensing above the vineyard”—with aerial data.
Over the next few years, Kurtural is using data from Ceres Imaging to do just that.
For growers who want a view of water stress over the entirety of an orchard, Ceres Imaging provides a proven alternative to pressure chamber testing.
Kurtural plans to use five or six Ceres Imaging flights over the growing season to capture data. He’ll combine this with groundtruthing reports and on-the-ground surface-renewal analyses, which measure heat and water vapor in the vineyard to show evapotranspiration. Using artificial intelligence to interpret and manipulate the information, he hopes to develop an algorithm to guide more precise irrigation management strategies for vineyards. The model he plans to develop could help growers use aerial data from flights over their own vineyards to schedule weeks’ worth of irrigation at a time.
“Fundamental research usually results in a paper,” Kurtural says, but in this instance, “we’re taking it out into the field.” In just a year or two, he hopes, new insights should be ready for growers to use.