“Liquor is worth fightin’ for, but water is worth dyin’ for.” Such is an old adage Ken Wright, owner and winemaker of Ken Wright Cellars in Carlton, Oregon, remembers from when he first came to the West Coast in the 1970s. “Water was already an issue,” he says. “When the population of an area cannot be supported by the natural annual rainfall, things get serious very quickly.”
As the climate continues to change, drought conditions throughout the U.S. West Coast continue to get worse and, as a result, growers look for ways to decrease their water use—with some switching off the irrigation hose altogether and turning to dry farming.
What Is Dry Farming?
“Dry farming means that we do not use irrigation and rely on the residual moisture in the soil received during the wet season to supply the vines with water,” explains Dan Warnshuis, proprietor of Utopia Vineyard in Newburg, Oregon. This means that any kind of stored water—even pond water or captured roof-structure water—cannot be used to water crops, whether by hand or through an irrigation system. “Dry farming is particularly important in areas that have a paucity of aquifers.”
To be clear, it’s very uncommon for any vineyard planted to young vines (three years or less) to be dry farmed. “If you did, the plants would die,” notes Wright. “[But] in almost all cases, two years of root development both in spread and depth (average is a foot of depth annually) will allow a grower to then farm without any ‘applied’ water.”
The Role of Soil (and Soil Series)
Whether or not soil is an important component in determining if a vineyard is suitable for dry-farming is almost impossible to evaluate “without knowing the full picture,” says Wright. “The reality is that soil is only the upper horizon of what we are farming. Of equal—and eventually greater—importance is the parent material or ‘mother rock,’ which is completely different than soil,” he emphasizes.
That “upper horizon” of topsoil is where what is referred to as “water holding capacity” is determined by that topsoil’s specific structure. Large-particle soil (like sand) is loose in structure, thus has limited water-holding capacity; small-grain soil (like clay) is densely packed and thus there’s very little space between particles for water to run through—it has a high water-holding capacity.
But, once vines establish their roots, they’re reaching past this top layer. “Vines at maturity (in our area of the Willamette) are 25 to 30 feet deep with soil being as much as 10 feet of that to as little as two feet,” explains Wright.
Only once vines are “engaging” with the parent material do they begin to take in trace elements—magnesium, phosphorous, zinc, iron, potassium—that is then broken down and transported to the plant. “It is only when the root system is past topsoil and engaging [or mining] parent material that we begin to see incredible detail in our wine.”
David Lattin, winemaker of Emeritus Vineyards in Sebastopol, California, illustrates this concept by describing his vineyard’s unique soil series, which he says is ideal for dry farming. “The Goldridge soil at Emeritus has a very permeable sandy layer sitting on top of absorbent clay loam,” he describes. “Rain during the winter and spring percolates through the top layer and is trapped within the clay of the loamy second layer. As the clay loam dries out during the season, the roots follow the water downward.”
As roots penetrate deeper and deeper into the soil series, they’re able to take up more of those trace minerals. “The trace minerals are what make a specific site unique,” adds Lattin. “These minerals have direct and indirect effects on the basic chemistry of the fruit and increase the likelihood of making a more complex wine.”
Effects on the Vine and Wine
Compared to dry-farmed vines, vines dependent on drip irrigation have a high concentration of roots in the less complex topsoil.
“Dry-farmed vines have roots that are more broadly distributed, allowing the vine roots to seek out the nutrients they need using the full area of the vineyard,” explains Ames Morrison, founding partner of Medlock Ames in Healdsburg, California.
By creating a root system that is forced to dig deep for water, the vines become less dependent on a regular water source and thus are less impacted by day-to-day temperature fluctuations and suffer less during extreme heat. Further, less water limits excessive shoot growth, meaning the vine focuses its energy on ripening, rather than producing green material. “Which is important for wine quality,” notes Morrison, adding that less water for green material also results in slightly tougher leaf tissue, making the leaves less prone to insect and disease damage.
Having healthy vineyards that can focus their growing energy on fruit ripening means that dry-farmed vines tend to ripen earlier in the season and at lower Brix, resulting in wines with naturally high acidity and lower total alcohol.
Dry-Farming Is Not for All Soils or Sites
“Dry farming, while common and even mandated in much of the Old World, can be hard, if not impossible, to achieve in climates like California’s,” says Emeritus Vineyards President Mari Jones. Further, the subsoil, the parent material, must be able to hold enough moisture for the vines to grow in the summer when there is no rainfall.
And even if a specific soil series may seem idyllic on paper, a vineyard’s suitability to dry farming is impacted by a whole host of other environmental factors that affect soil absorption and rate of drainage—among them, slope, aspect, temperature and winds.
“Evaluating suitability based solely on the composition of the [soil series] profile, be it volcanic, calcareous or marine sediment is impossible without knowing all of the environmental factors in play,” says Wright. “Any of those compositions could produce world-class or dismally inferior wine depending on the sum of the environmental influences.”
Of course, creating a quality product is always front and center for vintners, and while limiting water intake may strengthen the vine and increase the complexity of resulting wines, as Lattin points out, dehydration events during the growing season can actually do more harm than good to the fruit. “Flavors are created, and real sugar accumulates when leaves are hydrated and healthy,” he says. Therefore, where dry farming is not possible, irrigation is in fact needed to produce healthy grapes and quality wine.
When irrigation is employed conscientiously, in a way that mimics a normal rainfall pattern and does not provide a constant, oversupply of water, the effects can be just as successful as dry farming.
“People often state that they believe irrigation promotes surface rooting that develops at the expense of a deeper root system. This is not my experience,” comments Wright. “We have had the opportunity to see vine profiles that reveal root depth of irrigated vineyards that have proven in every case to be as deep as dry farmed.”
So, in the end, do dry-farmed vines make better wines? Each grower and vintner has his or her own opinion on the topic. But, in the end, as Wright so succinctly puts it: “It’s situational.”
Published: February 10, 2023