Water is vital to life, but vineyards can thrive with surprisingly little of it. Water plays a crucial role in grape cultivation, influencing vine growth, grape development, and ultimately, the taste of the wine.
In many regions where vineyards are dry farmed, the amount of moisture received in a year can significantly impact the character of the vintage and how terroir is expressed. However, in areas where dry farming isn’t feasible, vineyards are irrigated, meaning water is controlled by humans rather than nature. This raises questions about how irrigation affects terroir expression, as human intervention alters a fundamental element of grape growing. How do terroir-focused growers in arid regions minimize their impact? What are the effects of irrigation on vines, roots, and the resulting wines?
Irrigation in vineyards isn’t a new practice. Wine historian and archaeochemist Dr. Patrick McGovern notes that “once the grapevine was domesticated, irrigation systems were probably devised.” Evidence of this dates back to the 4th Millennium BC in the dry Jordan Valley, where domesticated grape seeds and wood were found. These vineyards likely depended on irrigation. Similar practices were adopted in the Egyptian Nile Delta around 3000 BC, where early forms of drip irrigation were depicted in tomb reliefs. As grapevines spread to other regions like lowland Mesopotamia and Shiraz, irrigation continued to play a critical role.
How does water access—whether natural or artificial—affect the taste of wine? The impact is multifaceted. For instance, during the ripening phase, more water can slow the vine’s response to warm temperatures, affecting ripening, sugar accumulation, acid levels, and aromas. Conversely, drier conditions can accelerate these processes, leading to noticeable differences in the wine’s character and chemistry. In extreme drought conditions, reduced canopy growth can hinder sugar accumulation, while water stress might enhance fruit character. The amount and timing of water access also influence tannin profiles, berry size, and yield. With irrigation, many of these factors can be managed, such as by applying water during heat spikes. These examples illustrate the far-reaching effects of water on vines and wines.
Still, water is just one aspect of terroir, which also includes temperature, soil type, aspect, slope, latitude, and wind patterns. Although water availability indirectly influences these factors, it’s all interconnected and complex.
“There are two types of irrigation,” says Dominique Roujou de Boubée, owner of Terroir en Botella, who consults for organic vineyards across Spain. “One to increase yield…and the other as a tool to manage a terroir-driven wine in warmer, drier climates—to avoid the shutdown of photosynthesis.”
For vineyards focused on yield, Roujou de Boubée explains that industrial vineyards precisely meet the vines’ needs with water, nutrients, and other inputs to achieve ripeness with higher yields. However, this approach often results in wines with little terroir influence, producing large quantities of impersonal, inexpensive, fruity wines. Essentially, this is akin to hydroponic grape growing.
In contrast, vineyards concerned with terroir can still express it with careful, precise irrigation. The challenge lies in accurately measuring and monitoring water use, which requires expertise or specialized tools.
Growers can adopt creative methods to reduce irrigation and more closely mimic dry farming, providing only the extra water that nature doesn’t supply. Ron Mansfield, owner of Goldbud Farms in Placerville, California, manages several vineyards in the El Dorado AVA, where deep, volcanic clay soils only require irrigation in certain vintages. Clay retains water and nutrients better than other soil types, making minimal irrigation possible. In years with mild weather, Mansfield can sometimes avoid irrigation altogether, but he monitors vine performance closely and adjusts as needed.
Tablas Creek in Paso Robles employs a different irrigation strategy. Depending on winter rainfall, they may irrigate until flowering, but once fruit sets, they cut off water until stress signs appear. This approach allows the vines to mature grapes without excessive water, which could alter their character.
Tablas Creek offers a unique case study, as they farm both irrigated and dry-farmed vines on the same estate, allowing for direct comparison. Surprisingly, during hot periods, the dry-farmed vines often fare better than the irrigated ones. Jason Haas, partner and general manager at Tablas Creek, speculates that this is due to the deeper roots of dry-farmed vines, which access cooler soil layers. The irrigated vines, planted at higher densities, may compete more for water, leading to greater vulnerability.
These differences extend to the wines themselves. Neil Collins, winemaker at Tablas Creek, notes that contrary to his expectations, the dry-farmed wines are not bigger and more powerful but rather more complex and refined. In contrast, the irrigated wines are more robust and tannic.
One critical observation is that irrigation can significantly influence root growth within the soil. Jordan Lonborg, Tablas’ viticulturist, explains that dry-farmed roots tend to spread out and grow deep into the soil profile, while irrigated roots often stay closer to the surface. This difference can lead to variations in how the vines interact with the soil and ultimately affect the wine’s flavor.
It’s important to note that irrigated vines don’t necessarily lead to less authentic expressions of terroir. At Tablas Creek, both irrigated and dry-farmed wines still reflect the estate’s unique character. However, the differences in how the vines grow and the resulting wines’ taste are worth considering. As Collins points out, “Purer terroir expression doesn’t always mean better wine.” This distinction highlights that while dry farming might offer a more unadulterated expression of the land, it doesn’t automatically result in superior wine.
Irrigation, therefore, doesn’t preclude terroir, but it does alter certain aspects of it. Dry farming, too, involves human intervention, from soil preparation to grape variety selection. This complexity reminds us that terroir is an imprecise concept, and human influence is inherent to viticulture. Where irrigation is necessary, thoughtful practices can help growers rely on nature as much as possible, resulting in beautiful wines produced in many different ways.
Water availability and its effects are intricate and offer plenty of material for wine enthusiasts to ponder when considering the essence of wine.
