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California’s drought has become an integral part of the conversation around Wine Country. Nothing is immune from discussion, from how many toilet flushes are acceptable to the types of gardens and lawns that are best suited in an era with less available water.

As the area’s largest and most valuable crop, North Coast grape growers have been a popular point of focus as well as contention. In fact, an ongoing debate over the centuries-old practice of dry farming highlights the increasing pressure the industry faces as the state grapples with a new water reality that Gov. Jerry Brown said will take “unprecedented actions” to solve.

For some, the practice of dry farming — where natural rainfall, not irrigation, is used exclusively to produce a crop — is rooted in history. Yet, it is relevant to modern times as Napa wines that won the historic 1976 Paris tastings came from grapes that were dry farmed, though some of the chardonnay fruit was irrigated.

Proponents of dry farming note that drip irrigation can overly protect the vine from stress needed to produce top-quality wines, delay the development of full flavors until later in the growing season and result in wines with higher alcohol content.

“A bigger question is why people irrigate?” said John Williams, the owner of Frog’s Leap Winery in Napa, which has been dry farming its eight vineyards since opening 35 years ago.

For others, however, the practice is ideal, but not feasible to be widespread throughout the area’s diverse landscape, especially in areas where the soil is sandy and vineyard roots are not deep, such as hillsides. Not all soil is similar to that of Napa Valley, where Williams estimates about 20 percent of the vineyards dry farm.

“Shallow soil does not hold sufficient moisture to grow a vine,” said Rhonda Smith, the viticulture farm advisor for the UC Cooperative Extension in Sonoma County.

Additionally, research has shown that dry farming can reduce a crop yield significantly, bringing serious economic consequences.

“Dry farming is a question to look at closely,” said Laurence Sterling, operations manager for Iron Horse Ranch and Vineyards in Sebastopol. “It’s a question of where, what and how?”

Sterling argued the root system along Iron Horse’s 160 acres of vineyard around the Green Valley American Viticultural Area (AVA) would be too stressed relying solely on dry farming because of its soil makeup, a fine sandy loam soil called “Goldridge” where the roots don’t go down more than five feet. “Vine roots grow where there is water,” Sterling said. “The vine can’t be physically moved.”

So who’s right? Like many contentious topics, both sides have valid arguments. But growers and academics said they don’t expect a massive exodus to dry farming in the future. However, within the debate, there is a serious recognition that growers are moving toward using the smallest amount of water possible — and not a drop more — especially through new technologies such as soil moisture monitors and devices that gauge the vine’s water status. It may not be “dry farming,” but it’s tilting toward the idea that conserving water is better for quality, the environment and the long-term health of the vine.

“I see an increasing number of growers that are doing components (of water conservation),” Smith noted.

In the past, the topic of dry farming was inside baseball more suited for grower workshops and trade articles. But not anymore as every water usage practice comes under the public microscope in the current drought, which was classified last week as severe to extreme on the North Coast, according to the National Drought Mitigation Center.

And bigger battles are ahead, especially over groundwater regulations. Brown signed legislation last year that may restrict how much water commercial and residential users are allowed to pump from underground aquifers.

Locally, Sonoma County must form a local agency to implement policies to achieve sustainable groundwater levels in each of the area’s 14 underground basins by June 2017.

According to a survey last year by Wine Business Monthly, about 73 percent of Napa vineyards rely on groundwater for their farming, while Sonoma County came in a little less at 64 percent.

A test case on the issue can be seen at Benziger Family Winery in Glen Ellen, which isn’t surprising given it has been at the forefront of environmentally friendly farming. It utilizes biodynamic farming, where crops are grown without chemicals in an attempt to have the farm’s ecosystem be balanced, self-sustaining and healing.

With the fervency of an old-time pastor, Mike Benziger, the winegrower and general manager, talks about the winery’s 10-year journey in search of more eco-friendly farming practices, bringing in a geologist, soil biologists and a climatologist, who warned him to prepare for the drought the state is now experiencing. He also relied on Mark Greenspan, a Windsor consultant with a Ph.D. in agricultural engineering, who brought him some new technology to gather as much data as possible to inform decisions, including a very important one: When to irrigate and how much?

“We devised a weekly irrigation plan,” Benziger said. “We were able to look at it drop by drop.”

The results have been significant, Benziger noted. Ten years ago, the winery used from 90 to 100 gallons of water per vine. Today, on average, it uses about 30 gallons.

In one notable example, Benziger and Greenspan were able to wean from irrigated water some sauvignon blanc, cabernet sauvignon and cabernet franc vines located on the Sonoma Mountain AVA. To begin, they attempted to see how long they could delay the first irrigation in the vineyards noted for their heavy and deep clay. The two would use the soil and plant measurements to confirm the vines had ample moisture and were not overly stressed. They also visited the vineyard on a regular basis to verify the canopy and fruit were in good condition.

After a three-year process, 36 percent of Benziger’s vineyards are now dry farmed on Sonoma Mountain.

“We went from a regularly irrigated vineyard to being able to dry farm much of it last season, even in a dry year,” Greenspan noted.

Greenspan is especially bullish on the amount of water that can be saved, believing if these water-saving strategies are implemented widely, water use for irrigation could be reduced by half. A rule of thumb is that each acre of vineyards requires about 100,000 gallons of water to deliver the equivalent of 4 inches for irrigation. On average, the majority of grape growers use about 2 to 4 inches of water on their vineyards annually, depending on how risk averse they are.

Given the heightened attention, Greenspan has seen his business increase as well. “Some of this is due to drought as wineries are putting more emphasis on irrigation management,” Greenspan said.

But it comes at a cost. Spending on water-prevention measures can easily total tens of thousands of dollars. In addition, research has shown dry irrigation will significantly produce smaller yields of grapes at harvest, according to a study by Larry Williams, a viticulture and enology professor at UC Davis.

Williams surveyed two chardonnay crops in the Carneros region of Napa, The dry-farmed area used 213 gallons of water per vine per season (all coming from the soil). In contrast, the irrigated grapes used 295 gallons per vine.

However, the yields for the dry farmed fruit totaled 4.9 tons per acre, while the irrigated grapes were at 6.3 tons per acre.

“If you are not concerned about yield … it’s not a big thing,” he said.

Grape quantity is a much bigger concern in the Central Valley where most of the state’s wine grapes are grown, but they also are much less valuable and go into the lowest-priced wine. But yield is still a concern, even locally, where Napa’s famed cabernet sauvignon grapes sold for an average of $5,815 per ton last year, according to Ciatti Co., a San Rafael wine and grape broker.

Brad Peterson, vineyard manager at Silver Oak Cellars, which produces cabernet sauvignon wine with grapes from the Alexander Valley, said his winery has invested a lot of technology to better curtail its water use, including a new irrigation system that will automatically check for leaks and irrigate at specific times. But at the mention of dry farming for his crops, Peterson raised a central question that revolves around the local economy where the wine industry contributes an estimated $13 billion in direct and indirect economic impact, according to an industry-funded study.

“It’s possible to do dry farming,” Peterson said. “But not at the production levels we have gotten used to.”

The Sonoma County Winegrowers, a trade group representing local farmers, has made a push for all vineyards to be 100 percent sustainable by 2019. More than half of the vineyard acreage in the county has undergone a voluntary assessment of sustainability practices. But even within that drive, the issue of dry farming is not universal. Some do make a practice to note their dry farming, such as Emeritus Vineyards, which is near Iron Horse in Green Valley, contending it “helps the grapes achieve full ripeness without excessive sugars and extracted flavors.” Some old vine zinfandel in the Dry Creek Valley has been dry farmed for generations.

“Is it sustainable to dry farm?” Peterson asks. “In some cases the property can be dry farmed. … But if you can’t make a profit farming, it’s not sustainable.”

Williams of Frog’s Leap said he sees resistance to dry farming similar to when organic grape farming came on the scene around 25 years ago. He noted that he’s received around 26 inches of rain this growing season, twice as much as what he claims he needs.

Even with all his efforts, Benziger conceded that dry faming is not practicable in most Sonoma County vineyards. But with the drought, he envisions that some steps will be necessary in the future. Growers may be required to more precisely track their water needs and usage, put meters on every well, and for some, report how much water they consume.

The industry should be proactive, he noted, turning to the concern he has for this year’s growing season after three large grape harvests. Area vineyards experienced an extremely mild winter this season with few days below freezing and 11 days over 80 degrees, he said, not leaving the vines with any dormancy.

“Climate change is really pressing us,” Benziger said.

You can reach Staff Writer Bill Swindell at 521-5223 or bill.swindell@pressdemocrat.com. On Twitter @BillSwindell.

EDITOR’S NOTE: An earlier version incorrectly described the grapes that were used in Napa wines that won the historic 1976 Paris tastings. Some of the grapes used in the wines were farmed with irrigation.

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