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Water Into Wine

Author: Barry Dugan
August, 2010 Issue

Vineyard owners and managers are increasingly turning to high technology to monitor soil moisture and conserve water—without harming grape quality.

We live in an age where water is quickly becoming the most precious natural resource on the planet, and where the technology to conserve this essential liquid is evolving just as rapidly.

When it comes to water, California has a rich tradition of power grabs, political gamesmanship and skullduggery. In the latest chapter of this epic struggle, the state stands at the brink of long-term water shortages that will make the worst droughts seem commonplace. Climate change, population growth and endangered species have conspired to create a legitimate water crisis.

This has all upped the ante for new technologies that make the most of every drop. One of those is a wireless environmental sensing system for agriculture that’s being used by grape growers to monitor irrigation as a means of not only conserving water, but also producing the premium fruit that winemakers demand.

More and better information

One of the proving grounds for this technology is a four-acre hillside vineyard on the slopes of Mt. Veeder, where retired high-tech engineer Mark Holler tends his vines. After 25 years with Intel developing a variety of computer chips and systems, Holler transferred his analytical and problem-solving skills to the field of viticulture.

His Mt. Veeder property, which he bought in 2000, is a “highly variable vineyard, like most hillside vineyards,” with 10 distinct areas, each with its own soil characteristics, sun exposure and climate. He was originally using a weather station that let him use just two soil moisture sensors, but it wasn’t giving him enough information.

“So I started looking around for some other technology,” says Holler. He found a company called Crossbow, which had some raw technology, and he went to work refining it and developing what’s now the Crossbow eKo Pro Series, an outdoor wireless system that can accommodate as many moisture sensors as a grower needs. More than a weather station, the system provides real-time data that lets a vineyard manager see precise soil moisture readings every 15 minutes—and check them via the Internet. It lets growers know when to irrigate, the effectiveness of an irrigation event, and provides the ability to closely control vine stress, a key to producing great wine grapes.

Holler’s sensors are also installed to measure water source pressures, tank and reservoir levels and pressure drop across his irrigation head’s filter. He still lives part-time in the South Bay and can monitor his vineyard conditions from his home computer or cell phone. “I’d know before my vineyard guy if the filter was plugged from 80 miles away,” he says, adding that the technology has unlimited application. “It’s just the beginning.”

Soil moisture monitoring is nothing new to winegrowers. But being able to get real-time data from several soil depths is a new layer of information. Growers measure vine water stress using a “pressure bomb” that uses a pressure chamber to measure leaf water potential and correlate it to soil moisture. Others use neutron soil probes, which use radioactive material to gauge soil moisture. Growers also use visual surveys. “A lot of growers use shoot tips as a stress indicator and check the leaf spacing on the shoots,” says Holler. “A farmer is a right-brained guy…and this data can be used in conjunction with a lot of other information. He might look at the tendrils and the leaf water potential and get a sense of how the two relate.”

No substitute for being there

Grape growers have several incentives to use water-saving technologies but, primarily, it lets them use as little water as possible and place just the right amount of stress on the vines to produce the optimum grapes. Finding that balance is the key.

“The ultimate goal is go make premium wine grapes,” says Kerry Damskey, owner of Palmieri wines and Terroirs Artisan Wines in Geyserville and founder of the international wine consulting firm Terroirs, Inc. “Calculated stress keeps the cell elongation down, which means you have smaller berries. The goal is to have an optimum berry-to-pulp size.”

Damskey says there are still growers who measure soil moisture with pressure bombs and neutron probes and “quite honestly, you can look at a vine and see pretty easily when it’s getting stressed.”

Any technology that allows for a more exact reading of stress certainly has value. “I look at it as a tool,” says Damskey. “Winemakers and grape growers make a better product with tools. They’re important, but there’s no substitute for being out in the vineyard.”

Holler agrees. “The soil moisture data is information to interpolate between those field visits,” he says. “I’m definitely not saying you should substitute it for whatever information you’ve already been using. There’s no reason not to use existing knowledge. It’s simply a new piece of data.”

He looks at the data his sensing system produces, “And I look at the other things—the vines, the weather, the weeds. I use it as another source of information. If you’re putting water in the soil, you really ought to know what’s down there already.”

The wireless monitoring system uses soil moisture sensors placed in the ground at a variety of depths and connected to solar-powered wireless network nodes mounted atop trellis poles. The information is relayed to a base radio connected to a dedicated gateway computer that interfaces with any Internet connection. The advantage of the eKo system is, it comes with its own server, so the owner has no monthly subscription or service fees other than the Internet connection.

In the vineyard, it’s a mesh network that connects the system of nodes that are networked in a daisy-chain, with wireless range of up to two miles line-of-sight per hop. In Holler’s network, there are 25 nodes that extend throughout his vineyard and around to another vineyard next to his, which he manages. “At this point, I don’t know of any limitations,” he says. “I’m sure it would extend 8 to 10 miles” with line-of-sight connections.

In addition to allowing a carefully controlled stressing of the vines, the system also saves considerable amounts of water, which is a significant benefit in water-scarce areas such as Mt. Veeder. In the second year of using the eKo system, Holler was able to harvest nearly four tons to the acre of Cabernet Sauvignon using just 34 gallons per vine from June to harvest. By the end of that rain-scarce year, growers were trucking water to the mountain vineyards in the area.

“If you can grow better grapes and conserve water, it seems like a no-brainer to me,” says Holler. “But it’s a new technology, and people take time to accept new technologies.”

eKo in action

In the upper end of the Napa Valley, Edgar Lantz grows 23 acres of classic Bordeaux grapes: Cabernet Sauvignon, Merlot, Petite Verdot, Cabernet Franc and some Petite Sirah. His market is boutique wineries with high-end Napa winemakers, who can be very demanding. Prior to setting up the eKo Pro monitoring system, the irrigation system for his Calistoga vineyard wasn’t precise enough.

“We were using an irrigation system where my vineyard manager was looking at the plants and saying it’s time to water,” says Lantz. “They were looking at the shoot tips and so forth and doing pressure bombing, but I was concerned. That only tells you certain things. You don’t really know what’s happening down in the soil beneath the plants.”

With multiple soil sensors, Lantz can monitor the soil moisture conditions throughout his vineyard. “This system really showed me how different my soils were and how differently one block retains water from the next,” he says. “We have blocks that we water 75 percent more than others. Before, we were just going out and watering all blocks at the same time just by eyeballing it. Now we’re very selective and can tell when we need to water [with more precision].”

And for his clients, the precise amount of water he applies to the vines is critical. “I’m dealing with these really high-end winemakers who want me to stress the vines within reason,” says Lantz. “They don’t want me to put too much water on the vines. I want to give the plants just enough water to make them—and the winemakers—happy.”

Precision agriculture

The use of technology to monitor soil moisture and tailor irrigation schedules is a practice used in what’s known as precision agriculture. In the case of small-scale viticulture, it entails using technology as an aid to manage the variability within a vineyard. Mark Greenspan, operator of Advanced Viticulture LLC in Windsor, works with growers in managing all aspects of their operations. “I consider water management and irrigation to be part of the bigger picture,” he says. “And those fit into a precision approach to viticulture.

“First of all, you should be planting your vineyard according to your soil,” says Greenspan. “You should do a soil survey before you plant. It really comes down to water- and nutrient-holding capacity. Even then, you’re still going to have some variability, and it’s about managing that variability assisted by this technology.”

As a general adviser to growers, Greenspan says, “I’m trying to get across a philosophy rather than specifics. The bigger message is three main best management practices: Wait as long as possible before irrigating; know your soil and root zone so that irrigation volume can be optimized, Then, create your irrigation schedule and monitor your vineyard to modify your irrigation schedule. In my consulting practice with individual growers, I get into more specifics about how much water—if any—to apply and when.”

Greenspan uses a variety of instruments to monitor plant water status. In addition to the aforementioned pressure bombs, he’s been touting the leaf porometer, either stand-alone or in combination with the pressure chamber. He uses several types of moisture sensors to obtain feedback about the penetration of irrigation water and the dry-down of soil between irrigation events. “If the vine is getting too stressed, you have to change your thinking,” he says. “We use stress without going too far. That’s where the instrumentation comes into play.”

The tendency for growers is to irrigate too soon, says Greenspan. “I try to steer them away from irrigating too soon and then to manage the vine stress,” he says. “I try to show them how deep the root system is. I dig holes in the ground to show them. They see how deep [the roots] are and understand that they probably don’t need to irrigate for a while. Once they do start irrigating, I want them to irrigate only to the bottom of the root system and monitor the soil moisture at several depths.”

Soil moisture sensors, such as the eKo system, can indicate the soil moisture pattern and how deep it goes during each irrigation event. “We use the soil moisture curves during and between irrigation events to help us decide how to adjust the water volume and irrigation intervals.”

Greenspan is conducting a vineyard water conservation demonstration project for the Sonoma County Water Agency. Last year he used a variety of irrigation treatments, applying different amounts of water (and, in one case, no water at all) to a vineyard block at Hoot Owl Creek/Alexander Valley Vineyards. Soil moisture monitoring devices were used and plant status monitoring was conducted weekly.

The results showed that water savings ranged from 60 to 100 percent from standard grower practice, largely by delaying the onset of irrigation for as long as possible. The water savings ranged from $19 to $30 per acre. The reduced irrigation resulted in lower yields, but Greenspan says small increases in irrigation would likely increase productivity.

He also took his preliminary conclusions a step further and extrapolated them over the approximately 60,000 acres of vineyards in the Russian River basin. The estimated water savings (depending on the irrigation treatment) ranged between 12,524 and 16,713 acre feet (an acre foot of water is enough to cover an acre of ground in a foot of water). The cost savings were estimated at $1.1 to $1.8 million and the energy savings ranged from 6.4 to 10.3 million kWh of electricity. That also translates to a reduction of 5,000 to 8,169 tons of CO2 emissions.

Greenspan says the extrapolation exercise, particularly the carbon emissions reduction, was “a little bit abstract for some people, but I think it’s been an interesting topic. To me, it’s a nice secondary offshoot of the idea of conserving. The reality is, even in the water-rich environment we have in Sonoma County, we still have a lot of competition for water. There are many users, not just agriculture. I think the wine industry and growers are doing a great job in using very little water in their vineyards, as compared to most other crops—and certainly compared to municipal water use. Yet, I think they can always do better.”

Next step: sustainability

One of the ways they do better is with the help of Sonoma County Winegrape Commission, whose mission (among other things) is education of grape growers. Nick Frey, the commission’s president, says his members are quick to use technology when it’s available. “Some of these new methods give you instantaneous readings over time, and the technology is becoming more available and more useful. It’s being embraced by growers both large and small,” says Frey. “Growers are trying to figure out when they need to start irrigating and not start it too early.”

He says there’s “a tremendous amount of incentive not to over-irrigate. You can increase your canopy management costs, and it affects your wine quality.” Frey believes a lot of growers are already taking great strides to conserve as much water as they can.

The careful monitoring of soil and irrigation schedules is part of practicing sustainable farming—an overused and under-defined word. “Today, it’s all about growing better grapes and being more sustainable,” says Greenspan. “But let’s try to put some flesh on those meaningless words. It’s all about putting as little on the vineyard as we can. As little nutrients, as little water and as few tractor passes. It’s about doing less and approaching that natural state. It’s about applying fewer inputs to a farm. That lets the vineyard express itself better. They say the ideal expression of terroir is a dry-farmed vineyard. We want to get as close to that as we can.”

Given that criteria, if using a wireless system with a series of probes in the soil helps you cut your water use, it’s sustainable. If it means logging on to your computer and seeing how far down your last irrigation went, it’s sustainable.

Mark Holler says the information he receives from the wireless sensing system cannot be duplicated any other way. “The data is rich, because it lets you see something you can’t see otherwise,” he says. “It’s a good thing to have in your toolbox.”

From his hillside perch, Holler has a view of Mt. Diablo in the distance to the southeast. At night, the lights along the Napa River as it widens on its path toward the Bay twinkle just above the hilltops.

He gestures out toward his vineyard and says his wireless system “is just the Internet going into another layer…it’s going out into the environment. That,” he says, pointing to a node perched on a trellis pole, “is the end of the Internet.”

The wireless system also brings him the weather conditions in his vineyard—humidity, rainfall, and such. He also uses it to monitor temperatures where his wine is aging in barrels.

“Think of the node as a mule,” he says, “that carries information in from the field.”

And requires no feeding.



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