Water Conservation Field Day pulls in the crowd in the Alexander Valley

Vineyard owners look to the experts to learn more about water conservation during drought as well for every day

By the looks of the crowd at a recent Water Conservation Field Day event in California's Alexander Valley, vineyard- and land-owners throughout Sonoma, Mendocino and Napa counties are hot to trot when it comes to conserving water.

As a service to the agricultural community, the Sonoma County Water Agency sponsored the event in conjunction with the Sonoma County Winegrape Commission, the Sonoma County Farm Bureau and the United Winegrowers of Sonoma County.

The workshop, held on two separate days at Hoot Owl Creek and Alexander Valley Vineyards, drew close to 200 participants, among them vineyard owners, irrigation specialists and conservationist groups like the National Marine Fisheries Service.

"I think the workshops were effective and we put out a lot of useful information," said Nick Frey, president of the Sonoma County Winegrape Commission. "With growers, it often takes them seeing an example and discussing it with other growers to make a change. I think we provided that forum." 
 
Gathered under the shady oaks in the beautiful vineyard, workshop participants were welcomed by industry expert Dr. Mark Greenspan of Advanced Viticulture LLC, who then introduced Aruturo Carvajal, a water management engineer with National Resources Conservation Service.

Carvajal's presentation detailed how to measure distribution uniformity and application efficiency throughout a vineyard using various equations and tools. In short, calculating application efficiency is invaluable for determining the amount of water necessary for optimal irrigation duration.

But what exactly is optimal irrigation duration? As the group moved out into the vineyard setting, Greenspan illustrated one way to find out. Using a backhoe to dig a four-foot trench between vineyard rows is, to Greenspan, the best way to investigate a root system. By climbing into the pit it is possible to observe rooting depth and soil moisture of the irrigated zone. Irrigation duration should equal root depth.

According to Frey, this is one of the most important aspects of the workshop that many vineyard owners took away. "We all need to conserve water and this one thing--watering just to the bottom of the root zone and not beyond--is critical to put into practice," said Frey.

After climbing out of the pit, Greenspan showed a series of different irrigation techniques including using two emitters per vine versus one. The conservation group as a whole is a proponent of the two-emitter system as it provides more uniformity at a lower flow rate while exposing the roots to more water, creating a larger root zone.

Comparisons between a longer, less frequent versus a shorter, more frequent irrigation cycle were also highlighted using soil moisture devices to monitor wetting depths and drying cycles between irrigation events. Greenspan believes the shorter, more frequent irrigation practice is more water-use efficient.

Another part of the demonstration focused on low-volume vineyard cooling practices. Generally used only in areas of extreme heat like the Alexander Valley and parts of Cloverdale, traditional vineyard cooling systems (consisting of high-volume overhead sprinklers) use three-times as much water as the demonstration over-vine misters. According to Matt Lamborn of Pacific Geodata, the over-vine misters, nothing more than retrofitted drip emitters, work without clogging, even with pond water in full algae bloom.

"With the over-vine misters, there is more suspension of fog in the air which results in prolonged cooling. We recorded an average cooling of 7 degrees when using this method," said Lamborn. Of course, both Greenspan and Frey pointed out that many vineyard owners prefer to use vineyard orientation and canopy management to shade grape clusters whenever possible.

Also part of the demonstration were various plant-monitoring devices that can provide real time measures of soil and plant water status. Generally installed in a vineyard at stress points and a comparison neutral zone, the devices are invaluable for determining effective and efficient irrigation practices. Data from the monitors installed in the demonstration vineyard can be viewed at www.advancedvit.com.

With the demonstrations completed, the group repaired for a lovely lunch under the oaks complete with Alexander Valley Vineyards wine.

"We had a really good turnout for both of the conservation demonstrations," said Frey. "We hope people will take away what they learned and put it into practice.

After harvest, the group will be doing some educational seminars on conserving water during frost protection. In addition to drought issues, other problems with irrigating for frost stem from the potential to deplete sections of streams that can strand vulnerable and endangered fish populations.

For more information on the conservation field day or best practices presented, please visit www.sonomawinegrape.org.