California grape grower Kevin Cantrelle says irrigation management is the foundation of success to every production practice in his wine grape vineyards.
“If you don't irrigate it right nothing else is going to work out for you,” Cantrelle says.
Cantrelle manages 6,000 acres of wine grapes in California's Central Valley and Central Coast for San Francisco-based The Wine Group, the nation's third largest winery and home to labels including Franzia, Corbett Canyon and Glen Ellen.
Every year Cantrelle comes up with a “growing plan” for each vineyard with production and quality goals established according to the winery needs. At the heart of each growing plan is the irrigation program.
“It all starts with water,” he says.
Matthew Fidelibus, University of California Cooperative Extension Viticulture Specialist at the Kearney Research and Extension Center, Parlier, Calif., says irrigation management is a powerful tool for influencing not only yield and fruit quality, but vine maturity, sunburn, pest pressures and nutrient status in the vineyard.
The key, he says, is to match the overall management strategy with the individual goals in the vineyard, which will be different depending on whether vines produce for raisin, table or wine grapes and the fruit quality and other demands of the buyer.
For Cantrelle, production is still the key to profitable farming his San Joaquin Valley wine grape acreage.
“For my company and what we do, production is the driving factor and we want to produce quality grapes as affordably as possible,” he says. “When you're producing a quality wine at a low price point, you have to keep your inputs low. We compete with ‘Two Buck Chuck’ and labels in that arena, so it only allows us to produce our grapes at a certain price per ton before we can no longer maintain that price point.”
Cantrelle says that through real-time monitoring of soil and vine moisture status in his vineyard he has been able to improve yields significantly through more informed irrigation decisions. Also, he is increasing yields without a significant bump in production costs and with less time spent in each vineyard.
Cantrelle credits a new system called Agricultural Resource Management from PureSense Environmental Inc. with giving him the real time, season-long data and analysis he needs to follow soil moisture status, canopy climate conditions and irrigation system operation throughout the season to make more informed and immediate irrigation decisions.
Soil moisture stations with probes are buried from 1 to 5 feet below the surface. They, along with temperature and humidity sensors on the station, send site-specific data every 15 minutes that Cantrelle can access anytime from his office computer. He can also receive alerts about changes needing immediate attention on his cell phone.
This system joins a growing list of automated and manually accessed weather and data gathering systems growers are using to more closely monitor weather and water needs in specific vineyards.
After setting moisture status targets based on data analyzed from current and previous years, Cantrelle will supplement his drip irrigation sets with flood water before the deep profile is depleted and vines are stressed. Pressure on/off switches lets him compare moisture status to when his system has actually run.
“Now we can see after we irrigate when the peak moisture is and what is the draw down to calculate when our next irrigation will be. And the PureSense communication system allows me to integrate several things into the information I get. It's plug and play,” he says.
After experimenting with the system last season, The Wine Group this year installed PureSense stations in all 12 of its vineyards throughout California. Probes are placed within each variety block and across different soil types. Plans next year call for at least a dozen more stations.
“As you get into it more and more you start realizing the necessity of having this type of technology,” Cantrelle says. “Knowing what's going on inside your ground is invaluable. I don't see how you can farm without knowing what's going on in the soil.”
The Wine Group first installed the system on 600 acres of Zinfandel, Syrah and Rubired grapes at Northwood Vineyards in Madera, Calif. As with other sites, Cantrelle says the system has helped significantly boost his production while meeting the winery's sugar and other quality requirements.
While many growers are reporting yields this year off as much as 30 percent from last season's bumper crop, Cantrelle says his production is off only about 10 percent from last year and his Zinfandel block yielded 2 tons more per acre than the vineyard's five-year average.
“I attribute that to the fact that we know 100 percent of the time what's going on with our soil moisture from 2 to 5 feet down,” Cantrelle says.
Cantrelle says he has not only improved yields, but also helped reduce pressures from mites that might infiltrate stressed vines. At Northwood, this is the first year Cantrelle has not sprayed for mites in his eight years managing the vineyard.
Dave Bynum, an independent PCA who works with The Wine Group, says having a healthy canopy particularly beyond harvest helps ward off the effects of insects and diseases and also improve fertility uptake after harvest to improve storage for next season's crop. At the Wine Group's ultra premium vineyards such as Concannon in Livermore, Bynum says PureSense also helps manage deficit irrigations more accurately to impart well-timed stress without sacrificing vine health.
“The system confirms that we can build our deep soil moisture and keep it within a frame that we like to see,” Bynum says. “If the probe shows we are taking moisture out of the deep profile, it allows us to fill the profile before the vines get stressed. As a result, the vine vigor and the canopy of the vine after harvest look better, so we're hoping we will keep picking up nutrients in the fall and then maintain production the following year.”
The soil moisture stations are one tool in a set of irrigation management strategies that include canopy temperature and humidity sensors, evapotranspiration rates and pressure bombs that help The Wine Group fine-tune irrigation management.
Fidelibus says soil moisture measurement is a good complement to evapotranspiration and a vine-based moisture measuring system.
“If you have the interest and the money to measure soil water, it's worth doing. It can help you refine your understanding of your vineyard. It's one more piece of information you can use to help you understand the story of water use in the vineyard,” he says.
Cantrelle says monitoring deep soil moisture helps confirm that what he is doing is right and tells him in advance when he needs to make an adjustment before the soil profile dries down.
“Before, we were running our irrigation off of 110 percent ET or more and found that we still were not getting enough water down at the 3-and 4-foot level. Even though we were watering more than what we thought we were supposed to, we found we really weren't watering enough,” he says.
“Now we are watering at 125 percent ET and even though we had above average temperatures this summer we were able to keep vines healthy and maintain the crop. Hopefully, the lack of stress during bud differentiation will bode well for our crop going into next year, too.”