Grape Growers Leverage Technology to Manage Vineyard Water Use

Part One in a Series
Kelseyville, CA – In this third consecutive year of drought, water supply and demand once again have become important issues across California. As of early October, more than 80 percent of California is experiencing “extreme” or “exceptional” drought conditions according to the U.S. Drought Monitor, a collaborative effort of the National Drought Mitigation Center at the University of Nebraska-Lincoln, United States Department of Agriculture, and National Oceanic and Atmospheric Administration.

The main sources of the state’s water supply include surface water (i.e., water in creeks, rivers, lakes, etc.) and groundwater from aquifers beneath the surface of the earth – both of which are sources for municipal water companies, residences, commercial and industrial users, farming, livestock, and other agricultural operations, as well as the environment.

In response to existing drought conditions, several water agencies throughout the state have curtailed some surface water uses and even taken unprecedented steps to begin possible regulation of California groundwaters.

According to the Lake County Water Resources Department, groundwater level fluctuations are part of the normal annual cycle. Typically, Big Valley groundwater levels rise and fall about 15 to 17 feet between spring and fall. In June of this year, Big Valley wells near Adobe and Kelsey Creeks were about 5 feet to 8 feet below the long-term average. Groundwater levels have been monitored in most of Lake County since 1960, with some basins monitored since 1948.

Lake County’s agricultural mix includes approximately 8,718 acres of vineyards, 3,533 acres of walnut orchards, 2,105 acres of pear orchards, 2,254 acres of miscellaneous crops such as wild rice, oat/grass hay, alfalfa, hops, grains, nursery production, vegetables, olives, etc., approximately 700 acres of irrigated pasture for livestock, as well as 90,000 acres of rangeland.

Bruce Bardessono (left), Coastal Viticultural Consultants, and Bruce Merrilees, vineyard manager for Bella Vista Farming, use a neutron probe to take soil moisture measurements at Rooster Vineyard in Kelseyville

Bruce Bardessono (left), Coastal Viticultural Consultants, and Bruce Merrilees, vineyard manager for Bella Vista Farming, use a neutron probe to take soil moisture measurements at Rooster Vineyard in Kelseyville. Merrilees will use the soil data along with vine and weather information to determine precise irrigation water amounts for this block of grapes.

“Lake County grape growers and growers throughout the state have known for decades that water is a precious resource and it must be used judiciously,” said Bryan Rahn, owner of Coastal Viticultural Consultants, one of several firms that provide water management services to grape growers in Lake County and the North Coast. “A large part of my consulting practice is water conservation and improving wine grape quality.”

While a handful of vineyards near Kelseyville and Upper Lake use surface water drawn from Clear Lake, the majority of vineyards use groundwater for irrigation.

Rahn said, “Most growers are keenly aware that without a sound water strategy and sustainable water supply for their vineyards, it is unlikely that those vineyards would survive financially or even physically.”

In fact, nearly all Lake County vineyards use drip irrigation systems to deliver a precise amount of water to the vines at the right time during the vine’s growth cycle. Perhaps a third of these vineyards also use overhead sprinkler systems, mostly to prevent frost damage during the spring.

Lake County grape growers employ a range of cutting-edge technologies and irrigation management strategies for precision irrigation. This technology ranges from high-tech, real-time web-based data to visual observations and shoot-length measurements. For example, growers utilize weather data, crop evapotranspiration (ETc) measurements, real-time soil moisture, vine water status measurements, and hands-on techniques to conserve water.

Bryan Rahn, Coastal Viticultural Consultants, uses an infrared thermometer to measure the temperature of the grapevine leaves, one of several measurements used to determine irrigation requirements.

Bryan Rahn, Coastal Viticultural Consultants, uses an infrared thermometer to measure the temperature of the grapevine leaves, one of several measurements used to determine irrigation requirements.

These technologies, combined with boots in the field, deliver the data that allow growers to precisely and effectively manage their limited water supplies.

While today’s technologies are impressive, these practices are not new to Lake County growers whose vineyard managers have been at the forefront of water management and stewardship for more than three decades. “We began converting our old furrow and sprinkler irrigation systems and installing drip irrigation back in the late 1970s after that drought,” recalled long-time grape grower Walt Lyon. “Drip is a great tool. It saves us water and energy – more crop per drop.”

“Growers don’t want to pump water if it’s not needed,” said Rahn, a Certified Professional Soil Scientist, agronomist, and vineyard consultant for more than 25 years. “Labor and energy are expensive.”

Rahn makes weekly vineyard visits with growers including Bruce Merrilees, vineyard manager for Bella Vista Farming. During these visits, they examine grapevine water status, discuss irrigation water requirements, and use several state-of-the-art technologies to measure the water status of the soil and the grapevines.

“The pressure chamber and infrared thermometer tell us when to irrigate,” Merrilees explained. “The neutron probe measures soil water volume and precisely how much irrigation water we should apply without over-irrigating and wasting water. This year, the pressure chamber data showed us that we could delay irrigating for a couple of weeks in some blocks.”

While many of the tools are high-tech, Rahn uses a low-tech method as well. “Even feeling the grape leaves with your hands is another useful diagnostic tool,” he said. “When leaves are actively transpiring (have sufficient moisture), they are cool to the touch. Not only are the leaves cooler, but so is the fruit. Cooler clusters yield superior fruit quality.”

These soil and grapevine measurements are just part of the efforts Lake County grape growers employ to make the best use of Lake County’s limited water supplies and produce the best possible quality winegrapes.

More of these technologies will be explored in Part Two of this series.

For more information about vineyard technology and water use, contact Paul Zellman, Education Director for the Lake County Winegrape Commission, at (707) 279-2633.

The Lake County Winegrape Commission is a marketing order established in 1991 to promote the region’s premium winegrapes and to assist winegrape growers through marketing, research, and educational programs. For information about the Lake County Winegrape Commission and its programs, call (707) 279-2633, or visit www.lakecountywinegrape.org.

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    Grower Conversation Series: Winegrape Wednesdays 4:00 pm
    Grower Conversation Series: Winegrape Wednesdays @ The Mercantile
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    Grower Conversation Series: Winegrape Wednesdays @ The Mercantile
    You are invited to attend the Grower Conversation series hosted by Lake County Winegrowers. This series aims to connect growers, buyers, and industry experts to discuss the climate of today’s market. Each conversation will feature[...]
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