Water and the neutron probe: when enough is just enough - includes related article on water technology and on wine grapes

With all the new vine plantings going on throughout the U.S. and the recent his tory of irregular weather patterns in California and the Northwest, as well as the growing costs of water, the need to manage water use and increase irrigation efficiency has become critical.

The neutron probe, which was developed about 20 years ago, when used with updated software, is a tool that can be used to generate a vineyard irrigation schedule based on the amount of moisture in the soil available to the vine.

Dana Zaccone, owner of GeoVit Vineyards Services in Napa, says the probe, especially when combined with analysis of vine growth and visual observation of the vines, can assure that vines get the optimum amount of water. Zaccone said the technology has been a great asset in learning the irrigation requirements for the new varieties of rootstock planted to replace AxR over the past several years.

"Since AxR was known to be very hardy and easy to grow, everyone planted it. There was a minimal threat to the vines and the quality of the fruit if you were not applying the proper amount of water. However, observations of vines on root-stocks being planted to replace AxR - 5C, 3309 and 11OR for example - have shown that there is a good chance a vine might not bounce back if it gets too dry. There is also a limited history of bow these rootstocks react to water, which makes the use of accurate data on water needs much more crucial in vineyard management," Zaccone said.

Zaccone is managing a neutron probe system in place at Cakebread Cellars in Napa. Winemaker Bruce Cakebread said, "The computerized data tells us how much moisture is in the soil and helps us determine if plants are beginning to show signs of overwatering or, on the other hand, stress from underwatering. This technology greatly reduces the threat of either over or underwatering, allowing us to use the vineyard systems we have in place to grow the best quality grapes we can while making the best use of scarce water resources. We are able to micro-manage each block with this method." He added, "Our vines are like thirsty men crawling in the desert. It is crucial that they have enough water to stay alive but not enough to stop and open a casino."

Cakebread Cellars maintains 20 sites within its own vineyards and believes so strongly in the systems that it has established 20 more sites with growers. The technology being used by Cakebread consists of a Boart Longyear/CPN hydro-probe combined with software developed by Irricrop Technology of Australia.

Individual probe sites are identified within each specified vineyard to give as accurate a picture as possible of the overall vineyard. Aluminum tubes equaling the length of the root system are then inserted into each site. On a weekly basis, beginning about April 1 and continuing through harvest, the neutron probes are inserted into the tubes at six-inch intervals to count hydrogen atoms. Since water is the only variable hydrogen source in the soil, any changes in the atom count reflect variations in the amount of water present. The data is then transferred via cable from the hydroprobe to a PC equipped with the custom software that reads and plots the data to form the basis of an effective irrigation schedule.

Zaccone said use of the neutron probe is really taking off as water management becomes more critical. "Water management is really the key to the use of the neutron probe. But you also gain a history of grape quality from each block so over time the probe becomes a wine-making tool," Zaccone said.

"Of course, the payoff is the use of water resources, since using too much water is more common than not using enough," he added. "The ideal is to have a site in every distract block where you would want to irrigate separately. It's best to use three tubes in a triangle situation. The standard tube depth is six feet, although you can go 10 feet if you want to monitor the entire zone. Irrigation mainly takes place in the upper five feet of the zone."

The initial costs for installing the neutron probe system are about $10,000 for a 20-probe site, according to Zaccone. Annual costs, including labor to take readings, is about $3,300.

Zaccone estimates the cost of hiring a consultant at about $13,000 annually, so by year two, the cost of owning the probes is less than the cost of hiring consultants. He estimates the five year total at $26,925 or $269 a site.

Following is a breakdown on the average cost per site for five years:

NUMBER       COST OF     CONSULTANT
OF SITES     OWNING        COSTS

5             $741         $650
10             426          65O
15             322          650
20             269          650
30             217          650

"You can see that although developing a neutron probe program appears to be a considerable expense because of the initial cost outlay, the average annual cost over a five-year period is a small price to pay for more effective water management and improved quality. I think over the next several years, as agricultural areas continue to fight over water resources and the use of technology to improve quality becomes more prevalent, you will see a lot more of this being used," Zaccone said.

Kevin Hare and his wife Susan operate Growers Supply and Irrigation in Geyserville, a company that his father started in 1958. Irrigation has changed a lot since then, with the advent of PVC and later polyethylene drip systems being the major breakthrough.

"Now you can go out and push a button and put our whole system into operation. I remember when you had to have the manpower to move aluminum pipes around," he said. "Drip irrigation and vineyards make a particularly good match. It has made irrigation a management tool."

The new systems can fail, Hare said, but in most cases that's due to lack of proper maintenance. "We always tell people that it may be automatic, but you still have to go out and look at it. Flush the system out, check the emitters. Flow-meters are very useful. By the proper use of flowmeters you can tell if you have plugged emitters or line leaks," he said.

Another change he has seen is simply the extra effort of keeping up with the suppliers that provide the working hardware for irrigation systems. "Trade shows are a good way to stay in touch," he added.

Before putting in any sort of irrigation system, it is necessary to have the water on hand, The location of ground water has become increasingly important for agriculture as surface water resources become more scarce. Jeremy Wire, president of Geoconsultants, Inc., said, "Unlike surface water supplies, ground water availability is more predictable and when developed and managed properly, this resource can economically meet the increasing demands of California's expanding communities."

Wire started Geoconsultants in 1976 and says it is one of the few companies in California to use geophysics as the basis Of its work. Wire says that geophysics is a combination of geologic mapping, surface geophysical studies and other research which he believes provides the most cost-effective and accurate approach to ground water exploration.

Rather than drilling test walls, Geoconsultants "simulates" test drilling. Evaluation methods include: regional data research, geologic mapping, air photo interpretation, surface geophysical exploration, lithologic sampling, electrical log analysis, aquifer analysis and computer modeling.

Resources:

Adcon Telemetry, Inc., P.O. Box 7908, Santa Rosa, CA 95407; Tel: (707) 5782330; (800) 352-5309; Fax: (707) 578-2390. Adcon operates weather monitoring stations using a private radio micro-climate network. The stations are useful in pest management, frost warning and irrigation management.

DriWater, 715-P Southpoint Blvd., Petaluma, CA 94954; Tel: (707) 769-5343; Fax: (707) 769-0335. DriWater is a self-contained drip irrigation in gel form which provides water to new plantings for three months or more. It is a subterranean gation so is extremely effective in establishing new plants on hillsides and will reduce weed germination caused by surface moisture. DriWater is 98% water and 2% food-grade ingredients in a gel form, is non-toxic and bio-degradable.

Geoconsultants, Inc., 213 Oakhurst Street, Suite A, Visalia, CA 93291; Tel: (209) 738-1825; Fax: (209) 294-7750. Geoconsultants specializes in the exploration, development and protection of groundwater resources. Services include: ground water resource evaluation and water well location; deep aquifer evaluations; well construction, development and evaluation; aquifer impact evaluations and ground water resource protection

GeoVit Vineyard Services, 551 River Glen Dr., #193, Napa, CA 94558; Tel: & Fax: (707) 257-0382.

Growers Supply & Irrigation, 20750 Gesyerville Avenue, Geyserville, CA 95451; Tel: (707) 857-3484; Fax: (707) 433-6868. Growers was founded in 1958 and has seen its business shift from orchards to grapevines over the years. Growers designs and oversees the installation of irrigation systems throughout the North Coast.

James Hardie Irrigation, 1588 North Marshall, El Cajon, CA 92020. Tel: (619) 562-2950, (800) 333-8125; fax: (800) 892-1822.

T-Systems International, Inc., 7545 Carroll Road, San Diego, CA 92121; Tel: (619) 578-1860 or (800) 765-1860; Fax: (619) 578-2344. T-Systems offers T-TAPE TSX Tree & Vine Model drip tape for surface, suspended or below ground installation. T-TAPE is made of UV resistant polyethylene with a slit outlet which the company says will give years of trouble-free irrigation. It requires 40% less operating pressure than other irrigation systems, the company says.

Wyatt Irrigation Supply, Inc., 747 Yolanda Avenue, Santa Rosa, CA 95404; Tel: (707) 578-3747; Fax: (707) 578-3958; 2200 North State Street, Ukiah, CA 95482; Tel: (707) 462-7473; fax: (707) 462-0746.

TOO MUCH WATER

While most of today's water technology is focused on delivering exactly the right amount of water to grapevines, sometimes Mother Nature plays havoc with those efforts.

January floods in California caused about $11.7 million in damage to the state's vines, according to the California Department of Food and Agriculture. At the time that estimate was made, the flood waters hadn't receded in all parts of the San Joaquin Valley, so the cost could go higher. Much of that damage will be in cleanup costs and repairs to trellis and irrigation systems.

It is estimated that only about 400 acres were completely swept away in flooding, out of the state's total of 354,000 acres. Damage to mature vines should be minimal, as dormant vines are resistant to flooding and can stand in water for up to a month without damage.

Damage was heaviest in the San Joaquin Valley where levee breaks released large volumes of water under great pressure, which can sweep away new planted vines and break mature vines. Damage was light on the North Coast.

WATER AND WINE GRAPES

Using data drawn from Monterey County, an area of relatively low rainfall outside the coastal region, the average water use for wine grapes is 1.57 acre feet annually, according to the Monterey County Water Resources Agency. (An acre foot is the amount of water it would take to cover one acre of land to a depth of one foot.) The average family of four uses about one acre foot of water per year.

Larry Bettiga, the University of California Extension Viticulture Advisor for Monterey, San Benito and Santa Cruz counties, said that the use of cover crops would push water use higher than the average, perhaps to as much as two acre feet annually.

The Water Resources Agency gives the following estimate for agriculture water use in Monterey County in the period from November 1, 1994 through October 31, 1995:

CROP                 ACRE FEET

Truck Crops          367,984
Grapes                71,545
Pasture               23,501
Grain                 14,339
Field Crops           13,957
Sugar Beets           10,027
Orchards               3,127

Total                504,480

This compares to 41,884 acre feet of water pumped for urban use in the county.

The Water Resources Agency also developed numbers on irrigation methods for grapes (and other crops) which doubtless reflects changes taking place elsewhere as well:

DISTRIBUTION OF IRRIGATION METHODS FOR GRAPES, IN ACRES

YEAR     FURROW     SPRINKLERS     DRIP

1993      261        13,347        15,976
1996        0         8,155        21,240

BROCK UNIVERSITY LAUNCHES COOL CLIMATE INSTITUTE

Brock University of St. Catharines, Ontario, Canada has set up a Cool Climate Oenology and Viticulture Institute (CCOVI) as of last December.

The institute was established thanks to funding from the Ontario Grape Growers Marketing Board ($225,000), the Wine Council of Ontario ($250,000) and Don Ziraldo of Inniskinllin Wines ($25,000).

Brock University is seeking a matching $500,000 from the Natural Sciences and Engineering Research Council to establish the university's first-ever industrial Chair.

A South African, Henni Van Vuren, who studies new DNA technology to enhance yeast, will be nominated as the Senior Chair. Andy Reynolds, a Canadian viticulturist, will be nominated as Junior Chair.

Bill Cade, dean, Faculty of Mathematics and Science, said, "this is a landmark event that builds a partnership with the grape and wine industry in Canada and ultimately the world."

Brock University will accept students into a new undergraduate program in enology and viticulture this September.

WINES & VINES & WINETECH

1997 was the last year that Wines & Vines co-sponsored the highly-successful Wine-TECH (now partnered with GrapeTECH).

We are proud to have helped make the trade show a "must event", having started from scratch back in 1992.

But, inasmuch as it is up and running, the time has come to end our sponsorship.

We continue to support WineTECH/GrapeTECH and the Unified Symposium mad ASEV in the best interests of the industries - grapes and wine - involved.

COPYRIGHT 1997 Hiaring Company
COPYRIGHT 2004 Gale Group