Sunday, May 17, 2009

Managing Our Precious Resource: Water

There's an old saying that good wine is made in the vineyard. To which I add great wine is made by blending. But you can't make any wine without water, at least when you're a grower in Southern California and you don't have old vines that don't need irrigation. With the advent of water restrictions, another dry year and the prospects of global warming, water management is critical. As a grower with a small backyard vineyard the tools I use to determine when it's time to water are 1) looking at the vines (economical, but not very scientific) 2) perhaps a simple tensiometer 3) wait for the Queen who manages our vineyard to plead for the third time to water her vines. I was curious what tools the big boys are using so drove up to Temecula's 100-acre Maurice Carrie Vineyard to meet with Gus Vizgirda, the vineyard manager, winemaker and all-around-good-guy.

The picnic table outside the Victorian farm house had several soil samples in jars. Gus had take the samples, added water, shaken, and allowed the samples to settle, giving him an idea of the composition and percentages of clay, loam and silt in various spots of the vineyard. (Now that's something I can do at home.)

Gus had taken another soil sample and inserted it into a 5ft plastic, see-through tube to the 3-feet level. Pouring water into the tube, he's able to see how deep, and at what speed water is able to penetrate the soil. Gus has found that at his location, he's better off with a very long watering in the beginning of the watering season followed by short waterings later. Because of the initial deep watering, later waterings are able to penetrate the soil better, he said.

Gus' choice for emitters are two @ 1/2 gallon/hour on each side of the vine. Several C-probes, at $2,000/each, are placed 3ft. below the soil surface to measure moisture content and transmit signals to a computer. Gus gets computerized reports showing him green zones and red zones indicating when it's time to water and spray for powdery mildew. (The computer takes temperature readings and calculates when mildew pressure is growing and it's time to spray.) I've heard of other growers who integrate Twitter into such a system so the vines send a tweet when they need water.

Most Temecula Valley growers are on "city water" and coped with a 30% water cut last year. They are likely to face an additional 10% reduction this year. Their land does not include water rights unlike most growers in Ramona (San Diego County) who are on well water. Hence, the investment in water management tools, because you can't make the best possible wine in Southern California without judiciously applying a little water.

What tips and suggestions do you have for managing water use in the vineyard?

1 comment:

Vinogirl said...

PMS is a major concern in all Ca. viticultural regions. Vines don't usually display physical signs of stress, e.g. shortened tendrils, until a good 2 weeks into a deficit situation. We have a pressure chamber (bomb), to monitor vine stress, test weekly and hope our well is deep enough, even in drought years, to cope with the thirsty little so and so's.