This winter was the wettest on record. I've had some growers ask me or joke "so we won't need to irrigate this year, right!?". Well, as most of you probably know, that is not the case at all. There is a finite amount of water storage in our soils, referred to as water holding capacity (WHC), defined per depth of soil, but also spanning the depth of the effective root zone. Beyond that WHC, any additional moisture will either run off, or percolate below the root zone. Soils in the north coast were essentially at field capacity in December of 2016, so all of that heavy rainfall did not contribute one drop of additional moisture storage to vineyard soils. It's really the spring rainfall that dictates how we manage vineyard water. Late spring rainfall forces us to combat that extra available moisture through vineyard management practices, such as delayed suckering and thinning, cover crop and floor management, and possibly less fertilization.

Next month, take a look at my article on the subject in the June issue of Wine Business Monthly, where I go into greater detail. In that article, I stress the importance of soil moisture management. There are new technologies that are bringing us the ability to automatically monitor vine water status (stress). I feel that some of the best are still to come, now being field-tested. We are participating in the testing of one of the devices and are also involved with another of them. Despite our increasing ability to monitor vine stress, the need for soil moisture monitoring is not reduced by any means. With knowledge of where root activity is occurring and where moisture continues to be available, soil moisture monitoring allows us to apply irrigation later into the growing season. Oftentimes, we've been able to dry farm vineyards previously irrigated. Also, continuous electronic soil moisture monitoring allows us to determine the depth of each irrigation and precisely how many days elapse for vines to extract that moisture. No modelling - just highly repeatable results from irrigation-to-irrigation and from season-to-season.

I gave a presentation recently at the Sonoma County Winegrower's Sustainability Field Day. Check it out by clicking here.

Mark Greenspan

For more information about soil moisture monitoring, contact Mark at mark@advancedvit.com or JT at JT@advancedvit.com or 707-838-3805.