Monday, September 29, 2014

The Myth of "Rich Volcanic Soils" Or How I Learned to Love Molisols.

A lot of Washington grape growers tout the "rich volcanic soils" that our grapes are grown on. There is even a writer in the area writing a book about it. Perhaps that isn't the case and a little clarification is necessary.

Yes, the occasional volcano blows up to the west in the Cascade Mountains and some ash blows eastward. Does this make up our soils? Big ole Mt. Mazama gave us about 12 inches of new soil but that was about 8000 years ago. In 1980 Mt. St. Helens deposited about 1/2 inch of dust on the Rattlesnake Hills. Often the wind blows this dust to the west as it did the day Mt. St. Helens covered Portland in ash.

Volcanic soils are called Andisols and occur in the close vicinity of volcanoes. Hawaii, the South Pacific, Japan and even soils within the Cascade Range are known for Andisols. The grapes around Mt. Etna in Sicily are grown on Andisols.

So, if the soils in wine country aren't Andisols, what are they? It turns out the majority of the soils in Eastern Washington are Molisols with some Aridisols. They are less than 1% Andisols.

Molisols are formed by grasslands and you might know that the desert steppe of eastern Washington was at one time a great grassland covered by the native blue bunch wheat grass. The surface horizon was formed by wind-blown (Aeolian) sediments from the retreating glaciers of the ice age with the occasional deposit of volcanic ash for the Cascades.

Aridisols are the desert soils that occupy arid shrublands. They are found in the center of the Columbia Basin (known to many as the Columbia Valley.)

The next time some well-know and often-quoted grape grower spouts off about "rich volcanic soils" you may now correct him. They are Molisols and Aridisols. Sorry, no Andisols.

By the way, Molisols and Aridisols are great for growing wine grapes!

Thursday, September 11, 2014

First Polar Outbreak Portends Ominous Winter

The northeast wind blew ferociously all night last night. You may not have noticed, but we here in Eastern Washington are in the midst of a Polar Outbreak - a weather pattern that reeks havoc with wine grapes in the winter. You didn't notice? That's because the temperatures up north where the cold air comes from are still moderately warm.
Here is what happens. The jet stream makes a big loop up the Pacific Ocean into Alaska, then turns south into Alberta, Canada, the southwest into eastern Washington.
Normally, this big loop misses us and hits Montana, but yesterday and today it is looping further west and hitting us.
Why does this portend a nasty winter? First there is an El Niño developing in the Pacific - good news for California, but bad news for Washington. (Oddly there is a point in southern Oregon that is not affected either way during El Niño/ La Niña.) The jet stream has a wet and dry side. El Niño puts California on the wet side and Washington on the dry side. It is also the time that Polar Outbreaks are most likely to happen and happen strongly. Usually we get two or three of these per winter. This is the earliest I can remember. Because we are on the dry side of the jet stream, next year could be a short water year in the Yakima Basin.
Another serious problem with a Polar Outbreak is that they are often preceded by the Pineapple Express, a strong jet stream directly from Hawaii. This causes the grapes to lose their cold hardiness. Like a giant snake, the jet stream then loops northward in a matter of hours.
The forecast for tonight is 37o. The normal low is 45o and the record low is 35o. If this were winter it would be serious.
What to watch for: if the temperature in Fairbanks, Alaska reaches 40o below this winter, expect a serious Arctic Outbreak.