THE GREAT TERROIR DEBATE IN OREGON: WHICH SOIL IN THE NORTHERN WILLAMETTE VALLEY PRODUCES THE BEST PINOT NOIR

Winemakers want to make sure they have the best soil possible to produce the best wines. The soil is an important part of terroir. A completely updated study of 210 vineyards and 5600 acres in the northern Willamette Valley, the heart of winemaking in Oregon, showed that two soil series are the dominant vineyard varieties, but four other soils have also shown great promise. The two dominant soils are the Jory, an Ultisol developed on 15 million year old basalt bedrock and the Willakenzie, an Alfisol developed on marine sedimentary rocks of the Coast Range. Both soils are very old (over 500,000 years old), well-drained, on side slopes and have a xeric moisture regime. Alfisols have a few more nutrients in them compared to Ultisols. Four other soils with similar features are also being planted on with good results. Laurelwood soil is an Alfisol developed on mainly basalt with some old loess mixed in. Nekia is very similar to Jory (an Ultisol on basalt), but it is shallow (from 50 - 100 cm depth) compared to the Jory. The Yamhill series is developed on basalt and is also old (ultic lower horizons) but it is mainly a Mollisol with a thick A horizon. The Cornelius soil is also an Alfisol but is developed in old loess deposits. Four other soils were noted to be not as good for wine grapes: Peavine (no xeric moisture regime)and Woodburn, Amity and Dayton (not as well-drained and they have too many nutrients because they are on the valley floor developing in Missoula Flood deposits). Our study shows that for the best terroir, the best soils for producing great Pinot Noir wines in the northern Willamette Valley of Oregon are red, old, well-drained and xeric in their moisture regime.