The Spill: To till or not to till

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Some may think that a bottle of delicious wine starts with a knowledgeable, experienced winemaker using expertly grown wine grapes. That may be part of the equation, but ask the winemaker and the answer is that yummy wine starts in the vineyard; more specifically the soil.

“You can’t make great wine without healthy soil,” said Julie Cooper, associate winemaker for DuMol in Healdsburg. “It’s vital.”

Cooper was among about 40 people – winemakers, vineyard managers, farmers and soil geeks – filing through rows of grapevines at MacLeod Family Vineyard in Kenwood during a soil tillage management workshop sponsored by Sonoma Resource Conservation District (RCD) on June 19.

The vineyard at the Indian Springs Ranch is the site of a two-year experiment in soil moisture and health being conducted by Keith Abeles, water resources specialist at RCD, Josh Beniston, soil scientist and agriculture program coordinator at Santa Rosa Junior College, viticulturist Mark Greenspan, president of Advanced Viticulture in Windsor, and John MacLeod, owner of the vineyard.

Abeles was interested in learning more about the effects of tilling in vineyards on soil moisture and health, but in his quest for research he found little.

“I wasn’t finding anything scientific. There wasn’t really anything about tillage for grapes,” Abeles said.

He found some reports related to farming in the Midwest, but it wasn’t relevant given the vast difference in climate and what is being grown. Even information on tillage and farming in California’s central valley isn’t very useful given that the climate and terrain are so different in Sonoma County and the surrounding wine grape growing counties.

Abeles set out to gather his own data securing a grant from the USDA-National Resources Conservation Service. The test is to determine if tilling or not tilling – or alternatively a combination of both – is better for soil moisture and health, which leads to healthier plants. Vines, in this case, and that leads to better wine.

The full results are not in, and Abeles said the data so far shows there is little difference between the three techniques. There are proponents for each though, with some arguing that the no-till way will win in the long run.

Will Bucklin, owner and manager of Bucklin Old Hill Ranch in Glen Ellen, is a fan of no-till.

“There’s less use of carbon and more retention of carbon in the soil,” he said.

More carbon sequestration is better for the environment, and soil organic carbon is a measure of the amount of organic matter in soil moisture, he said.

In the MacLeod vineyard, Abeles and the team selected 100-foot sections for each method to be tested – tillage, no-tillage, and alternate row tillage, which means that one row is tilled, and the row next to it is not – with 10-foot breaks between each method section. The methods were replicated in nearby sections for scientific data gathering and soil moisture probes were installed throughout with data being collected every 30 minutes of every day since the spring of 2017 when the project began.

Greenspan helped whittle down the massive amount of data into a chart they handed out to workshop attendees. This past winter threw a curveball to the program, but nature happens, and it’s still part of the study, Abeles said. Looking at the chart, the full till method shows more moisture than does the no-till and alternate-row till, but as weeks pass, and the rain tapered off the numbers come in with very little difference. The no-till soils showed slightly less depletion rate, but not significant enough to call it conclusive, Abeles said.

They will continue to take readings of moisture through the end of the season and are awaiting results of the soil health tests. In the meantime, Ables has another test site at La Crema Estate’s Saralee Vineyard. More workshops are planned, and have been well attended.

“We’ve had incredible turnout,” Abeles said. “There’s a lot of interest in this.”

For more information on Sonoma Resource Conservation District go to

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