Patty Skinkis/Oregon State University

Crimson clover, an annual legume, growing in a vineyard’s alleyways.

Some researchers are urging wine grape growers to consider planting cover crops between their vines.

Steve Groff, a well-known cover crop consultant and founder of Cover Crop Coaching LLC, told attendees at the virtual Oregon Wine Symposium this week he thinks cover crops are the "future" of vineyards with the potential to increase soil health and yields.

"This is where we're headed," he said, showing viewers a photo with carpets of flowers and greenery growing in a vineyard.

Groff was co-leading the virtual cover crop session Thursday alongside James Cassidy, senior soil health instructor at Oregon State University.

Cassidy said growers trying cover crops for the first time often want a "recipe" of what to plant and when, but he says it's more important growers first understand soil basics.

"It's not about reading a recipe of what to do. It's about knowing how to cook," he said.

Cassidy held up a pinch of dirt, telling viewers it likely contained more than 1 billion living organisms.

These beneficial species, he said, as well as soil nutrients, thrive best when their habitat has the right combination of carbon, energy and a variety of air hole, or pore, sizes.

Microorganisms are healthiest, he said, when their soil habitat has 5% or more organic matter. For every 1% increase in organic matter, according to the researcher, soil can store up to 25,000 more gallons of water per acre. And cover crops add organic matter to soil.

This benefit of cover cropping is well-known; the less obvious but equally important benefit, Cassidy said, is how cover crops change soil's structure.

Soil is about 50% space, or air holes. Water drains faster through large pores and holds longer in small pores, much like how a towel or sponge soaks up water and holds it against the force of gravity. Soil with all large pores is problematic because water drains too quickly, said Cassidy. But soil with all micropores is a problem, too, because it can become waterlogged.

"That's how plants drown," he said.

Cassidy said the best soils have a wide distribution of large, medium and small pores.

And one of the best ways to achieve that is to plant cover crops. Cover crops grow small, medium and large roots, and when the plants decompose, they leave behind complex pore structures.

The root systems also leave behind a kind of "glue" — particles that make the soil more structurally stable, helping prevent runoff and erosion.

Groff, the consultant, added that cover crop use may also decrease the need for other inputs like fertilizer and pesticides.

But Groff warned that cover cropping isn't simple.

"It's hard," he said, naming the cost of seed and seeder equipment, time commitment and lack of knowledge in the relatively young field as potential challenges.

But overall, Groff and Cassidy agreed the benefits of cover cropping outweigh the costs or risks.

"I think that soil health is our future," said Groff.

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