Even casual home cooks wouldn’t substitute cilantro for rosemary in a roast, or sprinkle sage into a sauce that calls for basil. Through hard-won experience, we all know that ill-thought out swaps radically change results, and they rarely result in an upgrade.
Our understanding of the way cover crops change the quality of crops like grapes in the field is decidedly less evolved and nuanced, but we’re learning more every day.
Advocates say that cover crops help feed soil life, improve soil structure by stabilizing it, reduce soil compaction and help soils absorb heavy rains more efficiently, which in turn helps reduce erosion and nutrient runoff. A small increase goes a long way: a 1% increase in organic soil matter can help it absorb 20,000+ additional gallons of water per acre, a super power in an era of extreme weather conditions.
In addition, they help soils retain water more effectively, which can be a boon in drought conditions. Cover crops can also attract beneficial insects that in turn help eliminate pests and diseases, without the need for chemical intervention.
Winemakers who have relied on cover crops for decades say that their understanding of their diverse benefits has deepened over time.
“Organics and cover crops have been part of our program since the vineyard was established in the 1990s,” says Jacopo Dalli Cani, head winemaker at McHenry Hohnen in Margaret River. “The idea was to avoid the use of herbicides and pesticides and to manage competing weeds and increasing soil carbon.”
Beyond the benefits for soils and crops, the planting of cover crops help remove carbon from the atmosphere and provides snacks and shelter for insects, birds and other wildlife.
While there are still many farmers who doubt the efficacy of cover crops, a recent meta study conducted at the Indiana University School of Science compiling data from more than 100 field trials around the world found that cover crops increase yield by 2.6%. Cover crop adoption is certainly on the rise. Between 2017 and 2022, the total number of acres of cover crops planted in the U.S. increased 17% from 15.4 million to 18 million, according to the USDA.
Many of the cover crops that vintners plant double as eye-candy, and do what you’d expect them to (like attract pretty flying things).
“I chose a mix of dwarf, autumn beauty and black sunflowers, phacelia, sweet clover, blue flax and vetch,” Ryan Decker, viticulture and grower relations manager at Clos du Val in the Napa Valley, says of their pollinator-friendly insectary crops planted every tenth row. “It should look pretty cool too!”
But other cover crop choices, while less visually stunning, allow growers to create healthier soils without the help of chemical fertilizers, herbicides or machines, boosting vine health – and ultimately, the quality of wine in the glass.
While there is still a lot to learn about which cover crops are ideal for site-specific terroirs, winemakers are deploying a mixture of flowers, legumes and brassicas in their vineyards, much as experienced chefs utilize specific spices in recipes.
Grains and brassicas for soil structure
Growers are finding that cover crops can radically change the quality of their soils.
“For our heavier clay soils I like to use triticale,” says Decker. Triticale is a hybrid of wheat and rye, and it “produces a huge root system that helps remove some of the excess moisture and breaks up the clay.
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