Why do winemakers use no-till farming?
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Dear Dr. Vinny,
On a recent vineyard tour, I kept hearing the phrase “no-till farming.” I thought tilling was good for grapevines. What’s the deal?
—Amanda, Roseville, Calif.
Dear Amanda,
Great question! For years, winegrowers have paid attention to the groundcover between the vineyard rows. Some even planted specific plants—particularly grasses and legumes—which add nutrients to the soil and suppress weeds, along with reducing erosion and encouraging biodiversity and a healthy soil microbiome. Before the groundcover could threaten to compete with the vines for water in the spring, many growers would then till (break up the soil and turn it over) between the rows.
For years, tilling (in addition to weeding) was thought to be a good way to aerate and warm the earth. It was thought that mixing the cover crop vegetation, especially legumes, into the ground could add nutrients, particularly nitrogen, into the soil. The resulting mulch, the pro-till thinking goes, can also act as a sun barrier and erosion control when the rains start.
But as farming practices developed, things like drip irrigation gave vintners more control, and new technology to measure the amount of water in the soil gave more data points. Over time, the thinking evolved. Now, with no-till or low-till approaches, which leave the cover crops undisturbed (outside of some possible mowing), growers can cut down on soil disturbances, which is now believed to improve soil health.
When soil is disturbed, it loses its sponge-like quality, making it less effective in absorbing and retaining water and nutrients. Tilling also disrupts the soil’s microbiome, possibly killing the good microbes and insects.
No-till farming maintains the surface vegetation and lends itself to the regenerative farming philosophy of being sustainable and minimizing environmental impacts. The process of tilling releases carbon dioxide from the plants into the atmosphere, and you also have to consider the emissions from the tractors used for the tilling passes. Reducing labor is another advantage. There are also growers that have adopted a hybrid approach of low-tilling, or tilling alternate rows in alternate years.
—Dr. Vinny
