While much has remained unchanged in Italy’s hills of Conegliano and Valdobbiadene—they are, after all, a UNESCO World Heritage site—one thing certainly has: the weather.
“With climate change we are subject more to sudden precipitation,” says Umberto Cosmo, the co-owner of Prosecco producer Bellenda Wines. “Having the vines parallel to the hill that will slow down the flow of the water is very important.”
He’s talking about an agricultural technique called contour farming. Cosmo says they began using contour farming in their vineyards in the 1990s. They currently have about 25 percent contoured, and are converting more from downhill rows.
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Contour farming is an old agricultural method that is finding favor in vineyards as part of new sustainability programs that aim to combat the growing effects of climate change. As a nature-based and regenerative agriculture approach, contouring is a sustainable tool to manage water and erosion, but it’s not suitable everywhere. To contour or not to contour? Some vineyard managers are seeking an answer.
The Benefits of Curved Lines
As the name implies, contour farming is the practice of using the contours of the land. The method involves tilling or planting across a slope and building small ridges at right angles to the land’s natural slope.
The goal is to stay on a constant grade, or a slope that is not erosive, since farming on sloped land can accelerate erosion, explains Allen Thompson, a professor emeritus at University of Missouri’s College of Agriculture, Food & Natural Resources. A good visual comparison, he suggests, are isobars on a weather map.
The ridges themselves will also have a slope, albeit a shallow one, in order to control the speed of the water. The shallow ridges slow down water runoff by creating a new pathway for it to travel. In turn, slower water means less soil erodes as it moves. “When that water is trying to flow straight downhill, that ridge will intercept it, and then its grade or slope is slow enough that it prevents the water from scouring the hill,” explains Thompson.
When used in a vineyard, the rows of vines are likely to be put on a contour. Contouring differs from terracing—terraces are much taller—although terraces will often incorporate contouring as well, says Thompson. Terracing is expensive and means doing actual construction; contouring, on the other hand, does not. “Contouring is probably one of the cheapest [methods] that you use in agriculture to help control erosion and control runoff,” he says.
Another benefit of contouring for vineyards is more efficient drip irrigation. Drip irrigation typically uses very low water pressure, which is impacted by changes in elevation. With contour planting, vines are close to the same elevation, which allows for more consistent water pressure. Even modern drip systems that have pressure compensating emitters are helped by contouring. “If you can keep pretty much the same elevation across a particular row of plants, it makes it easier even for those compensating emitters to be effective,” says Thompson.
The Challenges of Contour Farming
However, contour farming is not a good choice for either very flat or very steep land—it’s best for land with a grade from three percent to eight percent, says Thompson.
Historically, contour farming has mostly been used in arid landscapes, he says, and times of drought. For example, it was researched during the Dust Bowl era in the U.S and in South Africa in the 1940s. Studies found that contouring helped with water conservation in addition to reducing erosion and slowing water movement through the soil.
But back then, it was a difficult method to use as the contours need to be consistent. If the contours are uneven, they won’t be as effective because they could end up creating areas where water pools. Now, agriculturalists can use precision farming technologies, including laser systems and GPS, to map out contours.
The bigger problem for established vineyards, however, is that the switch to contouring means pulling out all their vines. In addition to plant loss, that land is out of production for the duration of the work.
“Contouring is probably one of the cheapest [methods] that you use in agriculture to help control erosion and control runoff.” – Allen Thompson, University of Missouri
In Chile’s Maule Valley, Santa Rosa de Lavaderos grows Cabernet Sauvignon, Syrah, Carmenère, and País using organic methods. Winemaker Paul Mc Rostie, who uses the grapes to make Kodkod Wines, says that some of the vines are planted using contouring for water control.
One drawback, Mc Rostie points out, is that the trellis system—vertical shoot positioning—is less stable because the wires are also curved along the contour instead of pulled straight as they would be in a conventional straight row. “The farm workers don’t like it very much,” he says. “It needs some fixing and reinforcement and you have to be more careful or you break the poles in between.” Cosmo uses a double arched cane trellising system at Bellenda, but according to Thompson, there isn’t an optimal trellis system for contour farming.
Contouring as Part of Sustainable Practices
Owner and viticulturist Johan Reyneke says that Reyneke Wines in Stellenbosch, South Africa, moved to organic and biodynamic farming practices in 2000. For Reyneke, it’s important to use sustainable and regenerative farming practices to counteract climate change.
They build contours—furrows two to three meters wide with a very gentle slope—at the end of their vine rows to harvest water runoff (which is redirected to farm dams) and to prevent soil erosion. The vines are planted between the contours, unless the slope is too steep. In those cases, they maintain wilderness areas instead.
The contours also act as biodiversity corridors. By planting endemic flora at the bottom wall of the contours, they create a habitat for animals and a kind highway system on their farm. “If you’re a mouse or a porcupine, you can run across the entire farm without leaving the safety of your natural environment,” says Reyneke. “It’s a bit like the concept of the English hedgerows of olden times.”
Combining contouring with grasses or cover crops is a good approach, says Thompson, because the vegetation helps keep soil in place and will also maintain the contours. Mc Rostie also recommends contouring as a complement to cover crops and other methods of soil protection.
Corso agrees that grasses are a very effective method of protecting soil, which they also do in concert with contouring. They noticed erosion under the vines during rainy springs, so now they only cut the grass sporadically. “I travel quite a lot and I still see that in many countries there is a lot of work under the vineyard, so no grass at all,” he says.”I think that is something that should change in the future.”
One of the challenges of being part of a UNESCO site is that Bellenda can’t change anything without permission. But they’re continuing to experiment with contouring at more of their vineyards. Cosmo knows of other producers in the region doing the same, even though contour farming, he says, “wasn’t in our tradition in the past.”
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Danielle Beurteaux is a writer whose work has appeared in many outlets, including The New York Times, Eos, Scientific American, and Wine Enthusiast. She also has a Level 2 WSET Award in Wines.