Category: Archived Articles

By: Kirk Williams, Lecturer-Texas Tech University

Nutrient management is a critical practice to have a healthy and productive vineyard.  Nutrition management in grapevines is a long-term process where nutrients can be added over time and the effects of these additions monitored over time as well.   Grapevines do not require large amounts of nutrients and the nutrients can be added in response to needs identified by soil and tissue samples

  While soil samples can give us great insight into the soil at a vineyard site they do have limitations in established vineyards.  Grapevines have a deep and extensive root system that can exist at deeper depths than common soil testing equipment can collect from.  Also, soil tests indicate relative availability and this level is not always reflected in nutrient status of the grapevine.  Soil testing in vineyards should still be done in established vineyards but a sample every three to five years is adequate to understand what is happening in your vineyard soil. 

  In season nutrient management begins with assessing the nutritional status of the grapevine.  The most common way of evaluating the current nutritional status of grapevines is through tissue analysis.  Tissue samples can be taken at bloom time or at veraision.  Sampling could also occur at both bloom time and veraision which can help you assess your in season nutrient management program.   Areas where observable problems exist should be sampled separately from areas where growth is normal.

  Tissue samples have historically been petioles but recently whole leaf samples have been utilized.   Collecting a good representative sample is critical to getting accurate results.  If you are collecting petioles, you will need 50 to 100 petioles from each block. If you are collecting leaves you will need 25 leaves per acre up to a maximum of 300 leaves per block.  Many laboratories will wash tissue samples but that will require quick shipping. 

  So, it may make sense to wash your own samples.  A few drops of phosphate free liquid detergent can be added to a basin with distilled water.  Samples should then be rinsed with distilled water for no more than 10 seconds.  Rinsing longer than 10 seconds may wash out some of the nutrients.   Samples can be dried and then shipped to the lab for processing and testing. 

  Oftentimes soil and tissue tests are deemed precise because they are actual numbers determined by a lab.   While they were determined by a lab, there are many factors that go into a fertility program for a vineyard.  There are not many black or white, right or wrong answers in vineyard fertility management. There is only a continuum of possibilities all of which are impacted by the environmental conditions of the year, the soil, the microbial population in the soil, fertilizers applied, cover crop interactions as well rootstock and scion responses to all of the above.   

  For example, in an extremely dry year, even with adequate boron in the soil and foliar applied boron, your plant tissue samples may show you are short on boron.  Low soil water status reduces boron release from organic matter and boron uptake through reduced boron transport that occurs by diffusion and mass flow to absorbing root surfaces.  The next year, under normal soil moisture conditions, your tissue samples may show adequate boron even though you did not fertilize with boron.   

  Use the soil tests and tissue tests as guides over time for your fertility program but don’t focus too much on the actual numbers, focus on the trends.  Also, don’t forget to use your eyes to see the impact of your fertility program.  

  Generally, nutrients needed in large quantities, such as Nitrogen and Potassium, are applied to the soil.  Nutrients needed in small quantities such as zinc and boron can be effectively applied to the foliage of grapevines.  We will focus on foliar fertilization for the rest of this article.  Boron and zinc can impact fruit set if they are low and are recommended to applied prior to bloom.  This timing is usually critical for prevention of many fungal diseases and these nutrients, if needed, can easily be added to a pre-bloom fungicide spray. 

  Each individual nutrient capabilities for mobility within the plant can impact how effective a foliar nutrient application is.    Mobile nutrients such as nitrogen, magnesium, phosphorus and potassium are moved in the phloem from the older leaves towards the growing tip.   Deficiency symptoms will therefore occur on the older leaves.  Immobile nutrients, such as boron, calcium and iron, are not moved around in the phloem.  Deficiency symptoms will occur in younger leaves near the shoot tip. 

  In addition to nutrient mobility within the plant, nutrients can differ in their absorption through the leaves.  Rapidly absorbed nutrients include the urea form of nitrogen, potassium and zinc.  Moderately absorbed nutrients include calcium, the sulfate form of sulfur, phosphorus, manganese and boron.  Slowly absorbed nutrients include magnesium, copper, iron and molybdenum. 

  Zinc is a nutrient that is partially mobile and is rapidly absorbed through the leaves so it is a good candidate for foliar fertilization.  In contrast, iron is immobile in the plant and is slowly absorbed through the leaves so Iron is a not a good candidate for foliar fertilization. 

  Best practices for foliar fertilization include application during the cooler parts of the day, including a high-quality surfactant, good coverage of the grapevine especially the undersides of leaves and applications to young actively growing tissue. 

  Nutrient management in grapevines is an important management tool in having a productive vineyard that produces high quality fruit.  Regular tissue sampling is required year after year to get feedback on your nutrient management program to fine tune nutrient applications to each vineyard site.  Foliar nutrient applications can be an effective management tool especially for micronutrients.

  Kirk Williams is a lecturer in Viticulture at Texas Tech University and teaches the Texas Tech Viticulture Certificate program.  He is also a commercial grape grower on the Texas High Plains.  He can be contacted at kirk.w.williams@ttu.edu

Resources

  Singer, S.D., Davenport, J.R., Hoheisel, G., & Moyer, M.M. 2018. Vineyard nutrient management in Washington State.

  Western Plant Health Association.  Western Fertilizer Handbook.  10th Edition.  2023. Waveland Press, Long Grove, IL

By: Becky Garrison

This year marks the 40th anniversary of Oregon’s Willamette Valley AVA, which runs from Portland in the North to Eugene in the South. According to the Willamette Valley Wineries Association’s website this AVA consists of 931 vineyards and 736 wineries that represent a total 3,438,000 acres. Currently this AVA has 11 nested AVAs that contain two-thirds of the 1,110+ wineries in Oregon.

  While wine has been made in the Willamette Valley since the 1880s, initially this land was considered too cold and wet to grow great grapes even though it is close to the same latitude as Burgundy, France. In 1965, David and Diana Lett picked up on this distinction and planted 3,000 Pinot noir vines in 1965 at The Eyrie Vineyard near Dundee. Other early wine pioneers included Dick Erath, the Knudsens, and the Sokol Blossers.

  A key factor in the early development of the Willamette Valley was the passage in Oregon of the Land Conservation and Development Act (Senate Bill 100). Signed into law on May 29, 1973, this bill set aside land for future agricultural use.

  This AVA’s last recorded harvest resulted in 84,328 tons, which represents 73.5% of the state’s total crop. The majority of grapes planted are Pinot noir (70%) followed by Pinot gris (16%) and Chardonnay (7.5%). In recent years, some growers have been experimenting with other varietals like Pinot blanc, Riesling, Melon, Gewürztraminer, sparkling wine, Sauvignon blanc, Syrah, and Gamay..

  The region’s general attributes that make this valley ideal for growing cool climate grapes include the protection provided by the Coast Range mountains to the west, the Cascade Mountains to the East, and a series of lower hills at the extreme north of the valley. Drew Voit, Owner/Winemaker, Harper Voit Winery (McMinnville, OR) has been making wine for over twenty-five years, as well as consulting with other wineries situated throughout the Willamette Valley. In his estimation, the Willamette Valley represents the Goldilocks zone in terms of climate and latitude. “We have a particularly long growing season with a cool climate, mild winters, warm and dry summers.”

  Furthermore, the unique characteristics of each of the 11 nested AVAs allow for a surprising wide range of wine expressions. As Voit observes, “There’s diversity even within neighboring vineyards. You really have to listen to each vineyard and embrace the terroir of that particular site.”

  From 2005 to 2006, six sub-AVAs were formed: Dundee Hills, Yamhill-Carlton, McMinnville, Ribbon Ridge, Chehalem Mountains and Eola-Amity Hills.

Dundee Hills AVA: The Dundee Hills AVA has the distinction of being where the first grapes in the Willamette Valley were planted, and it remains the most densely planted locale in Oregon. The region’s Jory soils are formed in colluvium derived from basic igneous rock resulting in well-drained very deep soils. This soil was named after Jory Hill, a town in Marion Country named after the Jory family who settled this area in 1852. Voit states how this AVA’s soil produces powerful red fruit with strong floral notes and a classic balance.

Ribbon Ridge AVA: With only 500 planted acres, this AVA nestled within the Chehalem Mountains AVA represents the smallest AVA in Oregon, as well as one of the most prestigious wine growing regions in the world. Most vineyards in this AVA are protected climatically by the larger landmasses surrounding it, and are dry farmed due to the lack of aquifers. The area is comprised primarily of the Willakenzie series of well-drained and moderately deep sedimentary soils that are ideal for growing complex Pinot noirs with earth notes of dark cherry and rose petal.

Yamhill-Carlton AVA: Situated at the foothills of the Coastal range, the Yamhill-Carlton AVA, contains around 60,000 acres centered around the hamlets of Carlton and Yamhill. This region was known for logging, nurseries, fruit tree orchards, wheat fields, and logging until 1974 when Pat and Joe Campbell and Roy and Betty Wahle planted Elk Cove Vineyard and Wahle Vineyard respectively. In Voit’s estimation, this region produces intense, dark and rich grapes similar to Ribbon Ridge, though he adds that the wines from Yamhill and Carlton may have similar marine sediments, but they possess different and distinctive aromatic tones.

McMinnville AVA: This AVA begins a few miles to the west of McMinnville and then extends approximately 20 miles south-southwest toward the mouth of the Van Duzer Corridor. This AVA’s most prominent geological feature is the Nestuca Formation, a 2,000-foot bedrock formation consisting of weathered volcanic and sedimentary soil that sits on top of marine bedrock. Pinot noir grapes harvested from this AVA tend to exhibit darker fruit flavors and a strong backbone of tannin rounded out by earth, spice, and mineral notes due to the AVA’s drier and cooler temperatures.

Chehalem Mountains AVA: This AVA’s history dates back to 1968 when Dick Erath purchased 49 acres on Dopp Road in Yamhill County that he named Chehalem Mountain Vineyard. He was joined by other pioneers in the 1970s, including the Adelsheim and Ponzi families. The Chehalem Mountains AVA was formally approved in 2006. The Chehalem Mountains are made up of several spurs, ridges, and hilltops with the tallest point Bald Peak, at 1,633-feet above sea level. These features shelter the vineyards from the high winds that blow south through the Columbia Gorge. The soils found throughout this AVA consist of marine sedimentary soils, volcanic soils, and a series of loess called Laurelwood, which is a a geologically younger windblown silty soil of glacial origin.

Eola-Amity Hills AVA: While this agricultural history of this area near Salem dates back to the mid-1850s, winemakers like Don Byard of Hidden Springs didn’t discover this region as an ideal place for growing high-quality wine grapes until the 1970s. The soils of the Eola-Amity Hills consist predominantly of volcanic basalt from ancient lava flows. This feature when combined with alluvial deposits and marine sedimentary rocks results in a rockier and shallower well-drained soils that result in small grapes that are highly concentrated. As Voit observes, this AVA, is impacted by the Pacific Ocean influence where the winds rapidly cool the valley at night, thus helping the grapes retain their acidity as they ripen. “This produces wines with lots of spicy, savory and other non-fruit characteristics that are very compelling and distinctive.”

  From 2019 to 2022, five additional nested AVAs were formed: Van Duzer Corridor, Tualatin Hills, Laurelwood District, Lower Tom AVA and Mount Pisgah, Polk County, Oregon.

The Van Duzer Corridor AVA: This AVA, which went into effect in 2019, consists primarily of marine sediments is a natural break in the Coast Range results in afternoon winds that are 40 to 50 percent stronger when compared to other Willamette Valley AVAs. Voit works extensively with this AVA that he describes as the most Pacific Ocean influenced place in the Valley. “If a vineyard is in the windward blast zone of those strong breezes, there’s rapid cooling in the evening and howling winds. The winds are a little more delicate on leeward side of the hills.” This wind variability leads diverse wines that are both compelling and distinctive with an overall a cooling afternoon effect that dries out the vine canopy and degrees the presence of fungus, along with thickening the grape skins, which produces and abundance of tannin and anthocyanins (color).

The Tualatin Hills AVA: 2020 marked the approval of the Tualatin Hills AVA, a 15-mile stretch of land situated in the far Northwestern corner of the Willamette Valley that is is defined by the watershed of the Tualatin River with an elevation range between 200 and 1,000 feet. This AVA has a lower rainfall, cooler springtime temperatures and more temperate and drier weather during fall harvest as it’s sheltered by the Coast Range and Chehalem mountains. In addition, this AVA features the largest concentration in Oregon of Laurelwood soil, which is a windblown volcanic soil mixed with basalt (loess) deposited by the Missoula Floods at the end of the last ice age.

Laurelwood District AVA: In this same year the Laurelwood District AVA, which comprises more than 25 wineries and 70 vineyards, got approved as a result of petitioning by Ponzi Vineyards and Dion Vineyards. This AVA nested within the Chehalem Mountains AVA comprises more than 25 wineries and 70 vineyards with Laurelwood soil as the predominant soil found on the north- and east-facing slope of the Chehalem Mountains. The Laurelwood District AVA encompasses over 33,000 acres and includes the highest elevation in the Willamette Valley, at 1,633 feet. Laurelwood soil is composed of a 15-million-year-old basalt base with a loess (windblown freshwater silt) top layer accumulated over the past 200,000 years and at depths of 4’ to 0” depending on the elevation.

Lower Long Tom AVA: The next AVA to be approved was the Lower Long Tom AVA, which was established in November 2021 and is situated at the southern Willamette Valley. The AVA’s 24 vineyards are located on stream-cut ridge lines running east to west This AVA is situated within the west side of the Lower Long Tom Watershed and dominated by Bellpine soil. This term is used to describe moderately deep, well drained soils that are formed in the colluvium and residuum derived from sedimentary rocks. This region tends to have hotter days and cooler nights with more planting at higher evaluations. Voit observes how this combination tends to produce intense exotic wines that are unlike anything in the valley.

Mount Pisgah, Polk County, Oregon:  The latest AVA is Mount Pisgah, Polk County, Oregon AVA established in June 2022. Located 15 miles west of Salem, Oregon, this AVA is defined by the rain shadow of Laurel Mountain to the west, a mild influence from the Van Duzer winds, and the warmth of the Willamette River. While this is the Valley’s second smallest AVA at 5,530 acres, it’s also one of the most densely planted AVAs was 584 acres planted with Willakenzie, Bellpine, and Jory, along with some Nekia soils.

The Future of Willamette Valley Wine

  Even though the number of wineries in the Willamette Valley has doubled since 2005, most wineries fall into the boutique category producing under 5,00 cases a year with many of the vineyards and wineries remaining family owned and operated. Prior to 1990 only two major Pinot noir clones represented the vast majority of Pinot noir grapes produced in the Willamette Valley Since then, these vineyards now plant over a dozen varieties of Pinot nor clones.

  As a testament to this region’s commitment to sustainability and regenerative agriculture, Oregon produces 1% of wine made in US but is home to 52% of Demtmer Certified Biodynamic wineries. Other similar initiatives include Salmon Safe, which promotes products made without pesticides or causing runoff that would harm salmon and LIVE (LoW Impact Viticulture and Enology) certification of sustainable practices.

  In Voit’s estimation, the quality of vineyard farming and winemaking has exponentially grown and expanded resulting in wines with fewer technical flaws. “This is partly because the industry is older. But also, climate change put us into a position where we need to understand how to deal with very difficult seasons,” Voit says.

  In celebration of this region’s bounty, the International Pinot Noir Celebration was launched in 1987 as an annual summer celebration held in July that brings together international Pinot Noir producers, Northwest chefs, and wine aficionados for a celebratory educational weekend. Also in 2000, a group of Oregon wineries launched Oregon Pinot Camp, a weekend of presentations, seminars, and tastings dedicated to Pinot Noir. While this event was designed as a one-time event but has since become an annual summer event.

  As a sign of the region’s push towards diversity, the Willamette Valley is host to the Asian American Pacific Islanders Food and Wine Fest in May, the Queer Wine Fest in June, and the Women in Wine: Fermenting Change in Oregon Conference in July. Other Willamette Valley wine events reported in earlier issues of The Grapevine Magazine include Women in Wine (May/June 2023) and Alt Wine Festival (March/April 2023) with upcoming events posted at the Willamette Valley Wine’s website at https://www.willamettewines.com/things-to-do/events

By: Cheryl Gray

No vineyard wants to watch its profits disappear. Yet, left undetected, pests can feed and multiply on the fruit, vine, leaf, root and even the soil of vineyard plants. While many of these threats are undetectable to the naked eye, the end result is all too visible. Pests multiply, spread disease and ultimately cost vineyards money through lost crops and vineyard plants.  

  Scientists have long considered what methods work best for grape growers who want to protect their crops without harming the environment. Multiple studies have been published, including those from the National Center for Biotechnical Information, which is under the umbrella of the National Institutes of Health. Those studies point to multiple defense strategies, specifically, ways to increase the populations of natural predators as well as the controlled use of biochemicals. These methods aim to destroy microorganisms and pests by targeting their ability to reproduce. The first and most important rule of engagement is knowing the enemy. 

  Among the most destructive pests for vineyards are mealybugs. Experts say these culprits can travel from vineyard to vineyard, sometimes on equipment, vineyard workers or by whatever means they can hitch a ride. The first stop for these pests is usually the vine trunk wood, where they set up during the winter. As early as spring, the mealybugs make their way onto the canopy. Before long, they wind up on the grapes, where they infect the fruit with egg sacs and larvae. Left uncontrolled, mealybug infestations can not only reduce crop yield but can also lead to plant stress and, ultimately, plant death.

  Scientists say that natural enemies of these vineyard wreckers include a predator beetle known as the “mealybug destroyer.” Its scientific moniker is Cryptolaemus Montrouzieri. Another natural predator is a parasite known as the Anagyrus wasp. Both are produced by the millions each year by a California cooperative, Associates Insectary, which specializes in integrated pest management systems.

  Associates Insectary, founded in 1928, brands itself as the only producer of the mealybug destroyer beetle in the United States. The co-op, headquartered in Santa Paula, California, says it has the capability to ship these and other beneficial insects not only to its regional customers but also to global markets throughout North America, Central America and Asia.

  How does IPM work in the vineyard using natural predators? For mealybug control, the battle is all about appetite. The mealybug destroyer beetle basically eats through an infestation of mealybugs, feasting on every stage, from egg sacs to larvae to fully grown pests. The female beetles lay more than 400 eggs, making for a ready army to combat mealybugs.

  Unlike the Anagyrus wasp, in which only the female wasps attack mealybugs (by laying eggs inside them), an entire “family” of mealybug destroyer beetles – male, female, juvenile and adult beetles—literally feed on these pests. Many IPM programs use a combination of the destroyer mealybug beetle and the parasitic wasp to fight mealybugs.

  Another benefit to deploying mealybug destroyer beetles in the vineyard is that they go undetected by ants, which have a symbiotic relationship with the mealybug. Again, it is about one insect feeding off another. Ants consume the honeydew that the mealybug secretes, the same honeydew that can destroy grapevines. In exchange for an unending food source, the ants defend mealybugs from other predators – all except the mealybug destroyer beetles. 

  Controlling the ant population that defends its mealybug “meal ticket” is a separate challenge for vineyards. Among the most destructive ant species to vineyards is the Argentine ant, which became more prevalent in California vineyards during the late 1980s. Containing an ant population in the vineyard usually requires a controlled chemical application, including bait systems and spray options.

  The Entomological Society of America (ESA) has published studies about the Argentine ant and its impact on vineyards, particularly in California. As the largest organization of its kind in the world, the ESA is focused on serving the professional and scientific needs of entomologists and individuals in related disciplines. This, of course, includes grape growers who need to know how to rid their vineyards of pests without harming the environment.

  In the case of Argentine ants, experts say it is important to recognize that ant colonies operate with a hierarchy all their own. While chemical sprays can kill or repel forager ants, the ones that go out for food, those ants are easily replaced with other foragers. Moreover, entomologists note that foraging ants comprise only a small number of ant colonies. This means that spray applications may be somewhat limited in that they are not likely to affect either the queen ants or larvae protected within the ant colonies. The other downside of sprays is that some chemicals can break down within 30 days and harm beneficial insects and the environment.

  Experts say that baits offer an alternative to sprays. Many contain a slow-acting insecticide with the idea that once an ant comes in contact with the bait, it will bring that bait back to the nest, expose it to other ants and, as a result, more ants die. The added plus is that the small amount of insecticide in baits is unlikely to impact either the environment or the natural predators that attack mealybugs and other pests. 

  Suterra is an Oregon-based company that specializes in providing a comprehensive IPM program that includes controlling ants in the vineyard with bait deployment. The type of bait and overall treatment is contingent upon the species of ant being treated and the location of the vineyard.

  Suterra produces hundreds of products that are used by its agricultural clients worldwide, including more than 400,000 acres just in the state of California. Part of its lineup includes products manufactured to disrupt the mating pattern of mealybugs by imitating chemicals known as pheromones. Pheromones are naturally occurring chemicals emitted by organisms that allow them to connect within the same species. The chemicals serve multiple functions, including searching for food sources, identifying potential dangers and finding a potential mate.

  Suterra’s Celada™ VMB vapor dispenser works by deploying a continuous synthetic pheromone release that is designed to disrupt the mating pattern among mealybugs. The idea is to confuse the males by keeping them away from the females of the species. The Celada™ VMB vapor dispenser lasts for a full year and is designed to blend into the vineyard with its unique color and shape. Suterra has other products designed to disrupt the mating patterns of mealybugs, such as CheckMate® VMB-F, a sprayable microencapsulated formula and CheckMate® VMB-XL, a membrane dispenser. The active ingredient in both products is a synthetic replica of the sexual reproduction pheromone of the mealybug.

  When vineyards consider what equipment to use to combat pests, multiple factors come into play, such as vineyard size, specific needs and, of course, how much of its budget is devoted to pest control. Spray Innovations has answers. The company,

headquartered in Grand Island, Nebraska, not only services the cattle industry but also other agricultural sectors, including grape growers. It has been

operating for some 40 years. Chris Whiting is the sales manager for the company and shares details about some of its popular products and how they save time and money for clients.

  “Our most popular sprayers for vineyards are our 10-nozzle dual volutes,” Whiting said. “This volute allows the grower to drive down the row and spray both sides with one pass, reducing time in the field. We have several models available in our Little Hercules engine-driven line (rope or electric start versions available) and our PTO-driven line.”

  He went on to share, “Our sprayers are all built in-house at our Grand Island, Nebraska location. We fabricate 90 percent of the parts that go into our sprayers, which cuts down on costs. We sell most of our sprayers directly, so there is no middleman, and we can keep the cost down. Our frames are powder-coated and include a 10-year warranty. Our volutes are all made with galvanized sheet metal, which is more rigid and can take more abuse than volutes made out of plastic.”

  Customers of Spray Innovations include Krista Hartman, co-owner of Red River Wines and Provisions at the Hartman Vineyard in Sadler, Texas. She gives the Spray Innovations P-D15-611 Mist Sprayer a “thumbs up” for performance. 

  “The fine mist and powerful fan system deliver uniform and thorough coverage with all my spray program products,” Hartman said. “I love how I can turn off either volute individually for end rows or a specific target area if needed. This was a big investment for my small vineyard operation, and well worth it. I save time, use less product, feel safer while spraying and keep my canopy as healthy as the elements allow, thanks to this terrific machine.”

  Whether using chemical applications or natural predators, grape growers can deploy an arsenal of weapons to fight vineyard pests from fruit to root. Understanding timing, weather, equipment use and appropriate application of either biochemicals or the release of natural enemies all affect results.

By: Becky Garrison

In What Your Food Ate: How to Heal Our Land and Reclaim Our Health (W.W. Norton & Company), authors David R. Montgomery and Anne Biklé expound on their research into regenerative farming practices that can put carbon back into the ground and improve soil health. This research builds on Montgomery’s introduction to carbon farming that he presented at the 2020 Oregon Wine Symposium. (See the June/July 2020 issue of The Grapevine Magazine).

  Biklé and Montgomery set out to examine the regenerative practices on farms that grow food crops by assessing 10 farms from California to Connecticut that engaged in these practices. When they analyzed how the topsoil from these farms compared to their neighboring farms, they found three broad principles that are central to supporting soil life. The first was the need to minimize the disturbance of the soil. This can translate into no-till or minimal tillage. The second principle is to avoid having bare soil by keeping the ground covered with living plants. Third, grow a diversity of living plant matter.

  Also, they suggested a fourth optional principle: reintegrating animal husbandry. While animals are not necessary for building healthy soils, their presence can serve as an accelerant in speeding up the process.

  In Biklé’s estimation, all of these principles are tailorable. He said, “They’re customizable to a given grower’s setting because what’s going to work in in the Pacific Northwest is going to be different than what’s going on in, say, California or upstate New York.” Hence, it’s key to find a mix of species for a particular cover crop that works on a regional basis. For example, a farm in California that’s subject to ongoing heat and drought would benefit from cover crop species that are particularly resistant to heat waves and do not require much water. Also, a cover crop mix can attract beneficial insects specific to a region that are pest predators or provide other benefits.

  Biklé adds, “If you think of the soil as having a diet it will be different depending on each vineyard’s unique conditions. In other words, the basic principles and practices of maintaining soil health need to be tailored to the soil. Growers can leverage soil health into vine health and a generally more resilient crop, along with minimizing pests and pathogens.”

How to Assess Soil Health

  They recommended assessing the health of one’s soil using the Haney soil test, which was named for USDA scientist Rick Haney. This test includes more than a dozen different soil test values, including standard macro- and micro-nutrients for plant consumption. Compared to other soil tests, the Haney test also estimates nutrients for microbial consumption with a focus on how much nitrogen and carbon are present in the soil.

  This analysis enables growers to ascertain not just the nutrients contained within this soil sample but also how the microbes are making these nutrients available to the soil. If these numbers are low, that’s a strong indication of the need to increase the organic levels through practices like cover crops, leaving residue on the ground or planting high exudate producers (a term that refers to carbon-rich materials).

Results of Applying Regenerative Farming Practices

  They found that, on average, in less than a decade, the topsoil on the regenerative farms in their study had about twice the soil organic matter and a three times higher soil health score than their neighboring farms. Also, when they compared the minerals, vitamins and phytochemical density in the crops they grew, they found that regenerative farms have roughly a 20 percent higher level of phytochemicals, such as carotenoids, phytosterols and polyphenols. Furthermore, they could not find an instance where the regenerative farm performed worse than the conventional farms in the same region. 

  In particular, they noted how regenerative farmers constantly observe what’s transpiring in the field.

Putting These Principles Into Practice

  At this point, they don’t have data demonstrating specifically how these practices work in vineyards. However, their research into how these practices impact food crops points to some positive practices that Biklé and Montgomery hypothesize can be applied to the vineyard. For example, it’s highly suggestive that cover crops planted between the vines will influence both the microbial communities that the plants interact with and the levels of phytochemicals and potential minerals the vines can pull out of the soil and incorporate into their fruit. The end goal is to create an environment where the vine can succeed by relying on its inherent biology.

  Here, Biklé stresses the need to find that sweet spot where there’s just enough stress from physical factors like drought and freeze and biological factors, such as nibbling pests. These stresses cause the plant to churn out phytochemicals. “We know these phytochemicals relate to the flavor and quality of wines, as well as nutritional and health benefits found in wine and other kinds of crops.”

  Too often, Biklé and Montgomery find farmers consider no or minimal till an adequate response to carbon farming practices and do not pursue the other principles for maintaining quality soil. As grapevines aren’t plowed over every year, there’s already some minimal disturbance at play. But growers also need to manage the rows between their vines by planting diverse cover crops. While some growers feel cover crops will compete with their vines, As Montgomery reflects, “If you raise cover crops and then knock them down so they become mulch, these cover crops help keep moisture in the soil more than they respire themselves.” 

  When planting new vines, Biklé recommends doing so with an eye to things like cover crops and animals if a grower is considering those practices. For example, she says to think about the height at which to train the lowest branches to allow enough clearance for cover crops and room for animals like sheep to graze.

  On the topic of inputs, Biklé says, “Occasional use of synthetic chemicals like fertilizers or pesticides probably isn’t a big deal in most cases. But their routine use can affect soil health through interfering with the communication and signaling between a vine host and its root microbiome. As a consequence, root microbiota significantly curtail their normal activities, like stimulating vine phytochemical production and delivering water and must-have nutrients to vines.” 

Challenges in Adopting Regenerative Farming Practices

  In their experience, the biggest difficulty with growers making this switch is their mindset. “If something is working well enough, there’s a reluctance to change,” Biklé opines. Once one can get over this reluctance and adopt an experiential mindset, one can begin to move into the world of carbon farming.

  Other concerns include the need to purchase new equipment. In addition, a given practice might be more labor intensive, which can be a challenge, especially if a region is facing a labor shortage. Also, some may not wish to have sheep in their vineyard based on the assumption these animals would disturb their guests or workers.

  According to Montgomery, a key concern is the need to develop a regional understanding of what would work for vineyards in a given region. He recommends establishing a consortium of local growers who could collectively experiment with what would make for good cover crops between the vines. These growers could set aside a block where they can tinker in their quest to assess the best practices that work in their particular vineyard. In particular, look for any connection between the polyphenol levels of the wine and what’s present in the soil.

  Historically, terroir has been viewed from a winemaking perspective as reflective of the climate, soil and environment. Montgomery and Biklé hope their ongoing research into regenerative farming practices will expand this definition to include an understanding of the soil’s microbial components and how these microbes’ impact both soil health and the quality of the fruit harvested from the vine.