Regenerative Agriculture and the Regenerative Organic Certified (ROC) program

The below-illustrated certification is held by three wineries on the planet: Tablas Creek , Troon Vineyards and Solminer Wine Company. I discuss the long arc to the underlying farming system -- and provide a high-level view of the program -- in this post.

Conventional Agriculture

Conventional agriculture has been instrumental in feeding a growing human population; much more so with the mechanization and synthetic fertilizer advances of the last century. But, as shown in the chart below, this approach had some deleterious effects on the environment and fueled the search for alternatives that began early in the 20th century. The results of these searches are combined in the chart below under the rubric "Organo-Regenerative Farming Practices."

Organic Agriculture

The first movement away from conventional agriculture began in the 1920s in reaction to ecological and soil-related issues (Doring, et al.*):

... acidification of soils, loss of soil structure, soil fatigue, decrease of seed and food quality, and increases in plant and animal diseases were attributed to the chemical-technical intensification of agriculture. In addition, yield levels in Germany decreased drastically in the 1920s in comparison to the years before World War I, even though the use of mineral fertilizers increased.

This early movement toward organic farming focused on improved soil fertility and sustainability while reducing mineral-fertilizer use and producing high-quality crops. 

The United Nation's Food and Agriculture Organization defines organic farming as (Doring, et al.*):

... a holistic production management system which promotes and enhances agroecosystem health, including biodiversity, biological cycles, and soil biological activity. It emphasizes the use of management practices in preference to the use of off-farm inputs ... This is accomplished by using, where possible, agronomic, biological, and mechanical methods, as opposed to using synthetic materials, to fulfill any specific function within the system.

The Rodale Institute defines organic agriculture as:

... a production system that regenerates the health of soils, ecosystems and people wherein, in opposition to the conventional approach, the farmer depends on natural processes, biodiversity and local-condition cycles to provide plant nutrition and fight pests and weeds. 

But the organization does not see the farmer as only being involved with avoidance and substitution tactics; they are also engaged in proactive steps -- crop rotation, composted matter, green manure crops -- to improve soil health.

The table below captures the practices encompassed within organic agriculture.

Table 1. Organic Management Practices

Discipline	Practice	Action	Benefits
Soil Management	Cover crops	Planted between rows	Protects soil from erosion  Add or scavenge nutrients, as desired Alleviate compaction Improve soil structure Helps to smother weeds and control pests and diseases Attract beneficial arthropods Enhance water-holding capacity of the soil Increase biodiversity
	Crop rotation	Different crops differentially on the same plot of land	Improve soil health Optimize nutrients in the soil Combat pest and weed pressures
	Compost	Aerobic combination of traditional waste applied to soil	Reduces weeds and plant disease organisms Provides extra water-holding capacity Promotes the slow release of nitrogen Enhances the plant’s ability to fight off disease
	Organic No-Till	Small-Scale Farmers: hoes and rakes Large Farmers: Roller-Crimper	- Cover crops cut and left on the ground, forms thick mulch that suffocates weeds
Pest Management	Healthy soils	Prevention	Create strong plants that are resistant to pest pressure Encourage populations of natural predators and beneficial insects
	Crop selection	Select pest-resistant varieties of crops
	Pheremones	Disturb pest-mating cycles
	Trapping
	Targeted sprays	Last resort Organic-approved pesticides

Biodynamic Farming

Biodynamic farming, founded in 1924 by Rudolf Steiner, was one of the first movements towards organic agriculture. It is (Doring, et al.) "... a holistic agricultural system based on respect for the spiritual dimension of the living and inorganic environment." 

Biodynamic agriculture is, for the most part, the organic agricultural system with extensions supporting application of specific biodynamic preparations -- said to stimulate soil nutrient cycling, promote crop photosynthetic activity, and transform compost -- along with adherence to the lunar calendar for certain agricultural activities. It should, ideally, be practiced on mixed farms -- including crops and livestock -- to meet Steiner's requirement of the farm as an organism.

Table 2. Main ingredients of the biodynamic preparations 500 to 507 (Source: Doring, et al.)

Preparation #	Designation	Main Ingredient	Use
500	Horn manure	Cow manure	Field spray
501	Horn silica	Finely ground quartz silica	Field spray
502	Yarrow	Yarrow blossoms	Compost
503	Chamomile	Chamomile blossoms	Compost
504	Stinging nettle	Stinging nettle shoots and leaves	Compost
505	Oak bark	Oak bark	Compost
506	Dandelion	Dandelion flowers	Compost
507	Valerian	Valerian flower extract	Compost

Healthy soils and crops are the foundation of biodynamic viticulture. According to adherents, if the microbiome of the soil is not healthy, the vine cannot get what it needs from the soil and can only survive with direct application of nitrogen. This "mainlining of nitrogen" prevents the vine from forming a normal healthy root system. Biodynamic viticulture seeks to "return the microbiome to a healthy balance so that the grapevine can return to its natural process of extracting what it needs from the soil." This makes for a healthier, stronger vine and more flavorful fruit and wine.

In viticulture, organic and biodynamic farming approaches were initially applied in the late-1960s with efforts focused on maintaining crop yields while improving soil fertility and reducing the use of mineral fertilizers. Today 316,000 ha of grapes are grown organically (4.55% of the global grape-growing area), with Europe (266,000 ha) being responsible for the lion's share. Spain, Italy, and France have the largest organic grape-growing areas. Worldwide, 11,200 ha of land are farmed, or are in transition to being farmed, under biodynamic principles.

Certification is available under both the organic and biodynamic farming regimes. There are a number of sustainability certifications but the challenge, according to Tablas Creek's Jason Haas, "is that the word 'sustainable' is not protected and people can claim it without doing much. These standards also have different standards and requirements and often do not set a particularly high bar." Ana Monforte Weitjers, whose business is built around sustainable vineyards, sees the concept as having become "almost a marketing gimmick."

Regenerative Agriculture

Regeneration International defines Regenerative Agriculture as

... a holistic land management practice that leverages the power of photosynthesis in plants to close the carbon cycle and build soil health, crop resilience, and nutrient density.

According to the organization, soil health is improved through practices that increase soil organic matter. These practices:

• Contribute to generating/building soils and soil fertility and health
• Increase water percolation, water retention, and clean and safe water runoff
• Increase biodiversity and ecosystem health and resiliency
• Invert the carbon emissions of our current agriculture to one of remarkably significant carbon sequestration thereby cleansing the atmosphere of legacy levels of carbon dioxide.

Terra Genesis International sees Regenerative Agriculture as a set of farming principles and practices that increases biodiversity, enriches soils, improves watersheds, and enhances ecosystem services. It aims to "capture carbon in soil and aboveground biomass, reversing current global trends of atmospheric accumulation ... at the same time it offers increased yields, resilience to climate instability, and higher health and vitality for farming and ranching communities."

In contrast to the foregoing, the Regenerative Agriculture Initiative relies on "outcomes-based criteria," rather than prescriptive practices, to bound its system. The outcomes that it seeks are Healthy Soils, Healthy Ecosystems, Healthy Communities, and a Healthy Climate.

The practices that comprise Regenerative Agriculture are drawn from a number of parallel disciplines, as shown in the figure below.

Regenerative Organic Certified

The Regenerative Organic Certified (ROC) is a "revolutionary" new certification for food, fiber, and personal care ingredients that has been developed under the auspices of the Regenerative Organic Alliance. Using the USDA Organic certification as a jumping-off point, ROC incorporates elements of Biodynamics and Permaculture into its Land Management corpus and extends beyond that sphere to cover Animal Welfare and Farmer and Worker Fairness. The organizing framework of the program was illustrated in the initial chart in the post.

The program completed its pilot phase in early 2020 (Tablas Creek participated in the pilot). The objectives of the pilot were to (ROA):

1. Develop a greater understanding of how standards can be implemented at the farm and ranch level
2. Provide information that would help to inform the creation of training materials, audit tools, guidance documents, etc.

The program integrates a set of existing standards with ROA protocols to arrive at its finished product. It should be noted that the framework shown at the top of the post is at the highest-possible level of classification; the actual practices extend a number of levels down in terms of detail and specificity. The chart below shows the key differences between the program's three levels.

The chart below shows the mix of the standards that are incorporated into the program as well as a potential timeline for an entity starting the process from ground zero.

Example roadmap
(Source: organicproducenetwork.com)

In commenting on the ROC, Jason Haas noted the following:

An important difference between ROC and the other initiatives is that it is outcomes- rather than process-based. In addition, there are things that ROC addresses that the other soil-based protocols like organic and biodynamic don't because they are focused narrowly.\; things such as resource-use reduction, animal welfare, and farmworker equity. The goal of ROC is to put in place a comprehensive gold standard for farming, from impacts to soils, resources, farm animals, and working communities.

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With this background in place, I will next turn to Tablas Creek's experiences adopting/adapting to the standard.

©Wine -- Mise en abyme

Tablas Creek's Regenerative Organic Certified (ROC) baseline: Organic and biodynamic certifications

Tablas Creek, the pioneer of the California Rhone movement, is the first winery in the world to have simultaneously held organic, biodynamic, and regenerative organic certifications and, to date, is only one of three wineries (the others being Applegate Valley's Troon Vineyards and Santa Barbara County's Solminer Wine Company) to have accomplished this feat. 

Why did the estate pursue a third certification beyond organic and biodynamic and why the Regenerative Organic certification? How difficult a process was it? What were the lessons learned and the benefits derived? I will explore these and other questions in a series of posts beginning with this one wherein I baseline the organization. The sources of information for my posts are interviews conducted with Jason Haas and Jordan Lonborg, Partner and General Manager and Viticulturist, respectively, at Tablas Creek.

Company Origins

Tablas Creek is jointly owned by the Perrin (Chateau du Beaucastel) and Haas (Vineyard Brands) families, a joint venture which came about as a result of a successful search by Robert Haas and the Perrin family for a California site which would be suitable for the planting of Rhone varieties. The company was launched in 1989 with the purchase of a 120-acre parcel in the Adelaida District, just west of Paso Robles. The area's climate was similar to that of the Rhone and the shallow rocky limestone soils were the same geologic origin as was the soils at Beaucastel. Average elevation was 1500 feet.

The intent of the estate was to produce wines at Tablas Creek that were similar to those produced at Chateau du Beaucastel; hence the painstaking search for similar growing conditions. Once the location was secured, Rhone vinefera, and a variety of rootstocks, were imported from the Chateau. Planting began in 1994 and, as of 2020, 115 acres had been planted to vine.

Viticulture

The estate's viticulture practices emphasize quality through dry farming and moderate crop levels. The estate gained organic certification in 2003, biodynamic certification in 2017, and Regenerative Organic Certification in 2020. The first two are discussed further herein with the third, and its transition, discussed under separate cover.

Organic Farming

Tablas Creek was always going to be farmed organically because that was the practice in use at Beaucastel where it was held that the only way to be true to terroir was to farm organically. Neil Collins, the Tablas Creek's Executive Winemaker and Vineyard Manager, had spent time training at Beaucastel and had brought organic farming to the fledgling estate upon his return.

The estate's organic practices include:

• No chemical herbicides, pesticides, or fertilizers used in the vineyards
• The use of cover crops in order to minimize erosion and to host beneficial insects
• Composting in order to return nitrogen to the soil
• Compost tea to control mildew in the vineyard and to reduce the need for sulfur.

Organic farming allows for conservation tillage (ridge, mulch, or strip). According to Jordan, Tablas Creek tills its dry-farmed blocks.

Tillage in dry-farmed blocks is crucial due to the high clay content in our soil. Without some sort of soil disruption (as the soils dry out after the winter rains) large, deep cracks form, allowing precious moisture to evaporate into the atmosphere. We create what is known as a dust mulch layer by breaking up the top 3 to 4 inches of soil into finer particle sizes thus preventing any form of shrinking.

Farming organically provided an "ecosystem that was clean and balanced." But Tablas Creek wanted to do more within that framework so they began to look around for optimization opportunities. This led to initiatives to reduce external inputs. An example of this is the estate using material already on the farm to make its own compost rather than buying compost offsite and having it trucked in. This particular action reduced the carbon expended in fertilizer acquisition.

Biodynamic Farming

Tablas Creek began biodynamic farming experiments on a 20-acre plot in 2010. Jason said that the tasting team noticed that the wine from that plot came to the fore when tasted with its peers. They expanded the trial to 40 acres in subsequent vintages and the wines from these grapes proved to be "super expressive" and the associated soils were "healthy and vibrant." The entire vineyard was converted to biodynamic farming in 2016 and certification was awarded in 2017. Some of the programs implemented during the biodynamic regime are discussed below.

Sheep

Running sheep through the vineyard has a number of significant advantages:

• Efficient weed removal without the compaction that comes with spraying
• Tons of manure/acre/day on every inch of ground between the vines. Phenomenal amount of nutrients added to the soil annually
• The sheep can clear out the understory of the forest thus acting in a fire suppression role.

Pursuit of a Diverse Ecosystem

This is manifested in a number of ways, with especial focus on moving away from a monoculture. The use of sheep in the vineyard is a move in that direction but so are initiatives such as: planting fruit trees (apples, pears, plums, peaches, nectarines, quince, pomegranates, figs, cherries, and persimmons); a vegetable garden (fresh tomatoes, corn, zucchini, squash, melons, radishes, and basil); retaining sections of native vegetation and planting insect-friendly flowering plants; building owl boxes to control rodent pests naturally; and keeping their own bee hives.

As regards trees on the estate, Jordan states (in a follow-up email);

As far as fruit trees are concerned, we have one orchard made up of Pome fruits (apples, peras and quince), cherries, and figs. There are about 10 acres of olive trees planted as windbreaks lining roads throughout the property. Lastly, throughout our dry-farmed plantings, we typically plant one fruit tree for every 50 vines or so. In the unfortunate case of vine death in dry-farmed locations, we plant fruit trees instead of planting another vine.

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This then, was the state of affairs when Tablas Creek was approached to participate in a Regenerative Organic Certification pilot program. Before getting into the particulars of the program, I will, in my next post, cover the basic elements of Regenerative Agriculture and the Regenerative Organic Certification.

©Wine -- Mise en abyme

The business end of the Grapekeeper rent-a-vine program

Grapekeeper is a multi-faceted, sustainably oriented, luxury rent-a-vine program that is the brainchild of Portuguese Environmental Engineer and Entrepreneur (and Winelover) Ana Monforte Weijters. After its initial launch in 2018, the company rebooted in 2019 guided by the business model illustrated below. 

Entry requirements for producers are (i) sustainability and (ii) quality. Ana mourned the fact that sustainability had almost become a marketing gimmick; it is fundamental to her business. She defines it as: "the capacity to endure in a relatively ongoing way across various domains of life. To use resources without depletion or, even better, with regeneration, to produce experiences as products that enrich the consumer as well as the other contributors in the production chain."

Grapekeeper offers customers the ability to rent vineyards in one of three sizes from a current list of seven producers drawn from Germany, Italy, Spain, France, and Portugal (see Table 1 below). The customer can invest in one of three size classes with an estimated number of bottles promised at each level. The estimated number of bottles for a given plot size will vary from producer to producer based on vineyard yields. The level one offering promises an estimated number of bottles plus a number of benefits while levels two and three includes all of the activities of the preceding levels plus a higher number of bottles coincident with the increased plot sizes.

Table 1. Producers profiled on the Grapekeeper website.

Partner	Location	Cultivar(s)	Wine Style	Offerings
Stafelter Hof	Mosel	Organically farmed Riesling	Still white	150 - 450 sq m; 600 - 900 sq m; 1050 - 1350 sq m
Selva Capuzza	Lake Garda	Turbiana	Still white	100 - 300 sq m; 400 - 700 sq m; 1050 - 1350 sq m
Vinyes del Terrer	Tarragona	Garnacha Tinta, Cabernet Sauvignon	Still red (85% Garnacha Tinta)	200 - 800 sq m; 1000 - 1600 sq m; 1800 - 2000 sq m
Vega Aixlà	Montsant	Organically farmed Tempranillo	Still red	200 - 800 sq m; 1000 - 1600 sq m; 1800 - 2000 sq m
Rivetto	Piedmont	Barbera	Still red	100 - 300 sq m; 400 - 600 sq m; 700 - 1000 sq m
Serveaux Fils	Champagne	Pinot Meunier	Champagne	100 - 300 sq m; 400 - 600 sq m; 700 - 1200 sq m
Vinha do Carrel	Douro	40+; 80 - 100-year-old vines	Field-blend still red	300 - 400 sq m;500 - 700 sq m; 800 - 1000 sq m

The customer is always invited to visit the vineyard to discuss sustainability and its influence on, among other things, wine quality, regional sustainability, and the communities that are dependent on wine production for their sustenance. There is also a fun aspect to the program as the customer can bring family and friends along to aid in the harvesting of his/her plot. Ana has indicated that a number of new producers will be added to the fold over the course of the next three months.

Ana defines Grapekeeper success as:

• Getting wines to clients
• Financial health
• Seeing the people around her happy.

The key, she said, is health: health of the people, health of the ecosystem, and health of the business. For her, people are the most important part of this venture.

Ana Monforte Weijters
(Courtesy Grapekeeper)

As far as the future is concerned, she wants to be more inclusive and to continue to grow the business. She sees a lot of potential for client growth as well as geographical expansion of the producer cohort. She also sees opportunities to build a raft of communities as both the producer and client groups grow; but that is down the road a bit.

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What are the future prospects for the business? Jamie Goode is complimentary when he notes that Ana has teamed up "with some serious wine producers." One of the keys to the venture's success will be its rate of customer acquisition and development of a more durable marketing strategy to fuel that growth. Today customer marketing is primarily word-of-mouth; that is not a strategy with legs.

Ana has been critical to the company's success to date and will continue to be so in the future. She possesses a number of qualities that will stand her -- and the business -- in good stead going forward:

• She is a visionary but is also able to effectively communicate that vision to enlist prospects and to operationalize the concepts as key elements in a going concern
• She is highly motivated and extremely hard-working. It seems that every time I communicate with her she is either driving or flying to or from a producer meeting. One thing that she has the be careful of is not being seduced by the sexiness of producer visits to the detriment of customer-acquisition efforts
• She is thoughtful, yet approachable, and is well-versed in issues relating to sustainability and regenerative agriculture
• She is empowered, driven, fearless, and in possession of an entrepreneurial spirit but is also warm-hearted, unselfish, and willing to pitch in to help.

Grapekeeper is in good hands.

©Wine -- Mise en abyme

The conception and design of Grapekeeper, the Champagne of rent-a-vine programs

The closest most winelovers will get to owning a vineyard is at the point of purchase of a bottle of wine. That is insufficient for some wine drinkers of means; so they go out and buy a vineyard and get the relevant assistance for wine production. Then there are the in-betweeners: they have the passion but not the means/interest to pursue full-time ownership. For this segment of the wine-loving community, renting a (portion of a) vineyard fits the bill. And there are a number of solutions set up to meet this need but they tend to be very specific.

Not so Grapekeeper, the multi-faceted, luxury, sustainably oriented, rent-a-vine program that is the brainchild of Portuguese Environmental Engineer and Entrepreuner (and Winelover) Ana Monforte Weijters. I will be describing the fundamentals of this program over two posts beginning herein with its conception and initial development. I have become familiar with Grapekeeper through my travels with Ana in Portugal as part of the #Winelover Community, through joint work on #Winelover Committee projects, as a subject of two InstagramLive interviews on Regenerative Agriculture, through two Grapekeeper-specific interviews, through many Messenger and email exchanges, and through secondary research.

Ana Monforte Weijters (Courtesy Grapekeeper)

Ana describes herself as Founder, Chief of all Troubles, and Managing Director of Grapekeeper. She grew up in the Portuguese countryside in a small town called Maia. She made wine with her grandfather and remembers these as exhilarating times filled with smells, people, and memories (especially around harvest).

Ana left Maia and continued her studies in Porto where she graduated with a degree in Environmental Engineering. Her work experience includes stints in Antwerp and Africa where she consulted on waste management, sustainability, biodiversity, and climate-effects mitigation.

She was resident in the Netherlands between 2007 and 2010 and again between 2015 and 2021, the early part of the latter period being co-incident with a burgeoning interest in wine. In this timeframe she studied the WSET approach and begun visiting vineyards. As her vineyard visits grew in number, Ana began to think of winemakers as "keepers of the land." She postulated that quality differences between wines reflected the differences in the way that winemakers managed the land.

Ana's first harvest was in Mosel in 2017 after which she went on to Piedmont. After a week of touring and talking to farmers, the first wisps of the Grapekeeper concept began to waft through her consciousness. That initial conception was a melding of:

• Fantastic producers with vision, personality, and terroir
• Sustainable farming of specific plots
• Consumers who had the ability to shift things because of their purchasing power (Ana sees these as people who are open to/practice sustainable, conscious, holistic buying and consumption and who perceive "that a luxury must be luxurious throughout all its value chain and touch, in a positive way, everyone and everything involved in its making.").

With this framework in mind, Ana began the legwork of developing an understanding of the market, market players, and existing business models. Once she had fleshed out her knowledge base, she launched an initial offering in 2018 -- with a business partner -- centered on vineyards in Germany and Italy. This was already an innovative offering in that (i) it had sustainability at its core and (ii) it offered potential customers a choice of vineyards/wine styles/wine types derived from two countries. They "did a lot of tweaking" of the offering and business model in that initial year.

The partnership did not pan out (Ana prefers not to dwell on the why nots) so she re-launched as the sole owner in 2019. The business was given a boost by her June entry into a Netherlands business competition sponsored by Quote Magazine. The competition, and the associated magazine and media coverage, “sped up the process" by providing her (i) the time and space within which to examine the business and develop a sound implementation plan and (ii) the opportunity to meet potential producer partners (Niepoort, in the Douro, for example).

By the end of 1919 she had developed a robust business model. had established a set of strict criteria for Program producers, determined an initial customer-acquisition strategy, and defined her role within the model. And then the pandemic hit, slowing everything down to a crawl. But it also provided her the time to refine the offering and the business model. I will cover the current offerings and business model in a subsequent post.

©Wine -- Mise en abyme

Chinon AOC and the wines of Olga Raffault

The region that is currently called Chinon AOC has been producing grapes and wines for hundreds of years and was rewarded with an AOC designation in 1937. The Olga Raffault family has been making quality wines in this region for over five generations but I was only recently introduced to their offerings. I explore the region, the estate, and its wines in this post.

Chinon AOC

The Chinon AOC covers 18 communes on both sides of the Vienne River prior to its merger with the Loire. There are approximately 1,821 ha of Cabernet Franc vines in the region and, in general, the wines from the area are fresh and supple with flavors and aromas of red fruits and violets. Three different terroirs have been identified  and the wine styles vary based on their terroir of origin. The slopes and hills along the Vienne River are composed of a Late-Cretaceous limestone called Tuffeau and the wines from this soil have great structure and aging capability.  The area around the commune of Veron is characterized by a Late-Cretaceous clay and produces wines that are intermediate to the lighter Chinons produced in the alluvial sand and gravel soils that can be found in communes such as Panzoult.  Chinon wines are barrel-aged but the neutral barrels impart no oak flavors to the wine thus allowing the natural character of the grape to advance unimpeded to the bottle.

Olga Raffault

Olga Raffault is located in Veron commune of Chinon but farms 24 ha across the region: 23 ha of Cabernet Franc and 1 ha of Chenin Blanc. Estate vines average 30 years of age and are distributed over the three Chinon terroirs. The location of the owned vineyards are illustrated in the chart below while the wines, and their construction, follow immediately after.

Sources and composition of Olga Raffualt wines

I recently tasted three of the Raffault wines: the 2018 Chinon Blanc Champs-Chenin; the 2018 Olga Raffault Chinon Les Peuilles; and the 2016 Olga Raffault Chinon Les Picasses.

The Chinon Blanc Champs-Chenin showed intense white fruit on the nose along with sage, herbs, and spice. Complex and layered. Brisk acidity on the palate. Citrus and citrus rind accompanying a rust-like minerality. Drying on the palate. Lengthy finish. 

Rich, red fruit on the nose for the 2018 Les Peuilles, along with forest floor, gunflint, and a smokiness. Ripe red fruit on the palate. Concentrated. Full round mouthfeel. Late arriving tannins and salinity. Lengthy, coating finish.

The 2016 Les Picasses had a perfumed nose with bright red fruit, spice, minerality, licorice, saltwater taffy and wet cigarette. On the palate, a red fruit core and smooth tannins. Complex and balanced. Long, lean finish.

These three wines were of exceptional quality with the reds approachable but with the peaks 5 to 10 years out. The QPR here is awesome.

©Wine -- Mise en abyme

Trees in the vineyard (Agroforestry) and the effect on grapevine root systems

Agroforestry is one of the key soil health and land management practices of the Regenerative Organic Certification. The practice, as defined by the US Department of Agriculture (USDA), involves "the intentional integration of trees and shrubs into crop and animal farming." Trees provide a number of below- and above-ground services which may be of benefit to the viticulturist (documented by Favor). I have previously reported on the impact of trees on vineyard water parameters and soil-based nutrients. I continue herein with an examination of the effect of trees on vine root systems. Portions of this post draws heavily on the research reported out in Favor's work.

Soil Structure

The vineyard site is a key variable in the production of high-quality grapes, which is, itself, a key requirement for the production of high-quality wine. According to Wolf and Boyer (Vineyard Site Selection, Virginia Cooperative Extension), the best vineyard soils "permit deep and spreading root growth" and provide a moderate supply of water year-round. Katherine Favor posits that "much of the ability of vines to absorb both water and nutrients in the face of competition depends on the health and spatial distribution of the vine's root system" with research suggesting that "the depth and expansion of grapevine roots is highly dependent on soil structure and permeability ... and that grapevine root plasticity is also influenced by planting density and competition." 

What are the soil characteristics that will permit "deep and spreading root growth" and year-round access to water?  The most important requirements are internal water drainage and water-holding capacity. Geologic permeability (the capability of a porous rock or sediment to permit the flow of fluids through its pore spaces -- Dictionary.com) is seen by Wolf and Boyer as perhaps the most important consideration in a candidate vineyard's soil. Mark Chien (Soil and Site Selection Considerations for Wine Grape Vineyards, Pennsylvania State University) sees well-drained soils as a common denominator among all great vineyard sites. These soils "strike a balance between adequate depth and drainage and water-holding capacity" and vines deployed therein will have adequate water access during the summer and can rapidly drain water from the soils in the event of rainfall during the grape-ripening period. According to Favor, soil porosity is an even more important determinant of grape quality than is nutrient availability.

Another key soil feature is effective rooting depth. According to UCDavis, about 60% of the root structure of a vine plant can be found in the first two feet of the surface but individual roots can grow as deep as 20 feet, depending on soil permeability, the level of the water table, and the rootstock variety.

According to Favor, the above characteristics, among others, are influenced by soil structure. Soil structure -- the spatial arrangement of individual soil particles, their aggregates, and the pore space between them -- "affects soil strength, water holding capacity, nutrient retention, aeration, friability, erodibility, plant root movement and biological activity." A high-quality soil structure allows for deeper and stronger vine root systems and higher grape production quality. Soil quality characteristics are summarized in the chart below.

Agroforestry's Impact on Soil Structure

Agroforestry has been shown to improve soil structure through a variety of mechanisms (Favor):

• A mulching effect from litterfall and pruning materials can have beneficial effects on topsoil structure
• Soil cover improves soil structure by reducing raindrop and irrigation effect → conserved surface macroporosity → greater water infiltration rates → improved soil penetration
• High amounts of root biomass produced by the trees
• Tree roots improve soil macroporosity by breaking up compacted soils and leaving behind old root channels that grapevine roots are able to occupy for greater rooting depth capability
• Finer roots contribute to improved soil structure
• Tree buffer treatments produced higher porosity, increased mesoporosity, and improved soil structure
• Increased organic matter (OM) content
• Soil structure is largely influenced by the amount of OM in the soil
• Higher levels of OM → higher aggregate stability and overall improved structure
• Higher levels of OM contribute to increasing water infiltration and fertility
• Organic matter is able to use "sticky substances" to glue soil particles together → stable soil pores.

In summary, the agroforestry-related increase in OM → increased soil structure → increased rooting capability → higher yields and higher quality fruit production (Favor).

Competition Between Tree and Grapevine Roots

According to Favor, "much of the ability of vines to absorb both water and nutrients in the face of competition depends on the health and spatial distribution of the vines' root system." 

Research has shown an overlap in the activity spheres of plants and vines: 63% of grapevine roots are in the upper 60 cm of soil compared to 77% of conifer roots while 80% of grapevine roots are in the upper 1 m of soil compared to 91% for trees. Grapevines might have a deeper concentration of roots at deeper soil profiles as their remaining roots extend to depths of as much as 12 m. Grapevine roots can spread out up to 10 m laterally from the trunk.

The most frequent agroforesty applications to date are olive trees with grapevines. Olive trees have similar lateral-root experiences as does the grapevine but its vertical roots grow even deeper. Similar to the grapevine, olive trees absorb the majority of nutrients in the top 1 m of soil and water in the top 1.2 - 1.7 m of soil. As Favor concludes, there may be substantial below-ground overlap between these systems.

Competition notwithstanding, Favor concludes that:

The positive effects that trees impart on soil structure, soil quality and root plasticity allow for deeper and stronger root systems that can better absorb nutrients and water despite competition from trees ... Fracture lines left behind by tree roots allow opportunities for grapevines to grow even deeper than they otherwise would have ... Additionally, competition from tree roots can trigger grapevine root plasticity, which results in increased root length density and increased nutrient and water absorption capacity per cm of soil. Tree roots and grapevine roots are indeed able to adapt to competition and thrive despite occupying overlapping niches.

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This concludes our examination of the below-ground services provided by trees in an agroforestry system. As per Favor, "there is growing evidence that incorporating trees into vineyards could play a valuable role in the future of viticulture in the coming years."

I will next turn to examination of the above-ground services provided by trees in an agroforestry system.

©Wine -- Mise en abyme