Regenerative Agriculture and Agroforestry: The effect of trees on water parameters in the vineyard

Drawing heavily on Favor's Master Thesis, my recent post on Agroforestry practices in Regenerative Agriculture identified the range of above- and below-ground services provided by trees in the context of vineyards. I return to the topic to discuss the workings of those particular services and their detailed impacts. 

The chart below summarizes the above- and below-ground services, with the below-ground component revolving around elements associated with water, nutrition, and grapevine rooting patterns. I treat the water aspect in this post.

Water is extremely important to the functioning of the vine plant but too much, or too little, can have adverse effects, with run-on impacts on fruit quality. Water sources for the vine include stored soilwater, effective in-season rainfall, and any water that is added by the viticulturist. According to Favor, the presence of trees in the vineyard will result in (i) increased water conservation and (ii) competition between trees and grapevines for water.

Increased Water Conservation

Favor points out that even though grapevines are a relatively drought-resistant species -- most wine regions are located in relatively low-rainfall areas -- "conserving moisture is a high priority in most vineyards." While it would be difficult for droughts to kill off the vines entirely, they can:

• stunt vegetative growth
• reduce fruit quality
• completely suppress fruit production
• yield expensive water bills in the cases where irrigation is practiced
• dry up the groundwater.

Trees in agroforestry systems conserve moisture using the mechanisms illustrated in the chart below.

Further, trees increase soil water-holding capacity by improving overall soil structure (Favor). The figure below shows the components included in a soil matrix. According to Favor, trees 

Soil matrix cross-section (Source: serc.carletoon.edu)

improve the soil structure by boosting both organic matter and microbial populations which, in turn, aid in the formation of stable aggregates and a higher incidence of micropores and macropores. These micropores and macropores are the storehouses in which the increased levels of water are held. According to Favor, agroforestry systems can increase organic matter by up to 100% with every 1% increase, yielding a 1.9% increase in soil water-holding capacity.

"All in all, agroforestry systems are able to significantly increase soil moisture, water infiltration rates, water recharge capacity, and water holding capacity" resulting in "greater drought resistance and less reliance on irrigation" (Favor).

Competition between Trees and Grapevines for Water

Favor asserts that some competition for water between trees and grapevines in an agroforestry system is inevitable. The trick here is to avoid severe water deficits for the grapevine (see table below).

Effects of Severe Water Stress on the Grape Vine

Stage	Effects
Bud Break	Water stress infrequent at this stage Moderate levels -- uneven bud break and stunted shoot growth Severe levels -- poor flower cluster development; reduced pistil and pollen viability; nutrient deficiencies
Post-Berry Set	Severe levels -- flower abortion and cluster abscission; reduced canopy development; impact on following season’s crop potential
Post-Fruit Set	Restrict berry cell division and enlargement resulting in smaller fruit and lower yields Reduced shoot development Reduced yield potential Reduced fruit soluble-solids accumulation Higher pH fruit Decreased acidity Reduced color development in red varieties
Post-Harvest	Reduced root growth with resulting decreased nutrient uptake and micronutrient deficiencies the following spring

Source: Wample and Smithyman, Regulated deficit irrigation as a water management strategy in vitis vinifera production in Deficit Irrigation Practices, ftp://ftp.fao.org/agl/aglw/docs/wr22e.pdf%20.

Overlapping somewhat with the above, Favor sees excessive water stress:

• reducing the number of bunches per vine
• reducing photosynthesis (reduced leaf area and increased stomatol closure yield lower berry sugar levels)
• reducing both fruit and vegetative growth
• negatively affecting sugar metabolism and flavor development.

Excessive water stress, then, is to be avoided at all costs. Some water stress, on the other hand, does seem to have positive quality implications for the grapevine.

Vine water stress is created when this available water supply is reduced beyond the vines climatic needs.  In areas where irrigation is allowed, viticulturists use controlled irrigation to induce vine water stress. In this scenario, the soil water resources are utilized for the plants needs up through bud break and then amounts less than required are provided to the plant (This would include effective rainfall plus irrigation). This limited water access creates a stress situation for the vine, which, in turn, results in the quality enhancements that the viticulturist seeks. That is, the soil will provide for the vine's needs with stored soil water and the vines will dive deeper -- a stressed situation -- in search of additional water when the near-in sources have been depleted. 

Research carried out by UCDavis' Dr Terry Prichard on berry size and vine balance shows that:

• For a given berry size, vines grown with low irrigation have a higher anthocyanin concentration (between 15% and 33%) than those grown under higher irrigation conditions
• There is a higher concentration of skin tannins in low- versus high-irrigation environments
• Water deficits result in lower yields which, in turn, results in lower veggie characteristics and fruitier wines.

According to Favor, mild water stress has been shown to:

• Improve wine quality by increasing the sugar:acid ratio, lowering malate and total titratable acid concentrations, and increasing total soluble solids
• Increase grape phenological profiles
• Increase sugar concentration in berries
• In a study comparing the effects of 25%, 50%, 70%, and 90% soil moisture regimes, the 25% regime was found to produce the smallest berries and the highest concentrations of sugars and phenological compounds.

Trees and grapevines do impart some levels of water stress through "competition and root niche overlap" but this is more than offset by the beneficial water contributions provided by trees (as detailed in the foregoing section). Some stress is good for the vine plant; and trees in an agroforestry system will provide that. According to Favor, "given all the tradeoffs, research findings suggest that trees would not induce damagingly high levels of water stress."

I will continue in my next post with agroforestry's impact on vine nutrition parameters.

©Wine -- Mise en abyme

Piccolo Derthona: A Colli Tortonesi Timorasso entry point for the impatient

Timorasso is a notoriously difficult grape to grow. And your troubles are not over once you get it into the cellar: it requires extended vessel and bottle aging before it is truly ready to be released on the market. Making Timorasso wine is expensive when you factor in the additional vineyard labor costs and the time, material, and opportunity costs associated with extended aging. Producers wanted a mechanism whereby they could realize some offsetting revenue while they awaited the release of the Derthona and thus was born the concept of the Piccolo Derthona, an earlier-release, lower-cost, 100% Timorasso wine.

I have previously characterized the Piccolo Derthona as being akin to a Rosso di Montalcino but recently came across a more pointed reference: "The name, Piccolo Derthona, is inspired by what is done in French Chablis, a great territory for white wines, where the Petit Chablis is produced with the same goal, that of creating a distinctly fresh and pleasant wine, compared to the richer and more structured Chablis, in our case the Derthona."

The Colli Tortonesi Consorzio has submitted an application to the appropriate authorities for the designation of a Derthona sub-appellation within the Colli Tortonesi DOC covering the production of Timorasso vines within its borders. The submittal covers a Riserva (released a minimum of 2.5 years after harvest), a Derthona, and a Piccolo Derthona (both requiring a minimum of 1 year aging). The difference between a Derthona and a Piccolo Derthona will be based on quality parameters as well as tasting panel assessments.

The picture below show the eight Piccolo Derthonas currently produced from Colli Tortonesi Timorasso grapes. 

Piccolo Derthona wines currently produced in
Colli Tortonesi (Picture courtesy of Conrad Mattern)

The producers currently utilize a mix of reduced aging time (Pomodolce, Boveri Giacomo, Massa, Cantina di Tortona), lower quality/younger grapes (Repetto), or both (Canavero Luca) to distinguish the Piccolo Derthona from the Derthona. The proposed Derthona appellation calls for a similar aging period for both Piccolo Derthona and Derthona so producers will either have to declassify grapes, use grapes from younger vines, or use grapes from lower-quality production sites for the Piccolo wine. 

It should be noted that extending the aging period of Piccolo to one year will increase its aging costs and will also cut out an early revenue source for producers who had historically aged the wine for less than one year. 

It should be noted that only one of the big-name producers - La Spinetta -- currently offers a Piccolo Derthona and that none of the non-Langhe outsiders do. It will be interesting to see whether this state of affairs continues into the future. 

I personally have been concerned that a wine drinker encountering Piccolo as her/his intro to Timorasso may wonder what the fuss is all about and not take the time to explore the variety further. 

Below I describe the individual offerings in some more detail.

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Pomodolce Piccolo Derthona

Pomodolce farms 3 or 4 ha (depending on source) in the Montemarrone municipality of Val Curone. The estate, established in 2005, sources its estate grapes from the areas of Fontanino, Pomodolce, and Barone. The vineyards -- average elevation 380 m -- are sited on calcareous clayey soils and are exposed to the southwest. Vines are planted at 3500 vines/ha and are farmed using organic principles.

The grapes are fermented in stainless steel tanks and aged in-place for 8 months. In contrast, the estate's two Derthona wines are each agaed for 10 months.

Boveri Giacomo Piccolo Derthona

The grapes for this wine are sourced from a Costa Vescovato plot which has been farmed by the family for decades but which has been planted to Timorasso beginning in 2013. Vines are trained Guyot with the between-row spaces grassed.

The grapes are hand-harvested and then soft-pressed with the must clarified prior to fermentation. The wine remains on the lees for 5 - 6 months and is then bottled in the spring following harvest.

Canevaro Luca Piccolo Derthona

This 8- (or 9-) ha estate is located in the municipality of Avolasca at elevations ranging between 300 and 350 m. The vines are farmed organically with grapes for the Piccolo Derthona sourced from younger vines (A total of 1.5 ha is dedicated to Timorasso vines).

The grapes are hand-harvested and soft-pressed prior to fermentation in stainless steel tanks. The wines are aged for 5 months on the lees, with batonnage, and are filtered prior to bottling.

Vigneti Repetto Piccolo Derthona

The Piccolo Derthona is a new wine for the estate. Gian Paolo has described his Piccolo Derthona as "an entry-level wine made from young vines and/or lower quality grapes. This wine has less structure, less body, and a lower price point than the (estate's) Derthona. It exhibits freshness and is suitable for a wine bar."

I tasted the 2019 version of the wine and found saline green olive, a hint of sweet white fruit, and spice on the nose. It was very broad on the palate (wide open, I would say) with underripe citrus fruit and hints of salinity. No hint of the structure that is notable for this variety. The heat on the chest stands in contrast to the 12.5% stated alcohol on the label. Mid-weight, with average length.

Vigneti Massa Piccolo Derthona

The grapes for the Massa Piccolo Derthona are sourced from the Boscogrosso and Sigala vineyards. The production regime for Massa wines are, in general, as follows:

• Hand-harvesting
• Maceration on the skins in concrete vessels for 48 to 60 hours without sulfuring
• Soft pressing
• Fermentation with indigenous yeasts in stainless steel tanks (20 - 25ºC)
• Spontaneous malolactic fermentation after temperature reduced to 10 - 18ºC
• Wine aged in stainless steel tanks for one year (with batonnage)
• Light filtration prior to bottling
• Minimum 6 months bottle aging.

I tasted the 2018 Piccolo Derthona. Stone fruit, sea spray, minerality, spice, menthol, and a hint of burnt orange on the nose. Much more powerful on the palate than is the case for the the La Spinetta. Lime and lime skin, green tamarind, minerality, salinity, and lip-smacking tannins. Drying finish.

On the day following, sweet white fruit, tempered by a grey slatiness, pea soup, menthol, and spice. Weighty, bracing lime on the palate along with salinity, spice, and a leaden minerality. Bright. Lively. Lengthy finish.

Cantina di Tortona Piccolo Derthona

Grapes for this wine are sourced from Avolasca, Vigguzolo, and Vho where they are grown at elevations ranging between 250 and 450 m in clay and sandy soils with south and southwest orientations.

The grapes are subjected to a 6-hour maceration in an inert environment prior to alcoholic fermentation. The wine is aged for 6 months in continuously suspended fine lees.

Terralba Piccolo Derthona

No information on this wine was available from traditional sources. Conrad Mattern reached out to the proprietor but he had not yet responded at press time.

La Spinetta Piccolo Derthona

La Spinetta purchased 5 ha of land distributed between Montegiocco, Monleale, and Montemarzino for its entry into Colli Tortonesi Timorasso production. The soils are calcareous and clay at elevations ranging between 350 and 400 m and with southeast and southwest exposures.

The grapes are hand-harvested and fermented naturally in stainless steel tanks. La Spinetta's wine ages for 8 months on the lees after which it is filtered and bottled. The wine spends another 3 months in bottle before its release on the market. 

The 2019 Piccolo Derthona was La Spinetta's inaugural Timorasso vintage.  Neither the nose or palate yelled "Tortonesi Timorasso." This Piccolo was relatively thin.

©Wine -- Mise en abyme

Regenerative Agriculture: Agroforestry for improved soil health and as a foil against climate change

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." Agroforestry (a term coined in the 1970s) "seeks positive interactions between its components, aiming to achieve a more ecologically diverse and socially productive output from the land than is possible through conventional agriculture" and "is a  practical and low-cost means of implementing many forms of integrated land management." (Brittanica).

According to rainwater runoff.com,

Although the story varies greatly from one place to another, the practice of maintaining or integrating trees in the agricultural landscape has existed from ancient times around the world and has constituted the default practice in terms of land use management. It was only during the last centuries that farming and trees became disassociated as monocropping became more common, in an effort to intensify food production.

Brittanica cites written records of agroforesty dating back to Roman times while my research shows the incorporation of trees into the Chianti Classico vineyards in the 14th century with a 20th-century switch to low-trained vines and monocropping accompanying the failure of the mezzadria system.

The USDA has categorized agroforestry systems as shown below.

What is the direct application of agroforestry to viticulture? The image below illustrates an alley-cropping application in a vineyard.

Alley cropping (Source: yaleclimateconnections.org)

On the basis of a comprehensive literature review in her 2021 Master's Thesis, Katherine Favor stipulates that "Agroforestry can benefit vineyards in many ways, both in terms of the above- and below-ground services that it provides to vineyard ecosystems. Agroforestry has been shown to affect below-ground parameters in vineyards positively by increasing drought resistance, reducing erosion, building organic matter, bettering soil structure, and improving vine rooting capability" and above-ground parameters by "... reducing pest and disease pressure, preventing wind damage and erosion, increasing stomatal aperture and leaf area, protecting against heat stress, and protecting against frost."

Summarizing the findings of her research on agroforestry below-ground services, Favor states:

Existing studies reveal that the presence of trees in vineyards imparts a neutral to positive effect on parameters surrounding grapevine water status and water stress despite competition, due to trees’ ability to reduce evaporation and transpiration, modify the microclimate, and distribute water through hydraulic lift. Studies show that trees likely have a slight negative effect on grapevine nutrient status within 4 m of trees; however, trees also have been proven to significantly improve vineyard soil quality. Trees may also potentially increase vine rooting depth and density by improving soil structure and inducing root plasticity. Overall, the positive below-ground services that trees provide in vineyards, paired with the ecological and cost-saving benefits that trees impart to a viticultural ecosystem as a whole, might very well balance out these negative effects.

The above-ground services revolve around pest and disease, altering light patterns and vineyard microclimate.  In the area of pest and disease management, Favor finds:

The existing research on integrated pest management in vineyard agroforestry systems demonstrates the effectiveness of utilizing agroforestry to create heterogeneous vineyard landscape designs as a way to combat pests and diseases. Monocultural vineyard designs are associated with numerous pest management issues that leave vineyards vulnerable to losses, dependent on pesticides, and economically less-resilient. Creating diverse vineyard agroforestry systems by incorporating trees into vineyards has been shown to benefit insect pest management efforts by providing habitat for natural enemy insects and vertebrates, which results in increased abundance of natural enemies, increased parasitism rates, reduced insect pest pressure, and subsequently, reduced yield losses. Although vineyard agroforestry systems can cause increases in pest insect abundance as well, the existing literature shows that the accompanied increases of natural enemy populations result in overall increased insect pest control and reduced herbivore damage. Vineyard agroforestry systems may also control bacterial and viral infections by controlling the insect vectors that transmit these pathogens, however, great care must be taken to avoid intercropping grapevines with trees that could be hosts for harmful viral and bacterial vectors. The prevalence of fungal infections in vineyard agroforestry systems may be increased by the increased shade that trees impart, but may be reduced by trees’ windbreak effects and by the beneficial reductions 52 in vine vigor that occur as a result of below-ground competition between trees and vines. The presence of trees in vineyards also facilitates the proper timing of precision pesticide applications by slowing wind and creating conditions conducive to pesticide application at the precise moment when pest pressure is at the proper threshold.

For light patterns:

The presence of trees in vineyard agroforestry systems impacts light patterns, which, in turn, affect wine grape physiological, production, and quality parameters in both positive and negative ways. Trees reduce the quality and quantity of light that reaches understory crops, trees reflect light from their canopies onto understory crops, and tree shade reduces temperature ... In wine growing regions impacted by high temperatures and more frequent heat waves, shade from trees may benefit grapevines by reducing sunburn from UV radiation, maintaining photosynthesis rates, preventing yield losses from shriveling, maintaining adequate sugar levels, preventing acid degradation, allowing anthocyanin development, and promoting synchronized development of flavor profiles for an overall balanced and high-quality wine. In wine growing regions that are less impacted by climate change, shade may have opposite effects, and may reduce levels of SS, acids, anthocyanins, and yield. In all regions, regardless of the predicted impact of climate change, shade is speculated to have a negative impact on flavonols and long-term anthocyanin stability. 

As regards microclimate:

Trees benefit vineyards by positively affecting wind patterns and the viticultural microclimate. Although incorporating trees into vineyards can increase management complexity, can reduce yields nearest to trees, and can negatively affect certain grape quality parameters, research suggests that the many above-ground benefits of vineyard agroforestry may very well outweigh their costs. The positive above-ground services that trees provide, such as preventing wind damage and erosion, increasing stomatal aperture and leaf area, increasing photosynthetic capacity, protecting against heat, protecting against frost, and reducing water stress suggest that vineyard agroforestry systems may be a wise solution to the many problems facing modern viticulture, especially considering the extreme temperatures, weather events, pest and disease pressure, and micro- and macro-climatic shifts that are predicted to come in the following years with climate change. 

When agroforestry's above- and below-ground services are paired with its ecosystem services (water purification, pollution mitigation, carbon sequestration, biodiversity conservation, maintenance of  a beautiful landscape aesthetic) "the case can be made that agroforestry's applications in vineyards have the potential to create regenerative viticultural systems that are able to both resist and mitigate many of the issues that modern viticulture is presented with" (Favor).

I will be providing greater detail on agroforestry above -- and  below-ground services -- and their parameter impacts -- in future posts.

 

©Wine -- Mise en abyme

Corsica's Corse-Calvi AOC, the grape source for Etienne Suzzoni's Clos Culombu Blanc

New York City's Some Good Wine is a retailer with a robust offering of off-the-beaten-path wines and is especially deep in Corsican wines. After going in for a second case of their 2018 Etienne Suzzoni Clos Culombu Blanc (produced in the Corse-Calvi region of Corsica), I thought the region, estate, and wine were deserving of a deeper dive. 

Corsica

Corsica has been described as "a mountain planted in the middle of the Mediterranean ... dotted with heavenly beaches and picturesque villages surrounding a central massif. A French territory since 1768, Corsica nevertheless proudly retains its Italian charm and influences ..." (opimian.com).

As illustrated in the map below, Corsica has four primary AOCs (Vin de Corsi, Ajaccio, Patrimonio, and Vins de Coteaux-du-Cap-Corse) and five subzones under Corsi AOC.

Corsican wine regions (Wikipedia)

The island experiences hot summers and sunny autumns with little rain. Significant diurnal temperature shifts yield the cool evenings which are beneficial for freshness and acidity retention in grapes. 

The northern part of the island is schistous and, thus, favorable to the Vermentinu variety. The south has limestone and clay soils and is heavily planted to the red variety Sciaccarella while the east has sandy granite soils which yield excellent white, red, and rosé wines.

Corse-Calvi

Corse-Calvi, the subregion home of Etienne Suzzoni, is hot, dry, and windy in the summertime (favorable for the cultivation of vines and olive trees and in the fight against fungal diseases) and mild and wet in winter. Spring snow-melts help to replenish the area's water table. The climate is modified by the protective shield of Mount Curto and the proximity of the sea which act in concert to reduce the risk of spring frosts and hail.

The region's monogranitic soil is comprised of crystalline metamorphic rock with high silica content and rich in potassium, magnesium, and manganese. The basement is a 350-million-year-old granitic platform whose gradual erosion has yielded sandy loam soils with contrasting textures and structures:

• Extremely sandy soils in the foothills
• Increasingly loamy -- sometimes even clayey -- soils in the plains.

Rounding out the mix is ancient alluvial clay-loam soils carried down from Montegrossu.

The Estate

The Suzzoni estate began with plantings of Niellucciu vines in 1973 by Paul, the eldest son, and his father in the communes of Lumiu and Montegrosso. The grapes from these vines were first vinified in 1976.

Etienne, the youngest son, took control of the estate in 1986 and, given his belief in the terroir and wines of the region, pursued an expansionist policy. Today the estate is comprised of 64 ha of vines, 12 ha of olive trees, and 30 ha of meadows and oak groves suitable for cattle grazing.

A total of 19 grape varieties are planted on the estate; 65% of the grapes grown are red varieties. The primary red varieties are Niellucciu (21%) and Sciaccarello (17%) with Vermentinu (31%) as the primary white. The vineyard is divided into 27 parcels planted at elevations ranging between 50 and 150 m.

The estate has always been farmed in an environmentally friendly manner and this was underscored by the 2013 organic certification (ECOCERT) and current adoption of biodynamic practices.

The Wine

The 2018 Clos Culombu Blanc is a 100% Vermentinu that was macerated on the skins in the press for between 6 and 8 hours prior to fermentation with indigenous yeasts in stainless steel tanks. The wine was aged on the lees for 5 months.

When chilled, this wine has a pleasant, restrained nose of perfumed white fruit with hints of ginger, herbs, mint, and lychee. Bright acidity and juicy on the salivary glands. Lemon-lime with a coating on the palate and a decidedly bitter aftertaste. Screams for shellfish. Late-arriving salinity not as intense as is the case for Assyrtiko/Carricante/Timorasso.

As it warms up, the wine becomes more broad-based and open. Less elegant. Still citrus but less intense and more orange than lime. Easy drinking wine that complements, and benefits from, close association with food. I use this wine as my daily drinker.

©Wine -- Mise en abyme