Gaja Winery agronomical practices aimed at promoting vineyard flexibility

The Gaja wine making process has been the same since 2000 but its agronomical processes have changed within that time frame to accommodate the unpredictability and warming associated with climate change. So said Sarah at the start of our tour and tasting at the Gaja Winery on May 15th of this year. In highlighting this unpredictability, Sarah pointed to the hail that the region experienced in April; hail that came after two weeks of warmth that had encouraged the growth of young, delicate leaves.

To combat this emergent new-normal, the estate has to be flexible in the vineyard. In the course of our conversation Sarah spelt out a number of practices that they have employed in pursuit of this flexibility.

Cover Crops
Grass planted between the rows and tailored to the resident soil. For example, if the soil is compact, cover crops with strong roots will be planted in an effort to open up the soil. One of the many benefits of cover crops is its nitrogen-fixation capability but if the need is to reduce nutrients in the soil, a different type of cover crop can be planted.

In a vintage like 2014, there was a need to reduce the humidity in the soil so the grass was cut three or four times a week in order to remove water. In 2015, a dry period, they did not cut the grass and the carpet of dry grass helped to keep the moisture in the soil.

Most Piemonte vineyard rows are oriented horizontally (Giropoggio), but, since the 1970s, Gaja vineyards have been oriented vertically. This orientation, according to Sarah, slows down sugar production but can contribute to soil erosion during periods of heavy rain. Cover crops are impoprtant in limiting this erosion.

Staffing
Gaja has 96 ha of vineyards spread between Barbaresco and Barolo and applying the estate's agronomical principles consistently requires skilled, competent, and committed employees. Towards this end, Gaja provides housing to its employees in close proximity to their work locale. There are currently 85 employees living in 26 houses distributed across the Langhe holdings. The degree of skill and commitment is reflected in the fact that only eight Gaja employees are allowed to prune the vines; and five of them are second-generation. This degree of focus and specialization allows the estate to maintain high levels of quality over all its holdings for extensive periods of time.

Scion Selection
The average Gaja vine is between 50 and 55 years old. At the end of each growing season, vineyard employees will identify the vines which performed best that year. Cuttings will be taken from those vines and planted in the nursery. If there is a need to replace a damaged vine, one of these "superior-performing" cuttings will be deployed.

Biodiversity
There is a concerted program to increase biodiversity in the vineyards. For example, there are 45 beehives scattered around the vineyards. These bees help with the pollination of the cover crops and thus aid in the advancement of the flora and fauna that they support. "The spic and span approach is not the best way to keep balance in the vineyard," Sarah said.

Sarah making one of her many points

Cypress trees are not native to Piemonte but there are in excess of 250 of them scattered across the Gaja vineyards. In addition to Angelo liking the shape of the trees, their compact structure affords protection for smaller birds from marauding larger predator birds. These smaller birds and bats are major consumers of insects.

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Cultivar, Rootstocks, and Trellis Blocks of the W-MEA Viticultural Model

I began the "fleshing out" of the Wine -- Mise en abyme (W-MES) Viticultural Model with an elaboration of the Site Complex and a comparison of the best practices elements to the Masseto site conditions. In this post I continue this "fleshing out" by detailing the elements of the Vineyard Establishment Complex (identified below within the red oval). As before, I will attempt to identify best practices and compare them against the Masseto conditions where data are available.

Variety
A number of factors are considered in selecting the variety (or varieties) to be planted: (i) experience of other vineyards in the area; (ii) the quality of the variety; (iii) the speed at which it completes its annual reproductive and vegetative cycles and how do those cycles match to the climate of the region; (iv) the yield potential; (v) adaptation to climate; (vi) adaptation to soil conditions; (vii) its resistance to disease; and (viii) the varieties that are allowed by existing legislation (in an area where that is a concern).

The climate of a grape-growing region will determine, to a large extent -- and all things being equal -- both the grape varieties that can be grown and the styles of wine that can be produced. The climatic requirements for successful viticulture include: a growing season long enough to mature both the fruit and vegetative aspects of the plant; production of sufficient carbohydrates to ripen the fruit as well as to maintain future productive potential; and an adequate supply of water.

The common wisdom holds that varieties produce at their best when grown at the coolest margins of viable ripening. Grapevines are selected either through mass or clonal selection and cuttings are grafted onto rootstocks based on the attributes required.

Rootstock
Most of the world's quality wines are based on vitis vinifera, a species which, when grown on its own roots, will succumb to attacks from phylloxera and parasitic nematodes. This problem has been solved by grafting the vitis scion onto phylloxera- and nematode-resistant rootstock.

Vine vigor and soil capacity are additional important inputs into the rootstock-choice decision. Varieties with large canopies (high-vigor varieties) can become less fruitful over time (thus reducing the capacity of the vine) due to reduced cluster number and size. Dr. Andy Walker of UC Davis defines vine capacity as "the ability to grow and produce foliage, roots, and fruit and to establish a trunk." According to Dokoozlian and Kliewer (AJEV 46, 1995, pp. 209-218), vigor is used to describe the growth capacity of grapevines, with those having "large dense canopies and low sunlight exposure ..." being referred to as high-vigor vines. Dense canopies can be detrimental to vine yield in that (i) the plant is deploying its resources in "unproductive" areas and (ii) they reduce the amount of light getting to internal leaves. And human activity (with the related costs) is required to reduce this physical manifestation of vine vigor and re-direct the vine's resources to more productive use.

Soil capacity is a function of the water-holding capacity and mineral wealth of the soil. Vine capacity, on the other hand, is the soil capacity plus the levels of carbohydrates stored in the vine trunk and cordons. Growers seek to blunt the upside of vine capacity by employing low-vigor rootstocks but, in most cases, capacity will trump vigor.

Rootstock(s) utilized in the vineyard environment should be (http://iv.ucdavis.edu/files/24347.pdf):

• Resistant to present and potential soil pests
• Suitable for the soil’s texture, depth, and fertility
• Compatible with soil chemistry (pH, salinity, lime content)
• Favored for the anticipated soil water availability, drainage, and irrigation practice
• Appropriate for the vineyard design
• Appropriate for the fruiting variety’s growth and fruiting characteristics.

Trellis
The rationale behind vine training systems is (i) an understanding that increasing the exposed leaf area improves fruit quality, (ii) that exposure of leaf area can be manipulated by training, and (iii) training alters the microclimate of the canopy. The amount of leaf area that can be exposed to the sun is a major consideration in the choice of a training system. It is affected by (Reynolds, Andrew G., and Justine E. Vanden Heuvel, Influence of Grapevine Training Systems on Vine Growth and Fruit Composition: A Review, Am. J. Enol. Vitic. 60(3), 2009, p251):

• The disposition of the bearing units
• the Trellis height
• The associated type of training.

Growth, yield, and quality are directly proportional to the ratio of exposed leaf area to fruit weight with a range of 7 - 14 cm² total leaf area/gram of fruit required to achieve full fruit maturity. The higher end of the range should be pursued in colder climates in order to ensure that the vine can complete its important physiological functions (Reynolds and Vanden Heuvel).

The trellis serves as the framework within which the vines are trained and supported and must (Paul Domoto, Constructing a Vineyard Trellis, Presentation, Iowa Grape Growers Conference, 2002):

• Be strong enough to support large crops and withstand high winds
• Last for 20 or more years with routine maintenance.

One of the most important considerations in trellis selection is the size of the canopy that it will be supporting. The vines growth potential has to be taken into consideration in order to ensure that it will bear the weight of the vine at maximum vegetative growth. The factors which drive vine growth potential are as follows (http://www.ucanr.org/sites/intvit/files/24348.pdf):

• Temperature
• Annual rainfall
• Sunlight exposure
• Winds
• Soil texture
• Vine rooting depth
• Pre-Plant soil preparation
• Cultivar
• Rootstock
• Cultural practices

Other elements that factor into the trellis decision are (Reynolds and Vanden Heuven):

• Plant and row spacing
• Row orientation
• Establishment costs
• Equipment requirements
• Desire for mechanization.

The details of the model elements for the W-MEA Model Vineyard Complex are provided in the table below. Red-colored text indicates a best-estimate.

      Masseto Vineyard Versus the W-MEA Viticultural Model -- Vineyard Complex

Block	Component	Element	Optimal Value	Masseto Position
Variety	Nomenclature		Depends	Merlot
	Climate Adaptation		High	High
	Soil Adaptation		High	High
	Local Custom		N/A	Compliant
	Variety Quality		High	High
	Yield Potential		Balanced	High
	Disease Resistance		High
	Allowed by Regulation		Compliance	Compliant
Rootstock	Nomenclature		Depends	N/A
	Soil Pest Resistance	Phylloxera	Med-High	Med-High
		Nematodes	Med-High	Med-High
	Soil Qualities Suitability	Texture	Loam, sandy loam	Clays
		Depth	Ø  3 feet	N/A
		Fertility	Low-Med	High
	Soil Chemistry Compatibility	pH	6.0-6.8	N/A; assumed high
		Salinity	Threshold 1500 μmho/cm	N/A
		Lime Content		N/A
	Water Availability	Drought Conditions	Adaptable	N/A
		Wet Soils	Adaptable	Inhibits performance
Trellis		System	Depends	Spurred Cordon
		Strength	Wind resistant; supportive of vine growth potential	Compliant
		Longevity	Ø  20 years	N/A
		Plant and Row Spacing	2.5 m between vines in Bolgheri	3 m x 0.85 m
		Row Orientation	Depends	Perpendicular to the fall line of the slope
		Set-Up Costs		N/A
		Equipment Requirements		N/A
		Mechanization Plans		N/A

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Evaluation of the Masseto Vineyard against the W-MEA Viticultural Model -- Site Complex

Masseto is one of the the world's leading Merlot wines and its 6.63 ha vineyard is ensconced within the confines of the larger Ornellaia vineyard in Bolgheri, Tuscany.

Source: masseto.com

I have recently written a number of posts on the Masseto viticultural environment and will use the generated data to map said environment to the Wine -- Mise en abyme (W-MEA) viticultural model (pictured below) and to compare the results to optimal situations/practices. This post will cover the elements included in the Site Selection class.

The table below shows the fleshing out of the elements of the Site Complex of the W-MEA model, the optimal or industry best practice for each of the elements, and the Masseto position in each of the areas. Data for the Masseto column have been obtained from public sources. Where reasoned guesses are substituted for real data, the entry will so indicate.

                    Masseto Vineyard and the Detailed W-MEA Model -- Site Complex

Complex	Block	Component	Attributes	Element	Optimal Value	Masseto Position
Site	Climate	Macro			Marine west coast; Mediterranean	Medit.
		Average Temp. (°C)			15 – 19	14.5 – 16.9 (Bolgheri)
		Degree Days			> 1750	N/A
		Rainfall	Cooler Region		500 mm/yr	600-650 mm/yr
			Hotter Region		750 mm/yr
	Physical Charact.	Elevation			At or near highest feasible point; within thermal belt	120 m at highest point
		Slope			Slight to moderate incline	10%
		Aspect	Cool Region	Cool	Southern	SE
			Continental		Eastern, northern, northeastern
		Shape			Convex	Convex
		Soils	Physical Attributes	Internal Water Drainage	> 2 in/hr	Clay retains moisture
				Water-Holding Capacity	<  0 - 10 in/in of soil	N/A
				Effective Rooting Depth	>  3 feet	N/A
				Moist Bulk Density	< 1.5 gm/cm³	N/A
				Color	Depends	Taupe to light brown
				Texture	Loam; sandy loam	Heavy soils with clumping clays
				Rock		Pebbles in upper portion
				Structure		Loose clays & sand in upper; 40% clays in mid; less clay lower
				Hardness		N/A
				Root density		N/A
				Fertility	Low-med	High
			Chemical Attributes	Nutrients		N/A; assumed high due to clay content
				pH	6.0 – 6.8	N/A for vineyard; region ranges between 6.93 and 8.55
				Organic Matter	1 – 3%
				Toxic elements		None
				Cation exchange capacity		N/A; assumed high given clay content
			Pests and Diseases	Phylloxera		Assumed
				Nematodes		Assumed

There are no "stoppers" in the Masseto siting of its vineyard. The regional pH is somewhat problematical but can be "worked around." The fertility is not optimal but the use of appropriate rootstocks can help to mitigate the issue. While the soil is not sandy loam, clay soils are considered favorable for Merlot grapes and working the soil to mitigate clumping aids in making it hospitable for vines.

Subsequent posts will address the Vineyard Establishment and Cultural Practices Classes of the Viticultural Model.


Revised 12/23/14 to modify table headings and post title


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