Superficially, our soil looks like some of the better bits of the Côte
de Nuits. The soil is composed of clay (25%), limestone gravel (25%), silt
(30%), and sand (20%). In the shallower parts of Grand Cru Romanée St Vivant
you hit Bajocian bedrock at a depth of 30cm, and it’s the same for Tixover.
Shuffling around on your haunches you might imagine yourself to be in Vosne.
The first time I tested our soil, I also submitted samples gathered from across
the Côte de Nuits. The results for Romanée-Conti confirmed it as “a good
agricultural soil”, with macronutrients falling within the 2-3 range of
standard farming indices; endorsing its potential as a wheat field should the
wine business ever go to pot. The ratio of K:Mg in Le Chambertin and Clos de la
Roche was skewed towards potassium, and the pH for all three sites was between
7.8 and 8.3. The results for the Tixover sample closely resembled those of the
Grands Crus. All four had excessive calcium levels.
The second soil test was analysed in France. It introduced me to new
concepts like cation exchange capacity
(CEC), and base-saturation. Our soil
was high in nitrogen and calcium, but weak in iron and magnesium. The ratio
between calcium and magnesium influences soil structure, and soils that are
base-saturated with calcium tend to be more porous than soils dominated by
magnesium. A high Ca/Mg ratio generally facilitates water movements within the
soil - up, down and sideways.
The most recent test, conducted by Albrecht Agriculture, was also the
most thorough, and the results showed worrying discrepancies from the previous
two analyses. Iron was recorded at a critically low level, and the CEC was
measured at 30meq, which is high for a soil that is only 25% clay. The “clay
and colloidal matter” bound calcium and magnesium ions in the ratio of 40:1.
Our soil, Albrecht warned us, was like a sieve. We needed to add magnesium,
lots of magnesium. But at least we were in good company: the three Grands Crus
soils were similarly biased in favour of calcium base-saturation.
Confusingly, iron levels were only measured at 1ppm by the Albrecht
people, but at 15ppm by the lab in Montpellier. We haven’t seen signs of
chlorosis in the vines, so experience suggests the French analysis is the more
accurate of the two. Moreover, despite identifying the chronically deficient
iron levels, the Albrecht analysis didn’t propose any amendments other than the
magnesium. Critics of scientific methodology warn about theory laden data, and
the Albrecht obsession with the calcium:magnesium ratio may explain why in this
instance they missed the low iron count.
CEC is a measure of the nutrient holding capacity of the soil, and
relates principally to the number of internal and external bonding sites within
the sample’s clay and colloidal fraction. The meq measurement was elevated in our sample by the mix of clays.
Smectite, a volcanic mineral, was incorporated into our clay as it sedimented
out, and its inclusion has significantly changed the soils properties. For
Agronomist, Claude Bourguignon, smectite/montmorillonite clays, with their
large internal surface areas, are particularly advantageous for red wine
production. Just why these clays are so interesting to M. Bourguignon is worth consideration.
According to Bourguignon, the soils of Petrus together with most of
Vosne’s Grands Crus (Romanée-Conti may be the exception) are luxuriously
endowed with smectite. By contrast, the illite-kalolinite clays of the white
Grands Crus have much smaller surface areas, and therefore their capacity to
hold and exchange nutrients is considerably lower. Montmorillonite clays are
also distinguishable from other clays by the extent to which they expand when
wetted. Modest water deficits are seen as advantageous in wine production as
they accelerate ripening and generally improve the quality and quantity of
extractable solids from the skins, so a clay that absorbs and holds onto
copious amounts of water would seem anomalous to the requirements of premium
grape production. Montmorillonite clays do have a trick, however. Strong root
growth and function require a good level of root oxygenation. The expansion of montmorillonite
clays can be so dramatic that root growth and function become impaired.
Moreover, the permeability of the clays can decrease due to sealing at their surfaces
after wetting. Thus soils may look wet, puddled even, but this moisture is not
necessarily available to the roots; a case of water, water everywhere and not a
drop to drink. And just as they expand when wetted, so montmorillonite clays
shrink when dried. A sustained period of drought will open up capillaries
within the soil which then become exploited by the vines’ constantly
regenerating mesh of short-lived rootlets. Taking into account the close
connection between vacillations in clay particle size and Bordeaux’s changeable
seasons, it is possible to model a shallow, smectite-rich soil in which the
availability of moisture to the vine roots is almost continually held at
deficit levels;- a terroir very much like that of Petrus, in fact.
Beneath the thin clay loams of Vosne’s Grands Crus is limestone. The
ability of vine roots to populate hard rock is limited, but this fact hasn’t
stopped commentators from positing this hidden union as the very foundation of
terroir. However, a more probable explanation of limestone’s advantage to
viticulture is revealed by a consideration of its physical properties. Limestone
can hold large volumes of water, but, as was discussed in the context of clays,
we must be careful not to confuse capacity with availability. Movement of water through soils is
multidirectional, and limestone can irrigate the clays resting upon it through
capillary action. The extent to which the capillaries are opened will in turn
depend upon the relative expansion of the clays and the degree to which calcium
base-saturation has flocculated these, the most minuscule of soil particles,
into larger agglomerations. In other words, the limestone’s ability to function
as an aquifer is itself dependent upon the structure of the overlying soil. As was
the case with Petrus above, we can imagine a possible balance between local
effects whose equilibrium point sustains the vines at a slight and ultimately
advantageous level of water deficit.
On the Côte de Nuits the mercurial temperament of Pinot Noir brings
colour and texture to the bland realms of geology and pedology. In her
excellent articles on “Calcium in Viticulture”, Valerie Saxton talks of
“terroir ridden France”, and Burgundy can seem like yet another scion of the Republic’s
obsession with taxonomy and hierarchy. So completely pixelated has the map of
Cote d’Or’s vineyards become, that it’s now virtually impossible for outsiders
to see the whole picture. Twenty
years ago, many New World growers censured the Côte d’Or. It just didn’t make
sense: Grands Crus a stone’s throw from modest village vineyards; and Clos
Vougeot, the oversized Circus Maximus
at the centre of this antiquated world, just seemed to lump together everything
that the rest of the classification had painstakingly tried to keep apart.
There are historical precedents for Burgundy’s sub-divisions, but the
acute sensitivity of Pinot Noir coupled to the equally acute sensibilities of
those that tend to it is the more remarkable story of this segregation. One way
of classifying grape varieties is through their differing responses to water
deficits. Anisohydric vines are said
to be drought tolerant, whilst isohydric
varieties are drought avoiding. The divide is not clear-cut, and relates to the
strength of response different varieties show towards hormonal signalling
(abscisic acid) from the drying roots. The stomata of isohydric varieties
progressively close, rationing water uptake and loss, whilst anisohydric
varieties maintain stomatal turgor, such that gas exchange, water uptake and
carbon gain are unimpeded. Isohydric vines are “pessimistic” and anisohydric
vines “optimistic”, inasmuch as the latter carry on as if they expect it to
rain again tomorrow.
Some varieties seem capable of both responses, but in extremis, Pinot Noir is anisohydric, and Grenache Noir
isohydric. Lavish water use, as
exemplified by Pinot Noir, brings with it a vulnerability to sustained drought.
Pinot Noir, by rapidly depleting soil moisture can accelerate itself towards conditions
under which its own metabolic processes become compromised, just like the man
who saws-furiously at the branch he’s resting on. Without the self-buffering
responses of isohydric varieties, Pinot Noir’s own water status is so immediately bound to the vicissitudes
of soil moisture that it takes, in unirrigated Burgundy, a very special mix of
extraneous pedological factors to consistently produce high quality grapes,
i.e. those that are the result of sustained, but not impairing water deficits.
Vosne’s Grands Crus are, indeed, exceptional.
Claude Bourguignon caused me to depart from thoughts of my own soil
analyses and on-going struggle to get consistent data. There have been reasons for optimism in most
of the results, and I don’t doubt the fact that if Tixover’s three blocks of
brashy soil were panelled into Morey or Chambolle you wouldn’t see the joins,
but it’s ridiculous to start talking about terroir, particularly when we seem
to have spent the last few years acquainting ourselves with a whole load of
Nature’s disadvantages. I remember with incredulity, a vineyard owner in Long
Island exploiting the argument that Bordeaux’s Crus were the finest in the World,
and that Bordeaux’s vineyard were flat, and as his vineyards were flat, too, it
followed that his wines were rivals to the Médoc.
As said, there was a time when the majority of New World growers rejected
terroir, portraying it as either a perspicacious piece of marketing, or homey make-believe.
But somewhere along the track these protagonists either gave-up on this line of
attack or lost the argument, because producers in Chile, New Zealand and
Mendoza nowadays reel-off neat invocations about the contingency of their own
vineyard work that wouldn’t sound out of place in Vosne. Wine now seems so exclusively
“made in the vineyard”, it’s hard to know if there is anything left for
winemakers to do. In the New World, terroir has gone from being nowhere to
being everywhere.
The ubiquity of terroir is problematic.
I take from the late Peter Sichel’s remark that only a fraction of
Bordeaux’s vineyards genuinely exhibit terroir-characteristics, that terroir is
a title bestowed like an honour or a peerage, rather than a democratic entitlement
to which anyone with a vine growing up a wall has an equal claim. Accordingly, Richebourg
and Petrus are the exemplars of terroir, the foundations and acmes of a system
in which exceptionality and scarcity are paradigmatic. In this context, the work of Claude Bourguignon,
Gerard Seguin and Cornelius van Leeuwen is so pertinent because they are trying,
in different ways, to cleave some scientific traction into our understanding of
a much abused term. For those who crave more metaphysical accounts of grape
quality, who will never be moved by terms like “vine water status” or “point
quadrant analysis”, there is always Nicolas Joly. But this is to miss the
point. When physicists revealed diamonds’ atomic structure they didn’t stop them
from being a girl’s best friend.
I do share Peter Sichel’s instinct for parsimony, not least because the
over-extension of any term, terroir included, eventually runs the risk of draining
all significance from it. The meaning of words changes over time, and despite
van Leeuwen’s attempts to give terroir intellectual rigour, I feel sure that
the term’s appropriators will win out. “Sense of place” will read like a
postcode.
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