Acid-Tripping in the Pfalz

Germany established its first tourist “wine route”, the Deutsche Weinstrasse, in 1935 in the Pfalz.  The road officially spans 85 km, beginning just south of Worms and ending at the “Wine Gate” (Deutsches Weintor) in Schweigen, at the French border.  The Pfalz’s most historic wineries and best-known vineyards are located in the region’s northern sector, the Mittelhaardt.  Life appears to move quietly along in pleasant little townships like Forst, Gimmeldingen and Deidesheim; these picturesque villages, marked by church steeples, sleepy town squares and other bygone charms, are a far cry from the industrialized Rhine River Valley a few miles to the east.  The winemaking towns of the Mittelhaardt nestle into the gentle eastern flank of the Haardt hills in a tidy line and look outward over the broad, flat expanse of the Rhine River Valley.  The eastern edge of the Palatinate Forest marks the crests of the Haardt hills—which rarely rise higher than 500 meters—and acts as a barrier to wind, casting long evening shadows over those vineyards closest to the ridge.  The southern portion of the wine route, the Südliche Weinstrasse, had long been casually disregarded due to the indifferent quality of its wines, but a few select producers—Ökonomierat Rebholz, Friedrich Becker, Dr. Wehrheim and Herbert Messmer—have launched the reputations of villages like Birkweiler, Siebeldingen, Schweigen, and Burrweiler. 

Looking eastward toward Forst and the Rhine Valley from Kirchenstück

With 22,734 ha of vineyards, the Pfalz is the second largest anbaugebiet in Germany and the country’s largest producer of Riesling.  Over a quarter of Germany’s 20,627 ha of Riesling vines are located in the Pfalz—in fact, the region has more acreage devoted to the grape (5,567 ha) than the entire country of Australia (4,256 ha), or the nations of France (3,350 ha) and Austria (1,643 ha) combined!  From these thousands of hectares, the Pfalz produces a fuller-bodied style of Riesling with a higher degree of alcohol than its northerly counterparts.  The wines reflect the region’s uniformly sunny and dry climate: the Pfalz’s 1289 sunshine hours (April to October) and 21 inches of rain annually are among the highest and lowest, respectively, of Germany’s regions famous for Riesling.  Of course, Riesling is not the whole story.  Like its northern neighbor Rheinhessen, the Pfalz has a wide variety of grapes in production, including Spätburgunder, Grauburgunder, Weissburgunder, Dornfelder, Scheurebe, Müller-Thurgau, and Portugieser.  Sauvignon Blanc is gaining ground as its popularity increases domestically, and one can even find a little Sangiovese hiding amidst the region’s vineyards.  Underneath this myriad of grapes is a complex layering of soil and bedrock formed over the uncountable years of geological time.     

Soil and Riesling

Some 250 million years ago, primordial rivers swept alluvial sediment—sand, clay, and silt—into the vast plain that would one day become the Pfalz.  Compacted over eons and colored by iron oxide, red sandstone today provides the foundation for the Palatinate forest and the Haardt hills.  Additionally, volcanic activity pushed magma to the surface of the earth’s crust, resulting in layers of basalt, and some 50 million years ago tectonic activity and the rise of the Alps caused the Rhine basin to collapse.  The Haardt hills on the west and the Black Forest on the east rose sharply as the land between them sunk and filled with seawater.  Over time, the area dried up again, but traces of the sea remained: calcareous deposits from this period of submersion formed limestone (kalkstein).  As millions of years passed slowly by, water, erosion and wind filled the Rhine basin with sand, gravel, and loess—the latter is the Pfalz’s youngest soil, arriving after the last ice age.  During that glacial age, rivers of ice advanced into Europe, grinding primary rock beneath them into pulverized, fine grains.  As the glaciers retreated with warming temperatures, this dusty combination of pulverized rock and other small sediments—loess—was unleashed upon the winds, and much of the soil settled beneath the Palatinate Forest in Pfalz.  Once covered by vegetation, the loess held firmly in place; today it is one of the few truly arable soil types still cherished for wine production.  Sandstone, limestone, basalt, loess, loam, gravel, red slate, clay—the Pfalz, like Alsace, its neighbor to the south, has an incredibly abundant wealth of soils and strata. VDP producers in the Pfalz and elsewhere often label a middle tier of Riesling wines by soil type, trumpeting its importance to the consumer.  The relationship between Riesling and the patchwork maze of soils beneath it is suddenly layered with meaning: can the soil supersede the climate?

The refrain from scientific quarters has been pretty loud: you can’t taste rocks.  This, of course, leaves sommeliers, who make a living pretending to taste rocks (and occasionally licking them too, for good measure) look rather silly.  And there is no grape in the world that is more associated with the soil beneath it than Riesling.  Think about the last time you blinded German Riesling: just how automatic was that “Slate!” minerality call?  Some relationship between the soil and the vine, something beyond the simple control of vigor, had to lie underneath.  If the focal point of the VDP’s Grosse Lage/Erste Lage category is site specificity, rock had to matter.  So the German scientists went looking for terroir.  In a seminar at the 2012 Mainzer Weinbörse (VDP Fair), Dr. Ulrich Fischer spelled out his results from years of study on the subject: the type of bedrock seems to make a significant impact on the sensory qualities of Riesling.  While the relationship is perhaps not direct—a wine grown in chalk may not actually taste like chalk—it is definable by the presentation of acidity and aromatic components in the wine.  For instance, Riesling grown in alkaline soils like limestone and chalk will generally produce a wine of higher pH and lower perceived acidity than Riesling grown on sand or slate.  Even though calcium and potassium compete for space in the soil, alkaline soils in Germany tend to be higher in potassium content than acidic ones, and both calcium carbonate—the building block of limestone—and potassium act as a buffer to acidity in wine.  In fact, a method of natural de-acidification used by Riesling producers is a pre-fermentation cold soak, during which the must leaches potassium from the grape skins.  Potassium and tartaric acid will then precipitate out of the must as potassium tartrate.  Heck, calcium carbonate is widely used to relieve heartburn.  Are these findings applicable beyond Riesling?  In Burgundy, Sancerre or Champagne vignerons may scratch their heads, and promote the opposite view in regards to their calcareous soils.  In fact, most French (and other) sources regard alkaline soils as a propeller of acidity in wine; Germans winemakers seem to unanimously disagree, at least in regards to Riesling.  Perhaps the buffering effect of calcareous soils, measured against slate—which does not buffer acidity at all—is just as marked as the difference between limestone and clay in the Côte d’Or.  Most agree that heavier, wetter clay soils produce wines of higher pH.  Like Dr. Fischer, Dr. Peter Böhm of the Terroir Hessen project in Germany is conducting an ongoing series of research into the relationship between Riesling and soil.  His studies seem to confirm the buffering effects of calcium carbonate in calcareous soils, and show that loess, marl and clay soils tend to reduce the perception of acid in the finished wines as well.  Sandy soils, like slate, emphasize acidity, as they do not have any significant buffering effect on pH.  As Dr. Fischer proposes, “Acidity might be the most significant indicator of terroir.”  But is it the only one?

Dr. Fischer conducted a number of winemaking trials focusing on different soil compositions within a single region.  The Pfalz presented an obvious opportunity: in one trial, Bassermann-Jordan vinified dry vintage 2004 wines from two vineyards, Deidesheimer Kieselberg and Forster Pechstein, in exactly the same fashion.  The main variable was the soil composition: Kieselberg rests on sandstone (buntsandstein) soils and contains a high proportion of gravel, whereas Pechstein is characterized by a basalt bedrock and loam.  The two sites, only a mile apart, yielded pronounced aromatic differences: Pechstein gave the impression of exotic fruit (passion fruit, mango and cantaloupe) and grapefruit, whereas Kieselberg produced a wine of less intense aromatics, more vegetal notes, harsher acid, and a generally harder mouthfeel.  On the other hand, a second experiment compared Riesling from Ürziger Würzgarten (in the Mosel) and Birkweiler Kastanienbusch (in the southern Pfalz).  Both sites share similar bedrocks of red slate, or rotliegend, yet they are over 100 miles apart.  Despite the Mosel’s cooler climate, perception of aroma and acid between the two wines was remarkably similar.  The major difference in taste—a more substantial bitterness in the Pfalz Riesling—could simply be attributed to its higher alcohol content, as ethanol enhances our perception of astringency.  Further experiments were conducted in warmer years—2005 Rieslings from Kieselberg and Pechstein were less dramatically different—and across vintages.  Whether produced in the Mosel or elsewhere in Germany, wines from blue slate delivered common apple, citrus, vegetative and metallic characteristics, yet Würzgarten maintained a more vibrant sweetness and cantaloupe fruit, akin to the wines of the Roter Hang.  A relationship between floral character in Riesling and sand emerged as well.  Sandy soils are unable to retain water, encouraging premature leaf senescence.  Leaf yellowing and loss subjects the grape clusters to sunlight, and increased solar radiation promotes the development of terpenes—the root of floral aromas—in the grapes.  On the other hand, Dr. Fischer and Dr. Böhm both commented on sand’s tendency to produce Riesling of lower fruit intensity and lessened overall aromatic character.  Is a simultaneous heightened development of terpenes and lowered intensity of aromatics for a single soil type a contradiction in terms?

Dr. Fischer’s study sheds light on the importance of bedrock, and gives a corresponding nod to the importance of vine age and root depth.  In the Roter Hang, famous throughout the wine world as the classic zone of quality production in the Rheinhessen, the red slope is reputably composed of slate, yet a walk through the vineyards reveals seemingly fertile, if very red, clay.  Rotliegend slate is the bedrock underneath the clay, into which the vine roots anchor.  In Westhofen to the south, Klaus Peter Keller has grafted a vineyard block of 70 year-old Silvaner vines in Morstein over to Pinot Noir.  In Morstein the topsoil is clay, but by grafting the Keller estates hopes to retain the nearly 50 meter-deep root system, which digs into the weathered limestone strata beneath.  If bedrock can profoundly influence the aromatic qualities and acidic shape of a wine, then wines from single sites should and will undergo metamorphoses in character as their roots bore through the topsoil and into the rockier layers underneath.

Soil color also plays a part in shaping the wine.  The color of soil correlates to the amount of organic material it contains and its ability to retain water—darker soils tend to hold water longer, and contain more organic matter.  An old viticultural maxim dictates that red varieties grow best in red soils, and white varieties grow best in white soils.  This may hold true: Dr. Hans Schultz, Director of the Geisenheim Institute, suggests, “Soil color determines the amount of energy reflected back into the fruiting zone and the amount of energy kept in the soil.  It indirectly determines thus fruit temperature and soil temperature.  The spectral signature of the light reflected depends on soil color and triggers the activity of certain enzymes in the fruit – for example those involved in color formation.”  Red soils encourage the development of pigment.  In addition, the darker the soil, the more it tends to retain—rather than reflect—heat.  Thus, vines planted in the blue-black Hünsruck slate of the Mosel receive far less direct solar radiation during the warmest months of summer than those planted in red clay, loess, or chalkier soils; but the slate keeps the vines warmer at night.  Lighter soils, on the other hand, encourage more photosynthesis throughout the growing season as they intensify the sunlight hitting the canopy.  

What does any of this really mean?  Soil science as it relates to viticulture might as well be a discipline in its infancy; I often think that the scientists who conduct these trials may never actually understand the spirit of wine; conversely we sommeliers usually make only a halfhearted attempt at grasping the underlying science.  We worry that science cheapens the art and often make only basic inquiries.  In our wines we tolerate the lack of absolutes but we require them when we attempt to understand the viticulture.  This is the effect of this climate, or of that type of soil.  We try to reduce everything to a single canned answer, in the way we often memorize grape varieties or synonyms or sub-regions, and go crazy when we hear conflicting answers to seemingly straightforward questions, such as, “What is the effect on wine acidity in limestone soils?”  Do the French argue that chalk and limestone promote acidity because their grape-growing regions most notable for these soil types tend to be in the north, anyway?  And what about clay, for that matter?  It reduces acidity, unless it prevents the grapes from ripening fully, which is what heavy clay tends to do….  Maybe the scientists should revisit Occam.  Or should we resort to a mad lib, courtesy of sommelier Steven Grubbs: "I'm not a chemist, but___________although____________and____________unless_________.  Who knows, though?"  Was it Fitzgerald who remarked that the mark of a first-rate mind is the ability to hold two contradictory ideas at once?

Dry vs. Sweet

All of this brings us back to the Pfalz, Germany’s most diverse geological landscape, and another question: is dry Riesling the best lens through which to view terroir?  2007 marked the first year in modern times in which dry German Riesling supplanted those at the sweeter end of the scale in quantity of production.  Nowhere is the focus on dry Riesling clearer than in the Pfalz.  In 1996, the region launched the VDP’s “Grosses Gewächs” concept; among the best producers today—with the notable exception of Müller-Catoir—sweet wines have become an afterthought.  Do sugar and ripeness obscure the vineyard?  At Geisenheim, scientific studies suggest that the distinctions of “terroir” are muted at Öchsle levels above 100°, an argument that dovetails nicely with Dr. Fischer’s research on reduced sensory differences in hotter, shorter growing seasons like 2005.  Even if true—and we often argue that ripeness and minerality are on a see-saw—this certainly does not preclude classic Spätlese or Auslese.  Producers can pick for the latter category at 92° Öchsle in the Pfalz.  Dry “GG” wines are harvested at Spätlese level anyway, and one producer in Kallstadt, Koehler-Ruprecht, harvests every trocken wine the estate releases at Auslese ripeness, and sorts out the Prädikat labeling in the winery.  Must weights are skyrocketing in general in the modern, hotter Germany.  In the Pfalz, the growing season is twenty days longer than it was two decades ago—Riesling harvest dates may be earlier as a result, but must weight is increased.  Average acidity for Riesling in the 1980s clocked in at 15.5 g/l, whereas in a modern high acid vintage like 2010 we only see seven, eight, or nine g/l of acid in the Pfalz.  Does the wine still need the sugar for balance?  Dry Riesling has become the choice of the German consumer, but sommeliers and wine professionals in Germany’s biggest export market—the USA—are not wholly convinced.  Paul Grieco, James Beard Award Winner and “Summer of Riesling” evangelist, considers Spätlese to be the best conveyer of terroir, and Terry Theise has been a vocal critic of dry German Riesling for some time.  If the definition of terroir includes a historical component, as it must, then one may argue that the current crop of dry Rieslings has an antecedent dating back to before the Second World War.  Conversely, the most penetrating criticism is the question of age: will anyone be enjoying the new Grosses Gewächs bottlings a half-century down the road?  In the cellars of Bürklin-Wolf, we tasted a magnificent 1971 Riesling Auslese from Leinhöhle, a small vineyard in Deidesheim sandwiched between the more prominent sites of Langenmorgen and Kieselberg.  The current owner, Bettina Bürklin, switched the estate’s focus to dry wines when she took over the estate in 1992.  While top dry bottlings in recent vintages showed well, it was difficult to imagine the young wines holding on like the 1971.  On the other hand, Bettina seemed a shade dismissive of the Leinhöhle, calling it, in a word, “sweet”.

Top Producers and Sites in the Pfalz

Collectively, Bürklin-Wolf, Bassermann-Jordan and Reichsrat von Buhl are the “3 Bs”, long regarded as standard bearers for quality in the Pfalz.  These are not small estates: Bürklin-Wolf holds 85 ha of vineyards, Bassermann-Jordan has 49 ha, and von Buhl maintains 55 ha.  Yes, a thick air of commercialism hangs over all three—tours are likely led by export managers or other salesmen, trotting out the usual buzzwords—but their contributions to the historical development of the Pfalz as a premier wine region is not in doubt.  Mid-tier efforts from Bürklin-Wolf, a recent convert to biodynamic viticulture, remain reasonably distinctive, and wines from their top sites, like Forster Pechstein and Forster Kirchenstück, can be exemplary.  The 1828 Royal Bavarian Land Registry, a principal source for the VDP’s current classification, marked Kirchenstück (“Church Parcel”) as the Pfalz’s top vineyard.  It is certainly the warmest.  When we arrived at Kirchenstück on the first day of May in 2012, flowering had already begun; at Rüdesheim in the Rheingau budbreak had only occurred about ten days beforehand!  Even in Forst itself, just a short walk east of the vineyard, almond trees often flower two weeks after a single tree within the vineyard itself blooms.  Only eight producers—including all “3 Bs”—have a slice of this treasured 3.7 ha vineyard, and Bürklin-Wolf’s bottling is perennially among the top wines of the Pfalz.  While we were not offered an opportunity to taste the wine while visiting the estate, we did have an opportunity to compare all three producers’ efforts from Pechstein.  For me, the Bürklin-Wolf 2009 Pechstein “GC”—Bürklin Wolf labels their top wines with shorthand for “Grand Cru” rather than “Grosses Gewächs”, a practice tolerated by the VDP—came out on top.  Pechstein, a southeast-facing, languid slope comprising 12 ha, sits on basalt bedrock and red sandstone.  There are volcanic rocks closer to the surface here too: workers in the past actually carried dark basalt stones from further afield into the vineyard in an effort to improve the soil’s capacity for heat retention.  Bürklin-Wolf’s bottling displayed the character attributed to Riesling grown in basalt: mineral grip, spice, exotic fruit, and powerful concentration.  Bassermann-Jordan’s 2009 Pechstein showed fuller fruit notes, plunging headlong into pineapple and passion fruit, but perhaps lacked some of Bürklin-Wolf’s nerve.  Von Buhl’s Pechstein 2009 also had a luster of forward fruit, but tied it together with a fiery mineral finish.  At this level, all three estates can make excellent wines, but if there was a period during which the “3 Bs” had a lock on premier quality in the region, that period is over.

Inside the cellars at Büklin-Wolf.  One hundred years ago, an inch of water would have covered the floor, but the water table in Pfalz has receded.

Ascendant producers in the Pfalz include A. Christmann.  From his family’s estate in Gimmeldingen, Steffen Christmann—current head of the national VDP—is crafting concentrated, dry wines that are among the best the Pfalz has to offer.  Christmann firmly believes that dry Riesling is the modus operandi for the region, and he produces clean, botrytis-free wines with little residual sugar—never more than 5 g/l—hoping that this will give voice to his vineyards.  Christmann’s 2010 Grosses Gewächs Reiterpfad (a Ruppertsberg site) seems at odds with Dr. Fischer’s suggestion that vineyards planted in sandstone should produce Riesling of harsher acid and tighter aromatics; the wine seems rather lush and full, showcasing tropical fruits and elderflower aromatics.  The acid, however, was off the charts and completely in line with the suggested lack of buffering in sand.  A Königsbacher Ölberg 2011 bottling seemed rounder and more giving—was this the presence of calcium carbonate in the soil rearing its head, or simply the gesture of a more forward vintage?  A neighboring site, Idig, is the source of Christmann’s finest wines and a near-monopole for the estate.  We tasted a decade’s worth of Riesling vintages from his 5 ha plot: its creamy, custard-like palate develops slowly over time in the bottle, and notes of lemon oil and something akin to thyme flowers seem to remain consistent throughout the young wines.  The wines’ acidities remained electric despite a presence of chalk in Idig’s marl soil, but flesh and weight balanced the nerve.  These wines are as clear a testament to the quality of dry wines in the Pfalz as can be found.  For me, there is only one other grower currently producing dry Pfalz Riesling with this level of skill, albeit with a more austere approach: Rebholz.

As we approached Ökonomierat Rebholz’s winery in Siebeldingen, we crossed a piddling brook called, rather hopefully, the Queich River, which marked the French border from the mid-1790s until the first Napoléon’s final defeat in 1815.  Hansjörg Rebholz—whose grandfather Eduard held the honorary title “Ökonomierat” (agricultural counselor) and positioned the winery toward its current natural approach, eschewing chaptalization and süssreserve—poured a flight of Grosses Gewächs Riesling, Weissburgunder, and Spätburgunder from the winery’s best sites: Kastanienbusch and Im Sonnenschein.  The Rebholz Riesling style showcases extraction, depth, and concentration, yet the wines display remarkable mineral austerity.  Yellow fruits, smoke, and saline flavors are a common undercurrent.  All of the 2010 wines displayed the characteristically high acidity of the vintage, yet there were differences from site to site.  Rebholz bottles both a “GG” Riesling from “Ganz Horn”, a small vineyard integrated into Im Sonnenschein in the 1971 wine law, and a Riesling from the larger vineyard.  In most of Im Sonnenschein, a shell limestone known as muschelkalk predominates, but in Ganz Horn (“horn of the goose”) the limestone gives way to sedimentary layers of sand and gravel.  In tune with the German rationale, the acidity in the 2010 Ganz Horn Riesling is much more energetic and sheer, whereas the 2010 Im Sonnenschein, grown just a stone’s throw away, is rounder overall.

The Im Sonnenschein wines are excellent, but Rebholz’s most cherished plot lies in the 86 ha Kastanienbusch (“chestnut bush”) vineyard outside Birkweiler.  Enclosed by folds of the Haardt hills on all sides, the vineyard itself is like a hidden viticultural treasure, earmarked as a superior site in the 1828 Royal Bavarian Land Registry but dormant in quality until its resurrection by producers like Rebholz and Wehrheim in the last decade of the 20th century.  It faces due south.  The 30° slope is brick-red with slate and sandstone; Rebholz’s 2 ha of vines, replanted from 1988 to 1992, lie halfway up the hill.  The dry wines from this site age well over the short term—a 2001 tasted at the winery displayed almost Mosel-like filigree, with sweet herb, spearmint, lemon marmalade, honey, and candied fruit notes.  As we sipped the wine, Hansjörg relayed a common analogy in Germany for the trajectory of Riesling: at three years or less, Riesling is in its youth and the aromas are dominated by simple esters; at four to five years the Riesling enters a rather uncomfortable adolescence of petrol; and from five years on the Riesling matures into manhood as terpenes in the wine finally reveal their potential.  Does Rebholz believe that sweet Spätlese might offer a better view of his vineyards in the glass?  Hardly.  In the winery’s marketing literature, Hansjörg writes, “With our wines, we choose to counter the outdated fashion for sweet wines and indifference toward terroir,” suggesting that sweetness and terroir are almost an inconceivable union.

Rotliegend soil from Kastanienbusch

Looking north toward Kastanienbusch

Rebholz uses cultured yeasts in his production, but others ferment their wines “spontaneously”, relying on ambient yeast populations.  Andreas Hütwohl, Assistant Director at Von Winning, a winery in Deidesheim under the same ownership as Reichsrat von Buhl and Bassermann-Jordan, explained how the winery prefers “natural” yeasts and oak, stipulating that the weaker ambient yeasts require the interplay of oxygen to be effective.  Rainer Lingenfelder in Grosskarlbach echoed the necessity of air for successful spontaneous fermentation, but achieves this result by using an old basket press to introduce oxygen into the must during a cold-soak, rather than utilizing casks for the actual fermentation.  Dr. Schultz of Geisenheim and others downplay the “natural-ness” of ambient yeasts, arguing that they are winery—not vineyard—yeasts, and therefore they obscure rather than augment the natural projection of the terroir.  On the other hand, some of Germany’s great estates—J.J. Prüm, Keller, Schäfer-Fröhlich, Wittmann, Bürklin-Wolf, and the talented newcomers of Thörle—indulge in the practice.  Whether ambient yeasts inhibit or encourage terroir, the wines seem generally less fruity and more sulfuric.  Ambient yeast populations actually produce sulfur as a byproduct of fermentation, according to Schultz.  For Von Winning’s more everyday wines, released under the Dr. Deinhard label, they use tried-and-true cultured yeasts and stainless steel; for the estate’s top wines, the producer employs spontaneous fermentation in a moderate proportion of new oak barrels, an uncommon site in Riesling cellars.  When Von Winning’s management argues that wood is a traditional medium for aging Riesling, they are correct, but the vessels of choice historically were larger, neutral casks—the viertelstück (300 liters), halbstück (600 liters), stück (1200 liters), and doppelstück (2400 liters), not new François Frères barrels.  Strangely, Hütwohl insisted that “GG” Riesling in recent vintages sees only a small proportion of new 500 liter barrels, while simultaneously pulling a barrel sample of Kalkofen Grosses Gewächs 2011 out of a 225 liter barrique for us to taste.  Spontaneously fermented or not, Riesling aged in small new wood barrels is just not to my taste.

Some Final Questions

Riesling is not the only game in town—Rebholz’s Weissburgunder can be revelatory with bottle age, Becker’s Spätburgunder is among Germany’s most highly  lauded, and Lingenfelder produces excellent examples, both dry and sweet, of the “son of Riesling”, Scheurebe—but Riesling is the grape by which the Pfalz can be most clearly judged.  We love Riesling because it is transparent.  As producers label mid-level Riesling wines by soil type—kalkstein, buntsandstein, rotliegend, muschelkalk—bedrock is pushed toward the consumer, demanding that we notice and discern the subtle differences in limestone and basalt, slate and sand.  Is this just marketing, or do the Germans believe that the wine-buying public can achieve this level of sophistication?  Are we looking for a thread among the dozens of producers throughout Germany who bottle a "kalkstein" Riesling where one simply does not exist?  What difference does a slight natural buffering of pH make against a larger framework of techniques—bâtonnage, barriques, cold soaks, de-acidification, higher levels of residual sugar, etc.—employed in the service of rounder wines?  Perhaps substituting "9 g/l of residual sugar" for "kalkstein" on a label might be a little more meaningful, if less poetic.  Besides, I believe that we are only beginning to understand the soil's potential to buffer acidity and affect aroma.  As there is little agreement on the buffering capacity of calcium carbonate outside Germany, I think that a "grand unified theory" approach is perhaps misguided.  We may find totally different results for the same fundamental soil types throughout the world.  Different grapes may behave differently.  The German studies may turn out to be true, but only in relation to German soils and Riesling.  Alsace's Clos Ste. Hune vineyard is composed of muschelkalk—I wonder what opinion Trimbach might have to offer regarding calcium?  If and when a grand unified theory of soil and wine acidity emerges, it will probably take up more than a single 3x5 notecard.

  • WOW! the Pfalz is my fav German region. I never knew it had so much Riesling under vine! Great read!

  • great post, great thoughts and threads on the relation between soil structure and wine structure - (and I agree about the (under-estimated) importance of the mycorrhizal activity....)

    I just would say i think the quality of acidity - tartric, citric, malic, etc. - has a good part to play in our perception (malic is for me the more intense, citric fresher, tartric harsher/more sour, acetic bitter and so on and so on... plus they all have a different impact on the pH) and i know that a certain type of acids - like the tartic - will develop more in certain soil/vintage -  conditions than the malic for example... i am curious to know if in this study they analyzed the acidity with the titratable acidity or with a breakdown of the different acids...

    just more food for the thoughts to enjoy even more to taste and drink wines :)

  • Matt, it seems that the Germans are also drawing a parallel between limestone being more concentrated in lower-lying areas.  Wouldn't this fact alone contribute to the buffered acidity?  It would make sense that Germans see limestone as an acid-buffering agent because, due to how it was formed, it tends to exist in areas of lower elevation.  In Germany, these lower-lying areas would produce wines with comparatively lower acidity.  Have the Germans done anything in the way of examining the mycorrhizal differences between limestone and, say, gneiss?  As that's the other determining factor in cation exchange, I think that might help to cast the deciding vote.

  • Great article! Thank you

  • Matt, A great site!  Thank you. There is good discussion of impacts from calcium rich soils in grape growing at by Valerie Saxton.  Curious about impacts of the primary rain times in the German growing regions being during vegetative growth re: calcium uptake greatest between budbreak and veraision, and highest with wet soils.  Is it accurate that most rain in Chablis and Champagne is during dorment season?  What about Calcium uptake via traditionally used rootstocks that differ between growing regions?  Perhaps in one area soil impacts are primarily structural (allowing deep root growth, access to water, and cooling to preserve acid) vs those plus calcium uptake in a different growing region?  Also interesting that calcium in grapes at harvest is primarily in the skins which makes sense with the German natural de-acidification through cold soak (as CaC03 can be used in wineries to de-acidify through addition pre-fermentation).  I am still missing the connection between calcium and calcium carbonate and if having Ca necessitates having CaCO3 in must.  Frustrating when curiosity in one field is stymied by lack of knowledge in another...  But today was the first day of my wine quality control and analysis class (instructor a chemist) so I will try to get some input from her.