Updated: Mar 26, 2019
As I’ve mentioned in a few of the posts so far, there is great variability of terroir in the 40 miles that make up the Uco Valley. The most obvious is altitude, which rages from a little over 3,000 fasl in the Southeast to the terminal limit of growing conditions at 5,000 fasl in the Northwest. The general rule of thumb is that for every 100 meters of altitude, temperatures are cooler by 1C. This translates to 330 feet/1.8F. This might not seem like much, but when compounded over an entire growing season, it has tremendous impact on ripening since photosynthesis only takes place at above 50F. So, if we do the math, that translates to a potential difference of temperature extremes in the valley of 36F. While the reality is that there is not that much difference, there is significant variation. However, there are several mitigating factors to this average temperature difference. The first is that with these higher elevations come a broader spectrum of more intense sunlight. This pushes the engine of the vine, promoting ripening. Second on the list is that diurnal temperature amplitudes in high elevation sites tend not to be as high as some of the lower lying regions as cool air from the mountains settles in these areas. These cool nights slow the metabolism of the vines and lengthen the growing season.
So, despite thousands of feet of elevation, we need to literally dig a little deeper to find the reason for the broad variability in the wines. In my other postings, I write about the alluvial soils of the region - where water from the Andes brought material into the valley. This occurred in a very nonuniform way. For example, in the southern region of San Carlos, there was a large glacier melt that brought rushing waters and flooded the region. The force of this water brought many large stones and rocks, especially closer to the mountains. As the force weakened further from the mouth of the alluvial cone, the water could only bring finer material. So, we find smaller rocks with more sand and silt. In the north, waters brought entirely different material to the area. In San Pablo, we can actually find fossilized remains of ancient marine life in sandy soils, while not far away in Gualtallary, we again find large deposits of rounded alluvial stones.
These varied soils have tremendous impact on the vine. Primary on this list is the water retention. With more available water, the vine has greater vigor in these desert conditions and produces lots of foliage and many bunches of grapes. This tends to lead to less concentration in the grapes and, similarly, less concentration in the finished wine. So, vineyards with large topsoils made of fine material like silt and sand hold water well. Vineyards with shallow topsoils and rocky sub-soils bleed water and the vine struggles to produce both a canopy and grapes. These two types of vineyards need to be managed differently, not just in terms of irrigation (an absolute necessity here in greater Mendoza), but in canopy management, fertilization and a host of other viticultural practices. All of these variables combine to define the vineyard and the grape ripening process and timing. Thus, each vineyard must be treated and harvested uniquely based upon the specifics of the soil.
Here's where things get really complicated. Even within a vineyard site, there is great homogeneity. So, armed with technology like electromagnetic conductivity testing, the Zuccardis have painstakingly set about to map each vineyard and break them into smaller parcels - or poligonos.
Once the above analysis is compiled and overlaid with other data (soil type and water retention are only two of many variables) a vineyard map is born and the poligonos are mapped in the vineyard (bottom right). This serves as the guide for the agronomist for some level of uniformity from poligono to poligono. We spent hours in a the Finca Los Membrillos marking blocks with tape, so that each block could be analyzed and harvested accordingly (bottom left).
To illustrate the importance of soil type, I include four pictures (below) taken from the same vineyard with different soil types. Unfortunately, the owners of this site (unnamed) managed the vines uniformly. The red foliage vines show extreme water stress leading to a lack of vigor (or any productivity) compounded by a slow late season metabolism.
As a result of mismanagement and uniform harvesting, the winemaker for the above vineyard will have grapes of varying ripeness and great diversity in terms of sugar content, acidity, polyphenolic development, etc. For the Zuccardi's, precise and controlled harvest scheduling, done poligono to poligono, is paramount to not only grape quality and uniformity, but this discrete and exact timing allows them to harvest without over-ripeness for a transparent, place-expressive grape like Malbec to more clearly tell its story. For a vineyard planted 40 years ago like Finca Los Membrillo, this requires a retro-fit, as evidenced from the poligon work I described. However, with new plantings in Gualtallary (10 hectares in 2016, 13 in 2018 and more coming), they are able to predetermine the blocks. It's exciting to see the interplay with variety and row orientation matched to soil type, aspect, elevation and exposure. An example of this is a hillside area with two exposures both planted to Chardonnay. One exposure is south facing (cooler) and the other is north facing (warmer). They have planted the north side with an east/west row orientation (cooler) and the south side with a north/south orientation (warmer). The slope of the hill moves east to west with the top of the hill having deep, sandy topsoils (more water retention & vigor), moving toward a rockier, shallower soil toward the east (less water retention and vigor). So, they have subdivided the polygons into two for each exposure and within each exposure subdivided further into three for the soil type, leaving 6 polygons to manage independently. As a result, the Zuccardi's have six uniquely expressive blocks of Chardonnay grapes with which to more precisely build a complex and balanced wine. In the not-too-distant future, look for a second Fósil Chardonnay from this region.
With all this specificity, each poligono the Zuccardi’s are planting in the high potential area of Gualtallary averages only half a hectare. Therefore, vineyard management will be a complex, time consuming labor of love, but should push quality levels for Argentine wine to new heights.