How does Soil affect a Wine – Chardonnay?
SAME ESTATE, SAME CULTIVAR, SAME VINE-GROWING, SAME WINEMAKING, SAME VINTAGE – DIFFERENT SOILS
Thursday 25 May 2020
Dr Peter Rating – Experience: 5/5
Dr Peter Rating – Wine: 4.5/5
A month ago, I ‘Tasted Live’ two Sauvignons Blanc from Lomond estate. The wines were identical except that one was made with grapes from clay and the other from sandy loam. It made for a fascinating tasting and to explore whether theory matched practice (read more here) and one worth repeating. The opportunity arose with two Chardonnay from De Wetshof. Both wines were 4* Platter’s rated, of the same vintage (2019), made with grapes of similar age, contained 13.5% alcohol and vinified in the same way: de-stemmed grapes, fermented in stainless steel tanks, unwooded and matured on the lees for 6 months before bottling.
De Wetshof lies in the Robertson Valley. It is the oldest estate in the Valley. Danie De Westhof pioneered the growing of noble grape varieties in 1972, first Chardonnay and then Sauvignon Blanc. Three generations of winemakers later and with 180 hectares under vine, De Wetshof produces mostly white wine (90%). The estate has a range of rocky slate and clay soils with limestone outcrops.
Each soil type brings a different character to a wine. Limestone contains beneficial nutrients to produce better and sweeter grapes. It remains moist in dry weather and has good drainage. It can lead to iron deficiency which is overcome by frequent fertiliser application. The alkalinity in the soil promotes acidity to make zesty wines. Clay retains even more moisture than limestone which it releases throughout the dry summer months. The extra moisture brings a cool soil to slow ripening. The resultant wines are rounder, bolder, more generous and with more structure and colour from deeper extraction. Slate is metamorphosed clay that has been compressed under heat and pressure. It is low in organic matter so does not retain water. Therefore, slate soils warm quickly and retain heat. Broken rocks on the surface shade the roots from the sun and reflect the heat onto the vines, which make them good in cool climate regions. The resultant wines contain higher levels of alcohol, leaner and more mineral in character.
The popular Limestone Hill Chardonnay is made with grapes that are grown close to the River Breede. This has heavy clay soils that are rich in limestone. The Bon Vallon wine comes from vineyards in Bonnievale (hence the name) that contain broken rock with slate. The expectation therefore is that the Limestone Hill wine will show more structure and fullness, with deeper colour and more tropical fruits than the Bob Vallon Chardonnay. The latter ought to show a more steely and mineral character. The Tasting Notes describe aromas/flavours of ‘grapefruit and nuts’ and ‘citrus, wildflowers and grilled nuts, with a nuanced minerality on the aftertaste’ for the Limestone Hill and Bon Vallon wine, respectively.
The proof of the wine is in the drinking, so to speak, and so I poured equal amounts of each into a bowl-shaped wine glass, ideal for Chardonnay. With both wines being unoaked and with the same winemaking, there was predictably little colour difference. I tested the Nose on both wines first without swirling as this can help to detect minor variation. The Limestone Hill (clay) showed slightly more intensity of aroma than the Bon Vallon (slate). With swirling, the Limestone Hill revealed aromas of baked Granny Smith apple, melon, kiwi fruit and green pineapple. This compared with the Bon Vallon that was more citrus in character, showing less tropical fruit notes and more lemon and lime citrus.
The Chardonnay were beautifully balanced on the palate – between fresh fruits, well-integrated acidity, and the medium alcohol – to make two excellent wines. There was a distinct difference on the Palate between them. The warmer tropical fruits of the clay-based Limestone Hill followed through on the Palate that was fuller, weightier and with more structure in the mouth. In contrast, the Bon Vallon showed a livelier and fresher character with a cleaner mouthfeel and more mineral character due to the rocky slate soils.
The tasting fascinated as expected. It was intriguing that the practice of tasting matched the theory as forecast. Whilst the clay soils were cooler than those of the rocky slate, this had the effect of slowing down ripening to allow a fuller structured and rounder wine with more sugar development and hence a warmer fruit profile. The tasting proved, if proof ever needed, the extent to which fine wines are made in the vineyard, together with the vital importance of terroir.
2019 De Wetshof Limestone Hill Chardonnay – R102
2019 De Wetshof Bon Vallon Chardonnay – R142