Characteristics of Chalk Soil
Last week, I was prepping for a staff training at Dinner by Heston Blumenthal at the Mandarin Oriental Hotel, doing a dry run in front of the mirror, as one does. It wasn’t just an excuse for some ‘mirror-time’, I do it because it pays to be polished as these prestigious restaurants have huge sommelier teams, all with varying levels of knowledge.
As I was talking at my reflection, it suddenly occurred to me how much I readily bandy about the term, “our vines are planted on chalk” to anyone who will listen, not fully understanding its significance and what it brings to sparkling wine. It plays a leading role on our labels, our marketing material, heck, we even had a large chalk display at our launch to illustrate how closely tied to chalk we are at Rathfinny. So, I started to do my research, partly to cover myself in case of any in-depth questions, but mainly as my interest had been piqued.
Turns out, it’s a pretty niche subject, and not a huge amount is readily available online. However, thanks to Margaret Rand’s 2015 piece in the World of Fine Wine Magazine, entitled “Chalk Talk; The Geology of English Sparkling Wine”, I was able to get a light schooling on what one of Rathfinny’s most prized assets brings to the table.
Full disclosure, I am about to massively precis, and possibly butcher, one or two elements of Margaret’s well-researched and vibrantly-written piece, an exhaustive article which explores whether the parts of England that share the same chalk as Champagne have just cause to celebrate the fact. Interestingly, it also covers the wider question of whether geology has an impact on a wine’s flavour.
Diving right in, one of chalk’s key super-powers, as Margaret Points out, is how it handles water, with one cubic meter holding 660 litres of water. My simple brain then asked the question, what’s the use of retaining water in a country that’s not short of moisture? Well, It’s the slow-draining property of chalk that’s the clincher, along with its strong “capillary action”. Obviously. “Capillary Action” is the force that allows soil to retain moisture and regulate its movement, in the same way porous materials like sponges soak up and hold liquid. It’s a phenomenon that allows water to move upwards or sideways within chalk’s micropores, against the force of gravity.
So, chalk does its best to hang onto water, forcing the vine to fight for it, which in turn develops a strong capillary action of its own. This push-pull situation going on at 500mm below the ground means that the vine is effectively getting a work-out, so you are allegedly left with fitter vines. Vines also love chalk because it’s rarely saturated and has good heat-storage properties, allowing it to absorb and store heat in the summer and restore it during the winter months. Genuinely fascinating stuff, but does chalk actually do anything to the flavour?
There’s a school of thought that chalk impacts the flavour perception of a wine’s acidity and how it evolves on the palate. Instead of being a menacing presence on the finish, some maintain that the acidity is more balanced from vines grown on chalk, evenly spread from the start of your first sip through to the back of your palate, giving the perception of less acidity. Compare this to greensand-grown grapes for example, a layer under the chalk that’s visible once the chalk has eroded, which is said to give more of a thwack of fruit on the palate.
All soils have their own particular pros and cons, green sandstone is well-drained, stony soils act as light reflectors but are uncompromising on machinery, clay retains nutrients, but takes longer to warm up and requires a good slope to improve drainage, pure chalk can require the addition of iron to avoid ‘chlorosis’, but as we’ve now established, gives the vine a mean capillary-action.
The true answer is that there’s world-beating sparkling wine coming from multiple areas around the country, not all produced from grapes grown on chalk. Clearly weather, viticulture, vinification and a hundred other factors go into making sparkling wine, famous for being one of the most technically tricky styles to produce. So, we should really be proud of the impact we’re starting to make on the world stage as a wine producing country, it’s an exciting time to be a part of the industry.
All that being said, at Rathfinny we do prize our chalk soil highly, and scientifically-based or not, feel it adds a unique dimension to our sparkling wines and consider it a major tenet of our identity. This is what I explained to the sommeliers at Dinner during my staff training last week, who kindly gave me a round of applause as I left, something you don’t get from presenting to a mirror.