The exquisite sloping hillsides of Italy鈥檚 north-eastern wine region are where some of the world鈥檚 best prosecco is made. But a big problem is fermenting at the heart of this stunning place. Soil in the vineyards appears to be washing away at an enormous rate.
In the traditional centre of prosecco production, between the towns of Valdobbiadene and Conegliano, a new analysis estimates that 400,000 tonnes of soil is lost every year in the vineyards. The region produces 90 million bottles of prosecco annually, meaning that 4.4 kilograms of soil is lost for every bottle of fizz.
鈥淚 find myself in disbelief,鈥� says , a plant scientist at Hadlow College, who was not involved with the study. 鈥淚t鈥檚 more soil than the physical volume of the bottle.鈥�
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To come up with the estimate, the team factored in data on rainfall, the type of soil in the region and what kind of soil cover, if any, is available in the vineyards.
The vineyards have less vegetation growing through the soil, so rain can wash it away more easily. It鈥檚 a concern because over time large areas of hillside can be removed and, on shorter time-scales, the health of the soil can be affected detrimentally.
In the region the team studied, prosecco must abide by strict quality controls and is marked 鈥淒OCG鈥� on the label. Although erosion occurs across the DOCG area, the research suggests that vineyards are responsible for nearly three quarters of the total loss 鈥� even though they only cover a third of the land.
Based on an , the prosecco DOCG area鈥檚 erosion problem is roughly 40 times greater than the tolerable limit for the continent.
Prosecco bubble
Prosecco has boomed in popularity in recent years and production across Italy has consequently increased apace. Wine-makers in the other, larger prosecco-making region, known as the 鈥淒OC鈥� area, are said to be aiming for an annual production target of , nearly double the amount produced last year.
The researchers suggest that the erosion could be halved by allowing grass to grow between rows of vines, which would protect the soil beneath from rainfall. However, a consortium representing DOCG prosecco producers says this is 鈥渁lready a common management practice鈥�. It also disputes the findings, which have not yet been peer-reviewed.
鈥淭hese soil erosion estimates are, in our view, inaccurate,鈥� said a representative for the consortium in an email. 鈥淢anaging erosion is a primary interest of the winegrower.鈥�
Mazzey says the methods for modelling soil loss are relatively conservative. However, she points out that calculating the volume of soil removed rather than the mass may ultimately be more informative, since the bulk density of soil varies greatly depending on composition and wetness.
The mitigation proposals listed in the paper are worthy ones, says Chris Foss, head of wine at Plumpton College. He also suggests planting hedgerows and switching to horizontal terraces instead of the sloping vineyards in use today.
鈥淭here is already far too much soil loss on a global scale due to poor agricultural practices,鈥� he says. 鈥淭he wine industry should definitely not be adding to it.鈥�
Reference:听bioRxiv,
