At Château Cazebonne, our commitment to soil health goes far beyond theory. We use practical, telling methods to assess their vitality on a daily basis. Among these, one of the most surprising and simplest is undoubtedly the "cotton underwear test". Far from being just an amusing anecdote, this practical experiment is a powerful visual indicator of the biological activity teeming beneath our feet. It involves nothing less than burying a pair of 100% natural cotton briefs in a vineyard parcel, and then digging them up a few weeks or months later. If the underwear is largely decomposed, consumed by microbial life and soil microorganisms, it is undeniable proof of a thriving ecosystem—a testament to the richness of the soil fauna and microflora.

The underwear test is not a recent invention, but it has gained popularity in recent years as an educational tool to raise awareness of the importance of living soils. In viticulture, it offers a very direct visual demonstration of the impact of farming practices on subterranean biodiversity. At Château Cazebonne, it fits seamlessly into our philosophy of agroecology in viticulture, where every action aims to reinforce natural balances.

A visual indicator of soil biology

Why cotton underwear? Because it is made of natural fibres, and therefore entirely biodegradable. In a healthy, living soil, bacteria, fungi, earthworms and other decomposers work to break down organic matter into humus—a life cycle essential to the fertility and nutrition of the vine. The extent of the fabric's decomposition thus tells us about the efficiency of these tireless "soil workers" and the intensity of the biological life present. Intact underwear suggests a depleted, compacted soil lacking biodiversity, whereas a nearly skeletal remnant attests to a dynamic terroir where organic matter actively circulates and transforms—a guarantee of vitality for our vines and typicity for our wines. This simple test complements our more in-depth analyses, giving us an intuitive, rapid understanding of the condition of our parcels.

The rate of decomposition depends on many factors, such as temperature, moisture and, of course, microbial activity. Underwear buried in a rich, well-aerated soil will break down much faster than in poor, compacted ground. This provides us with an engaging, tangible way to monitor the progress of our practices and refine our understanding of earthworms and other mysterious subterranean inhabitants.

Beyond the underwear test

The underwear test is just one example of the many approaches we favour at Château Cazebonne to observe, understand and support soil life. This viticultural approach is part of a broader philosophy: restoring natural balance and reviving a forgotten wine heritage. Our work replanting historic Bordeaux grape varieties, such as Castets, Mancin or Saint-Macaire—whose history and characteristics are so vividly described by Jean-Baptiste Duquesne in his book "Bordeaux, une histoire de cépages"—is directly linked to this endeavour. Giving new life to these forgotten varieties also means providing them with the finest terroirs—vibrant soils that reveal all their typicity and aromatic complexity. This ambitious project is made possible thanks to the passion and support of our many wine enthusiasts who, by embracing our wines, encourage us along this demanding yet deeply rewarding path. To deepen your knowledge of our viticultural heritage and the fascinating history of these grape varieties, you can download a digital version of the book "Bordeaux, une histoire de cépages", published by Éditions BBD and written by Jean-Baptiste Duquesne, by clicking here. Test your knowledge of oenology and our estate with our wine quizzes, and discover our full range of cuvées to accompany your moments of sharing in the Cazebonne shop.