IT’S more than five years since I last visited Olivier and Astrid Bonnafont at their Domaine Peyres Roses at Cahuzac-sur- Vère in the rolling hills north of Toulouse.

They have 15 hectares of land, seven-and-a-half of which are planted with vines, from which they craft the best wines of Gaillac.

Olivier’s passion for sustainability and biodiversity was apparent from the start. He never intended that the entire farm should be covered only with vines and set about planting many other things including truffle oaks, a remarkable gesture of long-term commitment to the future of the site.

In 2008 he converted the estate to a full organic regime. I was fascinated to discover what difference it has made and to re-taste his wine.

There are two immediately noticeable changes. When I first visited, grass and other plants grew between the two rows, which is fairly standard practice in organic viticulture, but the rows have now been neatly hoed to clear the vegetation.

Grass is often used as a cover crop to provide competition for the vines to encourage them to root more deeply in search of water. Vines also produce better fruit if they are slightly stressed.

But, as Olivier explained, “water has become ever more precious here and we found that the grass was taking too much of it.”

He estimates that average annual rainfall has fallen from the 680mm when they arrived 12 years ago to around 500mm now. Drought conditions were especially severe in 2011, when it was so dry that many of the grapes failed to swell properly. The thin topsoil that barely covers the local limestone is soon parched.

The removal of the cover crop also has the unfortunate consequence of removing one of the prime refuges for friendly insects that help to provide a balanced eco-system for the vineyard.

To compensate, Olivier has planted more patches of wild flowers around the vineyards. Flowers are never more than 50 metres away from any vine.

Olivier also believes that the essential oils given out by them help to provide a beneficial environment for the vines. It is also possible that as the stomata (pores) on the vine leaves open and shut as part of the process of transpiration, some of the heady aromas are absorbed by the plant and eventually find their way into the wine, as growers in New Zealand’s Central Otago, whose vines are surrounded by wild thyme, have suggested.

The other big change is that in a field to one side, Pompon, a hefty draft horse, can be seen grazing peacefully. Olivier was very upset when in their early years at Peyres Roses, as they struggled to get established, he was forced to sell his much-loved horse.

Pompon is not quite the handsome Percheron, the breed that former show-jumper Olivier would love to own and ride, but she works hard for her living by pulling a hoe between the vines.

It is important to Olivier to have large animals on the farm. They are, he feels, an integral part of the biodiversity needed to ensure that everything is healthy and in balance. Horse manure is a wonderful fertiliser and ducks wandering amongst the vines help to control the population of snails; but Astrid has vetoed his proposal to introduce sheep as well. She says they would eat her roses.

Organic viticulture is hard work and time consuming for horses and humans. Olivier has not calculated how many extra hours it demands of his time, but he is happy that the organic treatments he uses are cheap. His annual bill is no more than €100 Euro, much less than that faced by organic growers in damper regions where more frequent treatments are necessary. Nevertheless, the need to be profitable is such that he feels that he cannot afford official organic or biodynamic certification. “I would have to put up my prices and I’m not willing to do that,” he told me.

Astrid is in charge of marketing what they make. Most of it is sold at the cellar door to individual clients, which works well for the Bonnafont family.

Although it can be time-consuming, it brings more revenue and avoids the hefty discounts demanded by big supermarkets and importers.

And five years on, despite the problems with small crops in 2009 and 2011, Astrid and Olivier are convinced that they were right to go organic.

Their wine, made with just the minimum of added sulphur, really does seem to taste better with clear, bright fruit flavours that seem to express the essence of the local varieties, typified by their simplest dry white 2011 – an apricot-scented blend of Len de l’El, Mauzac and Muscadelle: as fresh and refreshing a wine as you could hope to find, with a lovely savoury minerality.

To buy their wine, you too will have to beat a track to Gaillac, but The Wine Society has persuaded another fine producer of organic wine in the region, the Domaine de Pialentou, to part with some stock, including my wine of the week, which is wonderful value for money.