A state of mind
It all started with the re-conquest of the Torméry hillside by René Girard-Madoux.
In 1947, he was 20 years old and he worked the soil of his vineyards with a pickaxe or with a Swiss plough and winch: Plumette. He applied several times a year (2 to 3 times) the Bordeaux mixture and the sublimated sulfur to fight against the diseases. (Mildew, black-rot, oïdium).
He was an organic farmer without knowing it, and then he experienced the advent of chemical weed killers and phytosanitary products, including Dithane M45, which helped eradicate black rot in Chignin.
He used to say: “The guy who invented the chemical weed killer, I’ll hang a medal on him”. Mechanical or manual weeding was no longer a chore, and the old vines regained their vigor because their roots recolonized the layer of soil that had been worked, which is the most fertile.
When I took over from my father in 1988, I continued as he taught me. It was necessary to destroy the grass that was competing too much with the vine, especially on the slopes where the soil is less rich.
With the hindsight of two decades of this agricultural practice and the harmful consequences on the environment with the pollution of the water tables and aquatic environments and my growing sensitivity for the defense of the environment, I decided to stop the chemical weed killers in 2008.
Chemical weeding was replaced by mechanical weeding. It was necessary to invest in a caterpillar and a plough equipped with hydraulic interceps to work the soil in full: the inter row and under the row. I even brought out the plough and the winch to work the vines that my father had not planted wide enough to allow the passage of the plough.
I remember my father’s anger when he saw me stop using chemical weed killers and bring out the winch. With utter incomprehension, he said, “If you had suffered as much as I have suffered pulling grass in the vineyards, you would never give up weed killers.”
After another decade of this practice, I realized that the fertility of my soil was decreasing in spite of the organic fertilization that I was doing every year, and that the frequent use of interceps was damaging the vines. And to show this, we have an unstoppable measurement criterion which is the rate of assimilable nitrogen in the musts.
For several years, both white and red musts have been deficient in assimilable nitrogen. This nitrogen is essential for the good progress of the alcoholic fermentation. It allows for the proper development and multiplication of yeasts that can ferment all the sugars without organoleptic deviation.
While trying to understand this phenomenon, I became interested in Agro-ecology and plant cover. This cultural practice consists in fertilizing and regenerating the soil by sowing plants (legumes, grasses, crucifers) in the inter-row at the beginning of autumn before or after the harvest, depending on the date.
These plants, chosen to decompact and improve the porosity of the soil, are in bloom just before the vine. The vine lives on its reserves stored in the old wood until it blooms and then it draws the nutrients it needs for its growth from the soil. This is why, at the time of their full bloom, these plants will be rolled with a special roller (faca) which will lay them down by pinching the stems and their growth will be stopped. This fresh biomass (about 2 kg/m²) will dry and by the action of micro-organisms (mushrooms, bacteria and others) will reconstitute the stock of organic matter. The biological life of the soil will mineralize this organic matter and the roots of the vine will be able to feed on these mineral elements.
The objective of this practice is to make the soil of the vineyard self-fertile and to stop the external inputs of organic fertilizers such as manure or compost (no more organic inputs in 2022).
The main principle of Agro-ecology is that the soil must always be covered, never bare and never worked. This works very well for the inter-row, I apply it, but I have not yet found the solution under the row that I continue to work.
These plant covers have other properties such as acidifying the soil, because in the environment close to their roots the PH is 4, which allows the release of some nutrients blocked by the high PH (8) of our clay-limestone soils. Because of their allelopathic properties, they prevent undesirable plants from growing.
I am not making this up, I got all this information by watching hours and hours of videos on www.verdeterreproduction.fr where I discovered the work of Gérard DUCERF, a botanist who is interested in bio-indicator plants.
According to his work, if we count all the spontaneous flora on a plot of land, noting each species and its surface area, we can deduce the nature, structure and composition of the soil on that plot. It is accepted in organic agriculture that spontaneous flora grows to rebalance the soil. In the future, we will be able to draw inspiration from spontaneous flora to better choose our plant cover.
It is still too early to draw conclusions on the improvement of the rate of assimilable nitrogen in the musts, but I persist in this way of cultivation, I believe in it because I observe an improvement of the biodiversity in my plots and I do not see the grass in general as a competitor any more but as an ally.