May: the green manure planted after the 2017 grape harvest is in full bloom (photos 1 and 2). Now is the time to shred them before they go to seed. We have been planting green manure post-harvest for the past 3 or 4 years with the aim of improving soil fertility.

Just to recap, green manure helps to:

• Structure and stabilise soils thanks to the mechanical action of the roots and the chemical action of microorganisms and root exudates,
• Promote biological life in the soil,
• Stock organic matter and carbon in the soil
• Add nutrients nitrogen (N), phosphorus (P), potassium (K), magnesium (Mg), sulphur (S) and calcium (Ca), as well as micronutrients

But this year, before destroying them, we also assessed their quality using the MERCI method developed by the Chamber of Agriculture: after isolating one square metre of green manure with a wooden frame, we cut all the plants within that area (photo 3). We then carefully sorted the different varieties sown (photos 4 and 5). Back in the workshop, we weighed all the gathered and sorted plants separately (photo 6).
We entered the weights into a spreadsheet that will enable us in future to measure the biomass and, above all, how much N, P and K – crucial for vine growth – are restored to the soil by the plant cover.