Legumes, a family of plants popular in organic and Biodynamic wine growing and other forms of organic farming as a cover crop, specifically for their ability to grow root nodules which attract beneficial bacteria capable of ‘fixing’ nitrogen assimilated by the cover crop plant from the atmosphere into the soil. These nitrogenous compounds are in the form of ammonium. Legumes produce intricate root systems which also improve soil structure (Philbrick & Gregg: 1966, p.56).

Legumes used as vineyard cover crops include beans such as Broad beans, vetches such as Common vetch, as well as clovers, medics, and peas.

Risks: Some wine-growers argue excessive use of legumes should be avoided for vines on sites which favour the development of bunch rots.

Bibliography

Helen Philbrick & Richard Gregg, Companion plants & how to use them (USA, 1966).