Legumes, a family of plants popular in organic and Biodynamic winegrowing 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, p56).
Legumes as vineyard cover crops | Beans, clovers, medics, peas and vetches.
Examples | Common vetch.
Risks | Some wine-growers argue excessive use of legumes should be avoided for vines on sites which favour the development of bunch rots.
Helen Philbrick & Richard Gregg, Companion plants & how to use them (USA, 1966).