In protected vegetable systems of the Mediterranean area, having bare soil for several weeks in late summer, post cash crop harvest, may induce soil degradation. Providing a soil cover in any period is key to preserve the soil's biological activity and maintain good agronomic conditions (e.g. soil structure) for the following crops.
A mixture of Sudan sorghum (Sorghum drummondii), buckwheat (Fagopyrum esculentum) and fodder pea (Pisum sativum subsp. Arvense) can be used as a cover crop at the end of summer under plastic greenhouse systems in the South of France. These species all grow fast and so provide a suitable cover crop in a few weeks. The higher the biomass production the better the crop is at delivering expected benefits.
This cover crop mixture provides biomass which is crushed and incorporated into the soil. Benefits include improved organic matter and soil structure, reduced risk of nitrogen leaching (the C/N ratio of the cover crop ranges from 10 to 40) and improved weed, pest and disease management. Cover crop mixture botanical families should differ from that of the vegetables to increase rotation diversity and contribute to the management of soilborne pathogens.