In a natural ecosystem such as the forest, the soil is never disturbed and it is permanently protected by a very diversified plant cover, which creates favorable conditions for a strong biological activity (humidity, aeration, temperature, nutritive substrate, etc.). ).
Multiple plants and organisms from the soil live in interactions, ensure a high production of biomass and fulfill various ecosystemic functions such as:
the production of organic matter through photosynthesis, out of water and carbon dioxide;
soil protection and reduction of runoff by permanent vegetation cover;
nutrient and water recycling through deep roots;
the fixation of atmospheric nitrogen by plant-associated bacteria (in the nodules of legume roots or in the rhizosphere);
mineralization and solubilization of nutrients by living organisms ensuring a regular supply of plants;
soil enrichment in stable organic matter and carbon sequestration;
aeration of the soil by powerful root systems;
regulation of soil temperature;
the whole process of pedogenesis...
One may sow a mono-specific cover of legume (vetch, clover, alfalfa) or a mixture (legumes + phacelia, oats, ...) in which commercial crops will be sown with specific material. Canopy sowing can be done before the harvest of the previous crop (relay insertion), at the harvest of the previous crop or during interculture, at the same time as the sowing of the commercial crop or during commercial cultivation (permanent cover soil and multi-annual cover). This cover will be destroyed in the commercial crop by frost / herbicide or maintained until sowing of the next crop or beyond. Canopy can also be a commercial crop left in place after harvest (eg, seedling under alfalfa cover).
Beyond the agronomic benefits, the effects on a decrease in aquatic pollution and in favor of biodiversity are the most notorious.