Several functions depend on biological activity: the transfer of nutrients from the soil to the plant, the dissolution of minerals from the source rock, the mineralization of organic matter, the stabilization of the soil structure by the synthesis of organic substances, the cohesion of aggregates and the formation of galleries for ventilate and create porosity. Biological activity has direct consequences on the physical and chemical properties of soils. Soils are home to more than a quarter of all living species on Earth. There are no less than 260 million individuals per m2 of soil, i.e. an overall mass equivalent to 12 adult cows per hectare. A diverse and diverse community of soil organisms working day and night in a remarkable coordinated effort to support life on Earth. In an area the size of a football field, soil organisms annually produce humus that can weigh as much as 25 cars.