The ability of soils to provide essential elements (mainly nitrogen, phosphorus and potassium) for plant growth through the action of living organisms (animals, insects, fungi, parasites) with complex interrelationships that feed on plant or animal debris. All these organisms contribute to the degradation of organic matter, which leads to the release of nutrients necessary for the plant. A fraction of the organic matter, which is easily degraded, contributes to soil fertility by feeding the microbial biomass, which in turn contributes to plant nutrition in terms of nitrogen, phosphorus, etc. Another fraction, known as “stable”, plays a role in structuring the soil. The balance of the ratio between degradation and stabilisation of organic matter determines the biological fertility of the soil.
This biological fertility favours the availability of water thanks to the creation of micropores that retain water in the soil. The emblematic organisms of this biological activity are earthworms whose presence is a bio-indicator of soil fertility. They also contribute to the stability of the soil structure and facilitate access to water and nutrients for plants.
In addition, soil fertility contributes to plant protection, i.e. a fertile soil is a soil with a high diversity of living organisms that can help in the biological regulation of the agricultural ecosystem.
The biological activity of the soil influences the structure of the soil and is encouraged by practices such as crop rotation or the establishment of vegetation cover that limits erosion in winter. In agro-ecology, conservation practices are based on simplifying soil work and make it possible to preserve and promote this biological fertility with a view to sustainable management of soil organic matter.
Source: dicoagroecologique.fr