Synonym(s) : Natural fertility
Autofertility defines a soil able to preserve its own fertility, i.e. how easy it is for a plant to benefit, in sufficient quantity, through its roots and in the soil, from different factors of plant growth. A soil’s autofertility depends on its biological activity, impacting the physical and chemical self-fertility.
A physically self-fertilizing soil is a soil whose structure continuously guarantees a good establishment of the roots, in a significant volume of it, and good gas and water exchanges. These three elements are created and maintained by the soil biological activity (earthworms, roots, micro-organisms …). Similarly, a chemically self-fertilizing soil maintains, both in quantity and quality, the chemical resources which are needed for the plants. It is necessary that the soil has a sufficient quantity of organic matter for primary and secondary mineralizations, which are ensured by the activity of decomposer organisms followed by mineralizers. Hence, soil biological activity is a keystone feature of soil fertility.
Autofertility of soils is an objective of agroecology, in order to improve farms’ autonomy from inputs. With agricultural holdings, autofertility depends on several elements: on the one hand on closure of material flows, with exported elements returning to the soil (manure, compost, digestate…), and on the other hand the preservation of soil structure. The absence of any tillage now emerges as an important lever to promote soil autofertility, by avoiding any disturbance of biological activity. The ground surface is also of importance. A bare soil is impacted by the weather, which in turn affects its chemical and physical fertility (soil sealing, runoff, decline in mineral elements’ recycling …). In contrast, soils protected by crop residues and/or cover crops tend to preserve their fertility.