Agroecology and mycorrhizae

Agroecology and mycorrhizae: the new frontier of biological fertility

For decades, modern agriculture has considered deep soil cultivation—intense plowing, subsoiling, and tillage—essential practices for achieving high yields. Turning the soil meant “preparing” it, making it fertile, and controlling weeds. Today, however, agronomic and ecological research is increasingly demonstrating that this approach can have very negative effects on the biological life of the soil, particularly on the delicate relationship between plants and mycorrhizae.
Mycorrhizae are symbiotic associations between soil fungi and plant root systems. Through an underground network of microscopic filaments, fungi greatly extend the exploratory capacity of roots, allowing plants to better absorb water and nutrients from the soil. In return, they receive sugars produced by photosynthesis. This is an ancient cooperation, evolved over millions of years, which represents one of the foundations of the natural fertility of terrestrial ecosystems.
This biological network plays a fundamental role, especially in the absorption of water and nutrient-poor nutrients such as phosphorus, zinc, or copper. A well-mycorrhized plant generally tolerates drought better, utilizes available nutrients more efficiently, and develops greater resistance to environmental stress. Fungal hyphae act as a true extension of the root system, greatly increasing the contact surface with the soil.
Deep tillage, however, disrupts this balance. Every time the soil is turned, the fungal networks are broken and destroyed. It’s like demolishing a complex underground infrastructure that requires time and biological energy to rebuild. Furthermore, excessive soil movement alters microbiological habitats, accelerates the oxidation of organic matter, and progressively depletes soil biodiversity.
Added to this problem is another often overlooked aspect: the impact of chemical inputs and agricultural pollutants on soil microbial life. Intensive use of herbicides, fungicides, insecticides, and synthetic fertilizers can profoundly alter the soil’s biological balance. Many herbicides indirectly reduce mycorrhizal activity by eliminating the spontaneous plants that keep the fungal network alive throughout the year. Furthermore, some fungicides, while intended to control pathogens, can also affect beneficial fungi present in the soil, compromising the development of mycorrhizae.
Excessive chemical fertilization can also have negative effects. When the soil receives large amounts of readily available nutrients, especially phosphorus and nitrogen, plants tend to reduce their collaboration with mycorrhizal fungi because they no longer “perceive” the need to invest energy in the symbiosis. In the long term, this leads to progressive biological impoverishment of the soil and a growing dependence on external inputs.
Added to all this are the effects of agricultural and industrial pollution: accumulation of heavy metals, chemical residues, soil salinization, and water contamination can further compromise microbiological biodiversity and the functionality of mycorrhizal networks. The result is soil that is increasingly depleted of life and less capable of self-regulation.
The consequences for crops can be significant. Plants deprived of a healthy mycorrhizal symbiosis become less efficient at absorbing water and more vulnerable to water stress. In drought conditions, they tend to wilt more quickly and reduce their photosynthetic activity. Nutrient absorption also deteriorates: elements present in the soil can become less available simply because the plant has lost the biological network that allowed it to intercept them.
To compensate for this loss of efficiency, conventional agriculture has often increased the use of chemical fertilizers, irrigation, and mechanical energy. This has created a vicious cycle: the more the soil loses biological vitality, the greater its dependence on external inputs. However, this model is now showing all its limitations, especially in the face of the climate crisis, water scarcity, soil erosion, and rising energy costs.
It is in this context that agroecology proposes a profound shift in the agronomic vision. Soil is no longer considered a simple physical support to be worked and chemically corrected, but a living ecosystem made up of roots, microorganisms, fungi, insects, organic matter, water, and air. Fertility depends not only on the quantity of fertilizers applied, but on the quality of the biological relationships present in the soil.
According to agroecological principles, the farmer’s task should not be to “dominate” the soil through continuous tillage, but to foster the natural biological processes that sustain fertility. Reducing mechanical disturbance, limiting the use of pesticides and herbicides, keeping the soil constantly covered with vegetation or crop residues, increasing crop biodiversity, and restoring organic matter to the soil are practices that allow soil life to be regenerated and mycorrhizal networks to be rebuilt.
In this new perspective, fertility is no longer seen as a simple chemical problem, but as a biological and ecological property of the soil system. A soil rich in life is better able to retain water, store carbon, nourish plants, and withstand extreme weather events.
Mycorrhizae thus become the symbol of a new agronomy: an agriculture that no longer separates production and ecology, but recognizes that crop health depends directly on soil health. The agroecological transition certainly requires technical innovations, but above all a profound cultural shift: moving from an extractive and mechanical model to a regenerative model based on collaboration with nature’s living processes.

Guido Bissanti