Among the three fundamental elements of life – water, air, and soil – the latter often remains the least explored. Yet, it constitutes an essential ecosystem where life flourishes remarkably.
Water
Water, an indispensable element for life, serves as the vehicle for nutrients to reach cells. The water molecule, composed of two hydrogen atoms and one oxygen atom, exhibits a unique polarity that enables it to transport both cations (potassium, magnesium, calcium) and anions (nitrate, phosphate, sulfate). Its remarkable resistance to disappearance is evidenced by its boiling point of approximately 100°C.
Air
Composed mainly of nitrogen, air is a robust medium, formed by nuclear bonds that are difficult to break. Pollution of air and water requires a considerable intensity of abuse to definitively break the molecules. In the early 20th century, the nitrogen molecule was broken to create nitrates, notably used in the manufacture of explosives.
Soil
Unlike air and water, soil is an organic-mineral complex, extremely fragile. It consists of organic matter, such as humus, and mineral matter, like clays. These components are held together by fragile electrical bonds.
Long neglected, the science of soil dates back to the 17th century with the work of Olivier de Serres. However, it is in the 19th century that the true understanding of soil emerges.
Over the past 7,000 years, humanity has cultivated the land, leading to the destruction of vast expanses. In the 19th century alone, one billion hectares were lost, and another billion since then. This degradation, resulting from abusive and unsustainable use, has caused catastrophic soil erosion. Soil harbors three realms: animal, vegetable, and fungal. Together, they create a fertile environment, enabling the absorption of nutrients by plants. The quality of the soil directly influences the terroir, giving each crop its specificity.
The creation of humus, resulting from the decomposition of leaves by epigeic fauna and fungi, enriches the soil and promotes its permeability. Horizontal roots then absorb mineral elements, while vertical roots transform the parent rock into clay, thus contributing to soil formation. Earthworms play a crucial role in the creation and structuring of the soil. Their action oxygenates the soil and promotes the solubilization of minerals, essential for plant growth. However, their population has significantly decreased due to the intensive use of pesticides and chemicals.
To better understand this theory, I yield the floor to the foremost specialist in soil microbiology, none other than Claude Bourguignon.