Every land can be considered a living organism formed over thousands of years and still being transformed today. It is formed by the disintegration of the parent rock and is therefore made up mainly of inorganic mineral substances and, to a lesser extent, of decomposed plant and animal residues which constitute the organic component. The soil has several layers, the first layer, a few centimeters high, is formed by covering and decomposing organic material (leaves, dry branches, fragments of bark, grassy hollows, etc.); everything is degraded and slowly transformed into nutrients for plants (humus) from the set of micro-organisms present in the soil. Therefore, most of the vital processes take place in the superficial layer, the most aerated. Immediately below there is a layer of thickness ranging from a few centimeters up to 50-60 (in the most fertile soils), rich in already decomposed organic substances and microbial life; it is here that the roots find most of nourishment. At greater depth, finally, there is a mineral layer, progressively poorer than life, which reaches the bottom, where the original rock formations are found.
Life in the ground.
Healthy soil is a living soil that hosts a multitude of living beings from the plant and animal world. From the simplest and most microscopic organisms – such as bacteria, algae, fungi and protozoa – to the more evolved ones such as nematodes, worms, earthworms and insects that live in soil and soil. They are decomposing organisms, or predators of decomposers, make the soil fertile, because they transform complex organic substances (branches, leaves, excrements, dead or alive organisms …) into simpler compounds, assimilable by plants, thus play an important role in recycling of all nutritive elements. A second important function is to give the soil a micro-glomerular structure, consisting of organic particles combined with mineral particles that allow the passage of air, and the drainage of excess water between the micro and macro pores. The third important function is to protect the rhizosphere, thanks to a strong sense of territoriality, occupy the whole space, defend it from predators and pests of plant roots and induce the plant to produce a group of substances that are not very favorable.