Earth

An environment full of life

Even though not much is known about soil organisms, it is certain that soil is not an inert and sterile environment but, on the contrary, it is a dynamic one overflowing with life. The majority of the organisms live within the first metre in depth and, in general, the biological spaces they occupy and their biological activities are on a very small scale. The growth of cultivated plants, for example, depends on the way in which the solid particles of the soil are arranged to allow the formation of spaces with a diameter of about 0.2 mm. Moreover, these plants depend on the activity of micro-organisms that are about 1 µm (1,000 µm = 1 mm) in size, to contribute nutrient substances such as nitrates. Soil is a resource of great environmental value, and at the same time, it is also an ecological system that recovers with difficulty each time its health is harmed by pollution produced by Man. It carries out an extraordinary activity of preservation of ecological equilibriums and plays a crucial role in the protection of human health. A proof is its complex activity as a biological and chemical filter, capable of slowing down and limiting dangerous chemical pollutants that, penetrating from the more superficial layers towards the deeper ones, could reach the layer with the water that we drink. As far as the inorganic chemical composition and the structure of soil are concerned the reader can refer to these topics discussed in the section ‘Earth’.