Rocks and Soil
Rocks and soil , in interaction with all subsystems, play an essential role in the existence of life on Earth. Rock fragments removed by erosion can be transported and enriched with organic matter, giving rise to soil. The constituents of soil are:
• mineral matter: made up of small rock fragments and mineral salts (46%);
• organic matter: in the form of humus, remains of leaves, branches, trunks and remains of decomposing animals (4%);
• water (25%) and air (25%): which occupy the spaces between soil particles.
Soil is a substrate for the fixation and growth of plants, which extract water and mineral salts from it. It is also responsible for the recycling of organic waste and the storage of nutrients. Soil filters and controls the flow of water that feeds underground reservoirs. Finally, soil is the habitat of numerous living beings... Did you know?