Soil is the fragile, friable layer of the earth’s crust that covers the continents, between the surface and the bedrock. It is formed by mineral particles, organic matter, water, air and living organisms. It is the interface between earth, air and water and hosts most of the biosphere.
Soil provides us with food, biomass and raw materials, serves as a platform for human activities, our landscape and our heritage and plays a central role as a habitat and gene pool. It stores, filters and transforms substances such as water, nutrients and carbon.
Soil is a key, largely non-renewable and very complex natural resource and yet it is increasingly damaged by certain human practices.
Here are some key facts about soil
1. Soil makes up the outermost layer of our planet and is formed from rocks and decaying plants and animals.
2. Soil has varying amounts of organic matter (resulting from the decomposition of living organisms), minerals and nutrients.
3. It helps clean the water we drink and the air that we breathe — for free!
4. An average soil sample is 45 % minerals, 25 % water, 25 % air and 5 % organic matter. Different-sized mineral particles, such as sand, silt and clay, give soil its texture.
5. Topsoil is the most productive soil layer.
6. Ten tonnes of topsoil spread evenly over a hectare is only as thick as a one Euro coin.
7. Natural processes can take more than 500 years to form two centimetres of topsoil.
8. In some cases, five tonnes of animal life can live in one hectare of soil.
9. Fungi and bacteria help break down organic matter in the soil.
10. Earthworms digest organic matter, recycle nutrients and make the surface soil richer.
11. Roots loosen the soil, allowing oxygen to penetrate. This benefits animals living in the soil. They also hold soil together and help prevent erosion.
12. A fully functioning soil reduces the risk of floods and protects underground water supplies by neutralising or filtering out potential pollutants and storing as much as 3 750 tonnes of water per hectare.
13. Soil scientists have identified over 10 000 different types of soil in Europe.
14. Soils worldwide contain 1 550 billion tonnes of organic carbon (to be compared with an atmospheric carbon pool of 760 billion tonnes and 560 billion tonnes of carbon in living organisms and plants).
15. Soil captures about 20 % of the world’s manmade carbon dioxide emissions.