April 19

erosion. Photo Credit: Paul Glazzard [CC BY-SA 2.0 (http://creativecommons.org/licenses/by-sa/2.0)], via Wikimedia Commons. Photo Credit: Paul Glazzard [CC BY-SA 2.0 (http://creativecommons.org/licenses/by-sa/2.0)], via Wikimedia Commons.

Science Fact

Soil: A Nearly Non-Renewable Resource

Soil is a  thin layer of non-renewable natural resource separating our atmosphere from Earth's crust. It is composed of organic matter, inorganic mineral particles, air, water, and microscopic living organisms. Man-made materials can also break down into soil, becoming part of it.

It takes 2,000 years to accumulate 4 inches of fertile topsoil, yet erosion and land misuse leads to a loss of an estimated 24 billion tons or 1.2 million hectares each year.

There are a variety of ways to classify soils, but the World Reference Base for Soil Resources offers these classifications:

  • Soils with thick organic layers
  • Soils showing strong human influence
  • Soils with limitations to root growth due to permafrost or rock
  • Soils influenced by water
  • Soils distinguished by their special iron and aluminium chemistry
  • Soils with a dark and humus rich topsoil
  • Soils with accumulation of soluble salts
  • Soils with a subsoil enriched in clay
  • Soils with little or no development
  • Soils that are permanently flooded

Soils help plants grow, by bringing nutrients and water to their roots. They contribute to climate regulation by storing carbon and by helping to regulate water and atmospheric gases. They also stabilize building foundations, as well as making up part of the water cycle and the food web. Finally, they support the planet's biodiversity, serving as the home for a quarter of the world's organisms, including microorganisms such as bacteria, fungi, and protozoans, as well as thousands of insects, mites and worms.

Check out these Science NetLinks resources relating to soil and what comes from it:

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