Soil Basics

Electron micrograph of a soil fungus

Soil is an amazing substance. A complex mix of minerals, air, water, and countless microorganisms, soils forms at the surface of land and comes in many types. Put another way, soil is the thin, outermost layer of Earth’s crust, and like our own skin, we can’t live without soil.

Why? Soil performs many critical functions in almost any terrestrial ecosystem, whether a farm, forest, prairie, or city.

  • Most of our food comes directly or indirectly from plants anchored in, and nourished by, soil
  • Soils modify the atmosphere by emitting and absorbing dust and gases, including carbon dioxide, methane, and water vapor
  • Soils provide habitat for soil organisms--mostly microscopic creatures that account for most of the life on Earth
  • Much of the water we drink and use every day has been filtered and purified by soil
  • Soils process and recycle nutrients, including carbon, so that living things can use them over and over again
  • Soils serve as the foundation for the construction of roadbeds, dams, and buildings

Like our skin, soil is easy to take for granted—and to damage.


Soil Scientists: Who We Are, What We Do

International Soil Judging first place Team USA on soil pit
September 23, 2015

To four budding soil scientists, soil is not just what’s underfoot. It’s a passion, and a key to future success.

May 01, 2015

Ed Landa has been captivated by soils since his undergrad days, but they’ve hardly been his sole fascination. His love of art, history, and...

Phil Small
March 19, 2015

As an art major at the University of California–Davis, consulting soil scientist Phil Small says he always dug clay much more than the...

January 09, 2015

This month, we profile retired USDA-ARS plant physiologist and research leader Betty Klepper, who was elected the first female Fellow of the Soil...