Bet you never even noticed it, except when you've been playing in it and your mom tells you to wash your hands. Do you know what we're talking about? Yeah, you've got it. Dirt. Plain old dirt. The stuff you get under your fingernails. Except we like to call it SOIL. Ever try to plant a forest without any soil?

Soil is made up of decomposed rock. Freezing, thawing, water, and chemicals in the rocks themselves, sloooowly break down the rock. How slowly? Get this. In the Boise National Forest, it takes about 700 years to create an inch of soil. The soil under your feet actually got its start almost 200 years before Columbus reached America!

Soils develop into distinct layers or what soil scientists call "horizons." Heat, cold, and water move rock pieces and soil particles into horizons. The bottom layer is rock. Soil near the surface is mixed with leaves, twigs and dead animals rotting on the forest floor. This horizon is the darkest (all that rotting stuff adds nutrients to the soil.) The layers in between are rocks in different stages of decomposition. How thick each horizon is depends on the type of rock, water, temperature, plants and time. Soil scientists use horizons to classify and map soils.

Soil is filled with life! True statement: in most places, there is more life below the ground than above it. Lots of bugs live in the soil of a conifer forest: spiders, mites, worms, nematodes, springtails, and a bunch more that you can only see with a microscope. There is a whole new world just under that first layer of soil.

Soil is a finite resource. Finite means it has an end. Humans need soil. Ever try to plant a garden without any soil? It's important that we protect and conserve the Earth's soil so we can grow food and trees. Soil Scientists study dirt to learn how we can better conserve it.

When the Talk Turns to Dirt, Here's What to Remember:

1. Soil is a finite resource.
2. Soil needs to be conserved.
3. Soil is a complex, living system that is always changing.