Kids
Dirt or Soil? Soil or Dirt?
What’s the difference between soil and dirt? Dirt is what you find under your fingernails or you sweep off the kitchen floor. Soil is what you find under your feet. Think of soil as a thin living skin that covers the land. It goes down into the ground just a short way. Even the most fertile topsoil is only a foot or so deep. Soil is made up of more than just pieces of rock. It includes all the living things and the materials they make or change.
Believe it or not, not all soils are the same. Soils can be as diverse as the animals and plants above it. In fact, if we were to dig straight down in the soil like a mole we would see distinct layers in the soil called horizons. All of these layers form a soil profile.
Ground level: Plants grow and animals live here. A thick cover of plants can keep the soil cool and keep it from drying out. Decomposers (bugs, bacteria, and fungi) break down dead plants and animals. This is natures way of recycling.
Topsoil: Plants grow and animals live on top of the soil. This is sometimes called the organic layer. A thick cover of plants can keep the soil cool and keep it from drying out. Once again we find decomposers who do the job of recycling the dead plants and animals.
Subsoil: This is a mix of mineral particles and some humus near the top. Subsoil is very low in organic matter (everything that came from plants and animals) compared to the topsoil. This is the layer where most of the soil's nutrients are found. Deep plant roots come here looking for water. Clays and minerals released up above often stick here as water drains down.
Weathered parent material: This horizon can be very deep. There's no organic matter here at all. We're out of reach of all living and dead organisms down here. It's all rock particles, full of minerals. At one time the soil profile all the way up to the surface looked like this. Over time physical weathering broke this parent material up into smaller and smaller bits. Don't be fooled! This layer may contain rock particles that are different from the bedrock below. A river or a glacier might have brought it from somewhere else.
Bedrock: We finally found solid rock! The bedrock formed before the soil above it. It will wait here until erosion or an earthquake exposes it to the surface. Then some of it will be weathered to become the next batch of parent material. The soil-making process will start all over again.
Websites
Wilbur The Soil Wizard: Soil Biological Communities Fun facts, games, and lots of information about soil.
www.blm.gov/nstc/soil/Kids/
Science Made Easy Get fun science projects & great experiments using household materials.
www.sciencemadesimple.com
Do Science This weird and wacky page has experiments for you to try if you ever go eat in a restaurant to pass away the time before your food finally arrives!
www.doscience.com/index.html
The Science Club has hundreds of experiments for you to try, ranging from simple to difficult, with lots of ideas for science projects. Check out how to make your own DistgustoScope!
scienceclub.org/
Science Clips from the BBC (British Broadcasting Corporation) has different activities for different ages, can you find something for you.
www.bbc.co.uk/schools/scienceclips/index_flash.shtml
Underground Adventure Transmorgify down to the size of a spider and check out life underground.
www.fieldmuseum.org/ua/
MooMilk A fun and educational website about cows and milk with facts, contests, games and recipes. Join the herd! www.moomilk.com/
So you want to know about Bats? Facts about bats and bat conservation from the Organization for Bat Conservation http://www.batconservation.org/content/Kidsandbats.html
DragonflyTV Games, experiments, and activites from DragonflyTV
pbskids.org/dragonflytv/index.html
Games
Go on a Soil Safari in this great game from Discovery.
What's your soil IQ? Try this and more games.
Wildlife games at this BBC website
Lots of games at the National Geographic site