Layers of Soil
If you could cut into the ground like slicing a cake, you would see layers! The top layer is called topsoil. It is dark, rich, and full of life. This is where plant roots grow and where most soil creatures live. Topsoil is only a few inches to a foot deep, but it took thousands of years to form.
Below topsoil is the subsoil. It is lighter in color and has fewer living things. Subsoil contains minerals that plant roots can reach if they grow deep enough.
Below that is the parent material — broken-up rock. And at the very bottom is solid bedrock — the original rock that everything above it came from.
Soil is made of four ingredients mixed together: minerals (tiny bits of broken rock), organic matter (decomposed plants and animals), water, and air. The best soil for growing plants has about 45% minerals, 5% organic matter, 25% water, and 25% air.
**Did You Know:** It takes about 500 years to form just one inch of topsoil! That is why we must protect the soil we have.