|Letís take a closer look at
the top horizon. You could
also call this the surface horizon, or the A horizon.
It is dark in color. Do
you know why? Because organic
matter has been added to the soil.
matter comes from the plant roots, leaves, and other material as it breaks
down and decomposes in the soil. Microorganisms
use this organic matter for food. Do
you see below the second nail, the soil looks lighter?
Do you know why? There isnít as much organic matter down there.