What is dirt made of?
(Lansing State Journal, March 8, 1995)

Dirt is a mixture of four things: stones, sand, clays and humus.

Stones of various sizes can be found in some soil.  They may have come from underlying bedrock or may have been carried into the area and mixed in over time.

Sand is tiny crystals and is usually cloudy white or beige.  The spaces between sand particles let water drain into the soil.

Clays are minerals that stick together easily.  Clays generally absorb water, keeping soil moist.

Humus is made of the remains of dead plants and animals that are slowly being consumed by organisms called dentrivores.  Dentrivores break down dead things and return many of the nutrients to the soil.  Most fungi, as well as many bacteria, insects, mites and worms, are dentrivores.

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