Soil Study Guide

1
Soil Study Guide

• Soil is loose material that covers much of the
  Earths surface.
• Soil is made up of bits of rock, minerals, and
  material that was part of once living things.
• Soil forms when rocks are weathered.

• Humus
• Humus is decayed remains of plants and animals.
• Humus has lots of nutrients in it which makes it
  easy for plants to grow.
• Large amounts of humus are found in forests.

• Soil Layers
• Topsoil
• Top layer
• Plants grow best here
• Large amounts of humus
• Subsoil
• Bottom layer of soil
• Contains little humus
• Contains small pieces of rock
• Bedrock
• Solid unweathered rock
• Below the subsoil

2

• 3 Types of Soil
• Sandy Soil
• Largest particles
• Water passes through it easily
• Silt Soil
• Particles are smaller than sandy soil, but larger
  than clay soil.
• Clay Soil
• Smallest particles
• Water does not pass through it easily
• Soaks water like a sponge

• If you had a jar full of the 3 types of soil
• Sandy soil would be at the bottom because the
  particles are bigger and water passes through
  them easily.
• Silt would be in the middle because the particles
  are smaller than sandy soil but larger than clay
  soil.
• Clay soil would settle last because the particles
  are so small they fall very slowly.

Relative soil particle sizes
SAND
CLAY
SILT
.
Invisible at this scale