Unit 2 Earth's Resources Lesson 5 Soil Formation

Soil

a loose mixture of small rock fragments, organic matter, water, and air that can support the growth of vegetation

Humus

decayed organic matter in soil from decomposers

Soil Profile

a vertical section of soil that shows all of the different layers

Soil Horizon

each layer in the soil profile that has different physical properties

A Horizon

the soil that is at the top of the soil profile; often referred to as the topsoil; decomposers live in this horizon so it has the most decayed organic matter; dark color due to large amounts of humus

B Horizon

the soil horizon not as developed as the A horizon; has less humus; leaching materials commonly give this horizon a reddish or brownish color

C Horizon

the least developed soil horizon; contains the larges rock fragements and uaully has no organic matter; lies directly above the parent rock

Parent Rock

weathered rock from which soil is formed

Soil Texture

a property that describes the relative amounts of differently sized soil particles

Soil Particles

sand, silt, and clay

Sand

the largest soil particle; this type of soil feels course

Silt

soil particles smaller than sand; this type of soil feels smooth and silky

Clay

smallest soil particles; this type of soil feels very smooth and are usually sticky when they are wet

Soil Color

a clue to the type and amounts of minerals and organic matter in a soil, the amount of humus in the soil, or about the enviornmental conditions in which the soil is formed

Soil Chemistry

or Soil pH id determined by the combination of sediment and organic matter found in the soil; based on a scale of 0-14; a measure of how acidic or basic the soil is; pH is measured to determine whether the oil can support different plants

Pore Space

describes the space between soil particles

Soil Fertility

describes how well a soil can support plant growth