Soil Characteristics
PHYSICAL GEOGRAPHY 101

Color

Indicates composition of the soil

Texture

Proportion of particle sizes present in soil
Sand, silt and clay
Size classification
Determines the water retention capacity

Soil Colloids

Particles less than 1/100,000 mm (0.00001)
Very fine clay mineral particles and organic matter
Tend to attract nutrient to their surfaces

Soil Acidity/Alkalinity

Dependent on presence or absence of H⁺ ions
Acidic soil is caused by many factors including climate, pollution precipitation, and bedrock.

Soil Structure

Refers to the way the soil grains are grouped together
These groupings are called peds
Bound together by colloids

Soil Minerals

Minerals found in the soil.
Primary minerals - minerals derived from the bedrock
- quartz, feldspar, mica, hornblende, pyroxene, olivine, calcite
Secondary minerals - produced by the chemical weathering of primary minerals
- clay minerals, mineral oxides

Soil Moisture

Amount of water retained in the soil after excess water has drained
Excess water is removed by evaporation, transpiration, groundwater transport

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