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Clay

• Very small particle size (only seen under microscope)

• Often feels sticky

• Poor drainage and very few air spaces (low permeability)

• Large capacity for holding water, expands when wet

• Hard when dry

• Variable soil nutrients (can be low or moderately high)

• Due to low permeability, can become an impervious hardpan layer

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Silt

• Medium particle size​ (larger than Clay particles)

• Feels soft or silky 

• Moderate to poor drainage (low to moderate permeability)

• Moderate capacity for holding water

• Typically rich in nutrients

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Sand

• Relatively large particle size (larger than Silt particles)

• Feels coarse and grainy

• Good drainage, dries quickly

• Low capacity for holding water (Also little or no capacity for bringing water up from deeper layers through capillary transport)

• Typically low in nutrients

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Loam

• Mixture of clay, silt, and sand (typically 20% clay, 40% silt, 40% sand)

• Moderate drainage (moderate permeability)

• Moderate to high capacity for holding water

• Retains moisture while still draining well

• Ideal for growing vegetation 

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Gravel

• Large particles size

• Very high permeability

• Almost no capacity for holding water

• Good as a drainage layer

• Can be used to slow down and disperse rainwater runoff

• Can be used as roadway and driveway surface 

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Soil Porosity Chart

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