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Soil Air

All that is needed for this experiment is a can of spray polyurethane and some soils clods.

photo of the supplies for this experiment -- soil clods and spray polyurethane

Spray the clod and wait a minute or two before dropping the clod in a jar of water. Watch the bubbles. Air will bubble from some clods for up to 20 minutes or more.

photo of a soil clod in a jar of water

Soil clods from surface soils from orchards, pastures, and lawns generally will have a high soil air content and will bubble longer.

photo of a soil clod in water that has high soil air content (bubbles longer)

Soil clods from subsoils, or soils from conventionally cultivated fields will generally have lower soil air content and will bubble less.

photo of a soil clod in water that has lower soil air content (bubbles less)