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Materials
- 3 - 4 air-dried aggregates 4 - 6mm in diameter of the soil you wish to test (it is very important to air dry the samples)
- Rain water or distilled water
- Flat bottom dishes eg. shallow glass or transparent plastic cups
The activity
- Introduce this activity by talking about the fact that the roots of a plant are living and need to be supplied with oxygen, water and nutrients. These must be obtained from the soil. If the soil disperses easily in water then it is prone to water logging and the roots will not get oxygen and nutrients moving into them.
- To test how dispersive your soil is, half fill a flat bottomed dish with water.
- Take 3 - 4 clumps of soil of approximately 4-6 mm in diameter that have been dried in the air and place them in the flat bottomed dish containing water.
- Leave undisturbed for 20 minutes then check for dispersion. If the soil is highly dispersive a cloud will cover the bottom of the dish
- Leave for a further 24 hours checking after one hour if possible and recording observations on how cloudy the bottom of the dish is.
- If the aggregates are non-dispersive this is excellent and the soil will offer no problems to the plants and gardeners.
- Compare class results and discuss what action may be taken to ensure your soil is suitable for growing plants.
Extension activities
Investigate the surface soil and the upper and lower subsoils. From the data from all three layers you can then decide how deep you will dig and whether the top layer only needs to be manipulated.
Related LandLearn activities
Soil texture, soil strength and others contained in the Soils Ain't Dirt booklet on the LandLearn Resource Booklets CD.
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Healthy Soil for Your Plants - Worksheet
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