Soil slaking test

The slake test is a simple way of assessing soil structure. Slaking indicates the stability of soil aggregates, resistance to erosion and suggests how well soil can maintain its structure to provide water and air for plants and soil organisms when it is rapidly wetted.

Note: the slaking test is not very effective in soils with a high content of clay.

Material :

• Glass bottle/jar per sample
• 1cm mesh
• Water

Time needed:

Around 15 minutes per sample

Procedure:

1. Fill the jar(s) with water
2. ‘Hang’ a piece of the mesh inside-/at the top of each jar (to prevent the soil sinking to the bottom directly)
3. Take an air-dry soil aggregate (4-6 cm diameter) from each zone (if you have conducted the drop and shatter test, select three pea-sized aggregates of soil from each soil zone)
4. Place different soil fragments in different meshes/jars
5. Observe soil fragment for 10 minutes
6. Take a photo for record

Results:

Note: Soils with high Soil Organic Matter (SOM) contents do not readily slake (fall apart) when wetted (left side).

The soil test on the right would be more likely to crust after a heavy rain.

Give a score to your test after 10 minutes:

1= Complete slaking/poor condition (aggregate breaks down completely into grains)

2= Partial slaking/moderate condition (aggregate breaks but some remain intact on top)

3= No slaking/good condition (no change, water is clean)

Record your results in the table below:

Limited slaking suggests that organic matter is present in soil to help bind soil particles and microaggregates into larger, stable aggregates.