Drop & shatter test

The drop & shatter test is a useful method for determining the soil structure type and aggregate sizes in a soil horizon.

Equipment:

• Garden spade
• Big, firm container (large bucket)
• Large transparent plastic bag/sheet to organize the aggregates.

Time needed:

1 hour per sample (3x20min = Time for digging (depends on soil compaction), aggregates organization and scoring).

Procedure:

1. At each sampling point, first remove the roots and plants aboveground.
2. Dig and remove a 30x30x30cm cube of topsoil with the spade.
3. Drop the soil sample a maximum of three times from a height of one metre (waist height) onto the firm base of your container. If large clods break away after the first or second drop, drop them individually again once or twice. If a clod shatters into small units after the first or second drop, it does not need dropping again. Do not drop any piece of soil more than three times.
4. Transfer soil onto large plastic bag
5. Organize the aggregates by size: move the coarsest parts to one end and the finest to the other end to obtain a measure of the aggregate-size distribution.
6. Compare your distribution of aggregates with the three photographs below.

Results:
 
Compare your aggregates size with the following photographs to give a score to your soil sample:  

2 = GOOD                                                   1 = MODERATE                                          0 = POOR

– Good condition (2): Good distribution of finer aggregates with no significant clodding.

– Moderate condition (1): Soil contains significant proportions of both coarse firm clods and friable, fine aggregates.

– Poor condition (0): Soil dominated by extremely coarse, very firm clods with very few finer aggregates.