Materials needed
- Air-dried soil samples
- One or two round sieves with 2 mm mesh, clean and dry
- The trays designed to fit on the sieves
- A tared aluminum weighing boat for each sample, if the samples contain rocks or indurated nodules
- A mortar and pestle, clean and dry, or improvised system with tray and brass cylinder (Fig. 1)
Procedure
- Fit the sieve into the sample tray.
- Pass the sample through the 2 mm sieve into the tray without strong pressure, using your thumb or the back of a spoon. Don't push too hard; the sample should mostly pass through easily.
- Remove the rocks and rock-like nodules remaining on the sieve to the weighing boat to record their mass later.
- Remove the soil aggregates and other material remaining on the sieve and grind in the mortar and pestle under light pressure: the goal is to break up aggregates but not to grind grains of sand or micas into smaller particles. Return the ground material to the sieve and pass it through.
- Carefully collect the sample from the sieve tray.
- If you are processing multiple samples, the sieves, trays, and mortar and pestle should be clean and dry between each use. You can rinse a sieve and put it into a 105-degree oven to dry while you work on the next sample.
| Figure 1: Breaking aggregates using light pressure from a brass ring on a sample tray |
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