To make a soil suspension, you'll typically mix soil with water in a specific ratio and then agitate the mixture. Here's a straightforward method:
Materials:
- Air-dry soil (passed through a <2 mm sieve)
- Deionized water
- Bottle or container
- Shaker (mechanical shaker preferred)
- Weighing scale
Procedure:
- Prepare the Soil: Ensure your soil is air-dried and sieved to remove larger particles. This helps with uniform suspension.
- Determine the Soil:Water Ratio: A common ratio is 1:5 (soil:water). For example:
- 10 g of soil to 50 mL of deionized water
- 20 g of soil to 100 mL of deionized water
- Note: You can adjust the amounts, but maintain the 1:5 ratio.
- Weigh the Soil: Accurately weigh the desired amount of air-dry soil.
- Add Soil and Water to Container: Place the weighed soil into a suitable bottle or container. Add the corresponding amount of deionized water.
- Shake the Mixture: Seal the container and shake it vigorously. Mechanical shaking is recommended for consistency. Shake for 1 hour at approximately 15 rpm. This ensures proper dispersion of soil particles in the water.
- Let the Suspension Settle (optional, depending on use): The amount of settling needed depends on the use of the suspension. Some analyses require the suspension to be used immediately after shaking, while others require the larger particles to settle out before further analysis.
Example:
Here’s a table illustrating the 1:5 ratio:
| Soil (g) | Deionized Water (mL) |
|---|---|
| 10 | 50 |
| 20 | 100 |
| 30 | 150 |
| 40 | 200 |
Why this method?
This method creates a homogenous mixture of soil and water, allowing for representative sampling and analysis. The shaking step is crucial for separating soil aggregates and dispersing particles. Using deionized water eliminates potential interference from minerals or other substances present in tap water.
