Determine Your Soil Texture with the Simple Jar Test

Knowing your soil’s sand, silt, and clay percentages helps you choose amendments, estimate water needs, and understand fertility. The jar test is a quick, low‑tech method.

Jar Test Procedure

1. Dig 6″ deep in 3 spots; combine for a representative sample.
2. Place ½ cup soil in a quart jar.
3. Add 1½ cups water.
4. Add ½ tsp salt or dish detergent (helps particles separate).
5. Cap and shake vigorously for 2 minutes.
6. Pour into a 2‑cup Pyrex measuring cup.
7. 30 seconds: Measure settled layer height (sand). Record.
8. 30 minutes: Measure again. Subtract sand height = silt layer.
9. 24+ hours: Measure final height. Subtract 30‑minute height = clay layer. If water still cloudy, wait until clear and measure again; use that value if higher.
10. Convert the three heights to percentages of total height.

Example Calculation

Using the soil texture triangle, 50% sand / 12.5% silt / 37.5% clay = Sandy Clay Soil.

Soil Texture Basics

• Sandy soil: Large particles, drains fast, holds nutrients poorly.
• Clay soil: Tiny particles, holds water and nutrients well, but sticky, heavy, cracks when dry.
• Silt soil: Medium particles; adds little character alone.
• Loam: Balanced mix of sand, silt, and clay—ideal for most plants.

Once you know your texture, you can amend appropriately: add organic matter to sand for moisture retention, or to clay for drainage and structure.

Originally published at Reply42.com/garden Soil Tilth; reused with permission.