Good soil is the secret to healthy plants, so the more you can understand your soil, the better. This easy soil texture test will help you determine the percentages of sand, silt, and clay in your soil.
The ideal soil makeup consists of about:
- 40% sand
- 40% silt
- 20% clay
Determining the texture of your own soil will guide you in amending it to the perfect balance. Here are simple step-by-step instructions for testing the texture of your soil.
- Indelible marker
- Clear quart-sized jar (straight-sided jar best)
- Spoonful of powdered laundry or dish detergent (dispersant to aid in settling)
How to Test Soil Texture
Step 1: Dig Soil Sample
Remove the top 2” of soil and all the grass roots. Dig a small, straight-sided hole at least 8” deep. Pointing the shovel straight down, slice off a chunk of soil about 1” thick and carefully lift it out of the hole. Remove any roots, twigs, or rocks.
Step 2: Deposit Soil Sample in Jar
Use the shovel to slice off a small cross section of the soil sample. Place the soil in the jar, so that the jar is about 1/3 full of soil.
Step 3: Add Water and Detergent to Jar
Fill the jar with water, add a teaspoon of detergent, and shake for several minutes until the soil is thoroughly suspended in the water.
Step 4: Wait and Measure
The coarse sand particles will settle out first; followed by the darker, finer silt. Last will be the lighter, superfine clay while organic matter will float. If you wait until everything has settled, it can be hard to sort out which is which. To make identification easier, mark the sand level on the jar after one minute, the silt level after 4-6 hours, and the clay level after two days. The sample above was taken from my yard.
Step 5: Calculate Soil Percentages
Once the soil has settled, it’s time to determine the percentage of sand, silt, and clay relative to the total soil level. To calculate the percentage, divide the depth of each layer of soil by the total soil depth in the jar, and multiply by 100. The above sample was taken from farmland in eastern North Carolina – note the high sand level and near-absence of floating organic matter.