This is an easy way to measure the amounts of sand, silt, and clay in your garden soil. It’s not life-changing or rocket science but it will help you understand the composition of your soil and just how much your garden may be in need of ongoing organic amendments (like nice, rich humus from organic compost).
If you want your soil analyzed, we shared our experience with home test kit versus a laboratory test here.
How to Know if Your Soil is Sand, Silt, or Clay
I’ve actually been wanting to do this for ages, just for fun, but the result of my test was so absurdly predictable I’m surprised the soil didn’t jump right out of the jar and say, I told you so! You’ll see what I mean.
Supplies
- Clean 1 L / 30 ounce mason jar with lid
- Trowel
- Garden soil
- Water
- 1T Dishwater detergent or water softener
- Ruler
Related: 50 Plants for Clay Soil | Flowering Perennials, Shrubs, and Trees.
Simple Un-Scientific Soil Composition Test
1. Dig an 8-inch deep x 4-inch wide hole in one of your garden beds.
2. Use soil to fill mason jar 1/3 full. Ideally this sample will include soil from all layers.
3. Fill rest of jar with water, leaving an inch or two at the top for shaking space.
4. Add 1 tablespoon dishwasher detergent or water softener.
5. Tighten lid and shake thoroughly. Shake, baby, shake.
Results
The entire waiting period is 24 hours but you can see partial results along the way:
Sand
- The sand layer will sink to the bottom first and is often visible after just 5 minutes.
Silt
- Silt forms a distinct 2nd layer after two hours or so.
Clay
- Clay is the last and can take 24 hours to settle.
Any particles floating in the top water are miscellaneous organic matter.
After 24 hours, use a ruler to measure your layers, excluding the water on top.
For example, if all of the layers together measure 6″, what portions of the total are sand, silt, and/or clay? Most will have some of each: sand, silt, and clay.
In my case, it’s almost 100% sand (see below)! My old garden was almost 100% clay. This girl can’t catch a break! See the tide line just above the word ‘Mason’ in the photo below? That’s a trace of clay, the rest is sand. (The bottom white-ish part is just light reflecting on the jar.) Maybe life is a beach. Or my garden is.
Extra Help Needed
All gardens can benefit from amending the soil but garden soil with more 1/3 sand or clay composition is calling out for immediate help.
In a naturalized garden, dead plants would be left to rot and return nutrients to the soil.
In our cultivated gardens, we clean up that stuff so we have to also add it back with compost (humus).
Treatment for Poor Soil
I have found the same treatment works well for sand and clay: I amend each bed twice a year with a thick layer of organic, compost and natural wood chip and bark mulch on top to keep moisture in (sandy soil dries out fast).
- With sandy soil, there’s no point in digging in the compost because it just washes away.
- With dense, clay soil there’s no point in digging it in because you can’t dig!
- For both, just add the compost on top and let it build up over time.
If you’re lucky, your soil won’t be nearly as extreme as mine.
Next Step
A proper soil analysis from a lab can be highly informative for understanding your soil composition and what its needs are.
We compared a home soil test kit and a proper lab test here.
If you are able, consider having a test done and be sure to choose a lab that will provide specific recommendations for improving your soil.
~Melissa the Empress of Dirt ♛
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