Optional Activity: Assessing Soil Texture
Healthy soil is so essential for a healthy garden that this is the one activity in the course where you will have a chance to get your hands dirty in this course. Students in my Organic Gardening course use these methods to assess their soil, and sometimes they are surprised at what they find.
Before you commit to a particular garden site, you can use these easy soil assessment techniques to learn more about the soil. This may help guide your choice as to where to place your garden.
If you already have an existing garden site, you can use these activities to assess the soil in your beds. It can be interesting to compare soil from garden beds with unimproved soil nearby, for example from a lawn near the garden, to see how they differ.
These soil assessments are also fun to do with youth or community garden members!
If it's a time of year when your soil is frozen or covered with ice and snow, come back to this activity at a later date.
Please watch the video:
Then complete The Ribbon Test, The Shaker Jar Test and either Percolation Test A or B. The instructions are outlined both in the video and in the text, below.
Things you will need for this activity:
- Several days to complete it
- Soil samples, about 1 cup for every sample you want to test
- Water source
- Spoon or small shovel
- Jar with tight fitting lid (quart size is best)
- Kitchen timer or stop watch
- Marker or tape to make marks on your jar
1. Ribbon Test
- Gather 1/2 a cup of soil from where you would like to test. Discard large rocks. If soil is VERY DRY, you may need to add a little water. If soil is VERY WET you will need to let it dry out. Ideal moisture feels similar to a wrung out sponge.
- Squeeze soil in your bare hand (so you can feel it with your skin!); if sample falls apart = Sand
- Try to make a ball with the sample. If you can make a ball = Loamy Sand
- If you have something that resembles a ball of soil, squeeze it
slowly through your thumb and pointer fingers to try to form a ribbon as
long as possible
A longer ribbon indicates more clay in the soil, and a shorter ribbon indicates more sand in the soil. This video shows all the steps of this test, using different soil types as examples:
2. Shaker Jar Test
1. Pick several spots in the garden and dig with a trowel about 8" down below the soil surface.
2. Fill a quart jar 1/2 full of soil, fill the rest with water & shake for 3 min.
3. Let settle for 24 – 48 hours (heavy clay soils will take longer).
4. Sand will settle first on the bottom, followed by silt, then clay, then organic matter (floating on top).
Optional measurements - Each layer is a percentage of the entire layer of dropped soil particles. Measure each of the 3 layers and divide each layer height by the total height. Then multiply by 100 to find the percentage of sand, silt and clay. A soil that is abundant in clay will, of course, have the highest percentage of a clay component...and so on. Note: Any dark colored material floating in suspension in the water is organic. You will have to estimate how much of this you have or scoop it off to measure it in a dry jar of the same size and shape. Note: If you used potting soil from house plants, you may not get very clear sand and clay layers.
3. Percolation Tests (Choose either A or B)
A. Outside Test: Dig a pit approximately 1-foot deep. Fill with water and allow it to drain completely, then refill and measure depth of water. After 15 minutes, note depth and calculate rate as inches/hour.
B. Desktop Test: Take several 2-liter soda bottles (or gallon jug or equivalent) with labels and tops removed. Poke several pencil sized holes around the bottom. Fill halfway with soil from test spots. Fill once and let drain. Then fill again and time how long it takes to drain, while making observations as it flows through. Calculate inches/hour.
- Poor = < 4"/hr
- Moderate = 4" – 8" /hr
- Well = > 8"/hr
Repeat these tests if you have more than one garden or landscape space that you want to check. Don't assume that all the soil in your garden or landscape is exactly the same.
> To submit, click on "Add Submission" below. That will open a text box in which you should answer these questions:
1. What color is your soil sample - be specific? Does it feel gritty or smooth?
2. Did each of the tests above indicate the same soil type?
3. What soil type did you determine you have?
4. If your soil is sandy, how will you make it more of a loam? If your soil has a lot of clay, how would you make it more of a loam?
5. Click "Save" at the bottom of the page.