Plants as Bioindicators: the Soil pH Test
To test the existing data about plant bioindicators in your region.
Note: You can make multiple soil pH measurements, but you will need a bag or container for each sample, as well as additional distilled water.
- Guides to plants that contain images of plants. They should also include each plant’s Latin name and the pH range that it needs to survive. OR
- Smartphones, tablets, or other mobile devices
- A camera or a smartphone, tablet, or other mobile device with a camera. You can use the same mobile device as you use for step 2.
- A pH measuring tool. Use any that is available:
- litmus paper,
- pH meter with a probe,
- pH level digital sensor.
- A gardening trowel
- A plastic bag(s) that can be sealed or a plastic container(s)
- Distilled water
NOTE: Keep the water sealed until you use it. Also, refer to the user manuals of the litmus paper or your pH level probe to determine how much water you will need to measure a soil’s pH. If you intend to make multiple measurements, be sure to have enough distilled water for each.
- A pen/pencil and a piece of paper to to record your measurements. You can download and use this template.
If you use Globisense or Fourier pH digital probes, please refer to the Working with Probes section of the Support page for information on how to submit data from these specific probes to your GlobalLab Report Forms.
Why use data from multiple participants?
Multiple datasets enable us to see if the pH levels where specific plants are growing are the same as those observed in the past.
- Look for images of local bioindicators either from botany books in your local/school library or on the Web. Make sure your source also has their Latin names and preferred pH levels. If you found images and data on the Web, download them onto smartphones or other mobile devices.
- Record the reference information for your resource(s). For books, include their titles, authors, publisher, and year they were published. For information on the Web, record each site’s URL. Also record the date they were last updated. Usually, this information is found in the bottom of the webpage.
Outside in the field
- Go outside, ideally to a field or park, and look for plant bioindicators. Be sure to bring:
a. your smartphones/mobile devices or books with the plant images
- Try to locate a plant bioindicator. Otherwise select one (or a few) plant(s) that are common to your area.
- Enter the name(s) of the plant(s) in the table, including their Latin name(s), and preferred pH level.
- Take a photo of it (them).
- Use the trowel to dig several inches into the soil by the plant’s stem. Try not to harm the plant. Obtain about a tablespoon of soil from this depth and put this sample into a plastic bag or plastic container. Seal the bag or container. Mark it with a number and write down this number in the row with the plant’s name in the table. Repeat this step for each plant you want to examine.
NOTE: If you take more than one soil sample, do not forget to mark the containers for each.
At school or at home
- Mix the soil well in the container, add distilled water, stir, and let the mixture settle for several minutes.
- No later than five minutes after you mixed the soil and water, measure the mixture’s pH level using your available equipment. Please refer to the manufacture’s manual for using pH strips or a pH-sensing device.
- Write down the results in the table.
- Fill in the Report Form.
NOTE: Each plant/pH measurement requires a separate Report Form.
b. a camera or smartphones/mobile devices with cameras
c. the gardening trowel
d. plastic bag(s)
e. the table and a pen/pencil.
- Make sure your local regulations do not restrict taking soil samples.
- Refer to the manufacturer’s manual for safety tips while working with probes.
- Exercise caution when digging in the ground.
- Project was published on:June 29, 2014