Acid Rain Experiments – Experiment 5 – Measuring Soil pH

In this experiment you will collect soil and measure its pH. The pH is one of several important conditions that affect the health of plants and animals. In addition, you will also be asked to survey the plants and animals that live in the area where you collected the soil. Area surveys provide information about how well plants and animals can live under different conditions.

For this experiment, you will need an inexpensive garden soil pH test kit, which may be obtained from lawn and garden stores or nurseries.

Materials

garden soil pH test kit
distilled water
2 cups soil from each of two or three different locations (some of the soil will be needed for the “Soil Buffering” experiment)
measuring spoons
digging tool
self-sealing plastic bags
notebook and pencil

Instructions

Pick two or three different soil locations, such as a garden, wooded area, city park, or meadow. Ask an adult to go with you.
At each location, observe the plants and animals living in or rooted on these soils, especially those that are in greatest numbers. Write down as much as you can about what you find. Dig down about 2 inches, scoop out 2 cups of soil, and seal it in a plastic bag for later use. Label each plastic bag. Be sure to clean your digging tool after collecting soil samples at each location.
Measure the pH of each soil sample following the directions provided in the garden soil pH test kit, and record the approximate pH of each soil sample. Save the excess soil from each site for use in the “Soil Buffering” experiment.

Questions and Answers

Were there any big differences between the plant and animal life at each location?

Some types of plants and animals are able to live in acid soils, while others are not. Be aware, however, that many factors, not just the soil acidity, determine the types of plants and animals that occur at a particular site.

Were any of your soil samples acidic?

Some plants require acid soils to grow and thrive. For example, pine trees, azaleas, rhododendrons, cranberries, blueberries, potatoes, and tomatoes prefer acid soils. However, most plants thrive only in soils of pH 6 to 7.

Were any of your soil samples basic?

Some soils, such as in many in the Midwestern U.S., contain a lot of limestone and are alkaline. In those locations, people often add sulfate, such as ammonium bisulfate to soil to make it less basic.