Measure pH of Soil
Soil is made up of tiny particles of rock, plant, and animal matter. Soil acidity can be expressed using the pH scale. The pH scale ranges from 0 to 14. A pH of pH7 is neutral. If the pH is below 7 the soil is acidic, if it’s above 7 it is basic. Most plants can adapt and grow in a soil pH that ranges 6 to 7.5pH, but some plants have distinct preferences, eg Blueberries (Acidic soil).
But why is this important? It controls which nutrients are available in the soil for the plants to use.
In this experiment, you will
- Use a pH Sensor to measure the pH of soil samples.
Go Direct® Tris-Compatible Flat pH Sensor
Laptop/ PC/ Chromebook/ Tablet/ Smart phone
100ml Graduated Cylinder
Soil Samples(in this experiment we use 2)
Two Beakers with spoons (1 set per sample)
Wash bottle with distilled water
Prepare the water-soil mixture.
a. Label two beakers “A” and “B”.
b. Place 50 g of Soil A into Beaker A. To avoid cross-contamination of the soils, leave this
spoon in the beaker.
c. Using a new spoon, place 50 g of Soil B into Beaker B. Leave the spoon in the beaker.
d. Add 100 mL of distilled water to each beaker.
e. Stir both mixtures thoroughly.
f. Stir once every three minutes for 15 minutes.
g. After the final stirring, let the mixtures settle for about five minutes. This allows the soil
to settle out, leaving a layer of water on top for you to take your pH measurement.
On the Go Direct® Tris-Compatible Flat pH Sensor, press the power button once. The LED will blink red. Launch the Graphical Analysis App. Click Sensor Data Collection. Now select GDX-EA from the list (if you have more than one device, select the serial number corresponding to that on the case). The LED on the connected sensor(s) will now blink Green. Click DONE.
Note: If the pH sensor needs calibrating follow the pH sensor Calibration instructions here.
- Carefully place the tip of the pH Sensor into the Liquid part of Beaker A. Making sure the glass bulb is submerged.
- If the pH value is stable record this value.
- If the value is not stable then we need to determine the mean (or average).
- Click Mode in the bottom left corner and change the duration to 10s.
- Press collect to start the data collection. Important the tip must be kept submerged during the collection
- When the 10seconds has finished clicking the graph icon(bottom left) then click View Statistics
- Record the mean from the Statistics box
- Rinse the pH sensor with distilled water and repeat steps 1-3 with the sample in Beaker b.
- Rinse the pH sensor with distilled water and put back into its storage container.