
Clay Soil and Electrical Charge
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Does clay in soil carry an electrical charge? Soil scientists know that tiny clay particles attract and hold plant nutrients. You can see this attraction for yourself with a simple battery setup.
You mix clayey soil into a jar of water and let it settle for ten minutes. Then you connect two copper wires to a 6-volt lantern battery and lower the bare ends into the murky water. After 10 to 15 minutes, you pull the wires out.
One wire will have clay clinging to it. The other will be mostly clean. Which terminal attracted the clay reveals whether the particles carry a positive or negative charge.
Hypothesis
The hypothesis is that soil can act like an electrical system and can be used to attract and hold plant nutrients.
Method & Materials
You will place 60 grams of clayey soil in a 500 mL jar, add 500 mL of tap water, stir or shake the container, let the suspended soil settle, connect one end of each wire to the terminals of the battery, and place the other ends of the electrical wires in the clay suspension.
You will need 60 grams of clayey soil, one 500 mL glass or plastic beaker or jar, one 6 volt dry-charge lantern battery with two screw top terminals, and two pieces of 12 gauge, plastic insulated, multiple strand, twisted copper wire about 50 cm in length.
Results
The experiment confirms the electrical principle that likes repel and unlikes attract. It also confirms the fact that soils are electrical chemical systems that provide remarkable potential to attract and hold plant nutrients. The more positive charges associated with the nutrient, the tighter the adsorption to the soil.
Why do this project?
This science project is interesting and unique because it demonstrates how soil can act like an electrical system and how it can be used to attract and hold plant nutrients.
Also Consider
Experiment variations to consider include using a Methylene Blue dye solution instead of a clay suspension, and using silver chloride as the plating material in an electrolysis experiment.
Full project details
Additional information and source material for this project are available below.Related video
These videos explain the science behind this project and demonstrate key concepts used in the experiment.
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