Science Buddies: "Ask an Expert"

Posted on behalf of student
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https://www.sciencebuddies.org/science- ... erve-water

I am currently building this circuit, and want to try to get a measurable number from the amount of water in the soil. Could I attach a multimeter in order to get a measurable number? How would I attach it to the circuit while still being able to stick the two probes into the soil?

Hi - this circuit is not really designed to give you a continuously variable number that corresponds to soil moisture level. The voltage you would measure - in row 2 on the left side of the breadboard - will either be "high" (about 9 volts) for 'wet" or "low" (about 0 volts) for "dry." If you want to get a better measurement of soil moisture level, we recommend looking into this project and the soil moisture sensor it uses: https://www.sciencebuddies.org/science- ... t-watering