The SparkFun Qwiic Soil Moisture Sensor is a simple breakout for measuring the moisture in soil and similar materials. The soil moisture sensor is pretty straightforward to use. The two large, exposed pads function as probes for the sensor, together acting as a variable resistor. The more water that is in the soil means the better the conductivity between the pads will be, resulting in a lower resistance and a higher SIG out. This version of the Soil Moisture Sensor includes a Qwiic connector, making it even easier to use this sensor!
To get the SparkFun Soil Moisture Sensor functioning, all you will need is to connect the VCC and GND pins to your Arduino-based device (or compatible development board). You will receive a SIG out, which will depend on the amount of water in the soil. One commonly known issue with soil moisture senors is their short lifespan when exposed to a moist environment. To combat this, we’ve had the PCB coated in gold finishing (ENIG, or Electroless Nickel Immersion Gold).
Note: Check the Hookup Guide below for assembly and weatherproofing instructions, as well as a simple example project that you can put together yourself!
Based on 2 ratings:
I recently bought this sensor and regret my purchase after seeing that video. I don't know why they still make these if it leads to corrosion after a while. It seems like they are trying to optimize a device that shouldn't be optimized by adding a gold plate. Also, are the readings less accurate with the ions in the soil? I am still trying to get it to work on a Raspberry Pi, but am less motivated after knowing it may corrode and capacitance measurements would be a better option. Now I am out $9 :(
Following the guide, calibration is definitely important with these, but once dialed in to the soil and the peculiarities of each individual sensor, the measurements roughly align, which is all I need. My only concern is the inability to turn off the power LED via I2C. I use these in a grow tent with photoperiod plants and needed to permanently disable the power LED.