The SparkFun 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 3-pin screw pin terminal pre-soldered to the board for easy wiring and setup.
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, SparkFun 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!