A soil moisture sensor can read the amount of moisture present in the soil surrounding it. It's ideal for monitoring an urban garden, or your pet plant's water level. This is a must-have component for an IoT agriculture!
The new soil moisture sensor uses Immersion Gold which protects the nickel from oxidation. Electroless nickel immersion gold (ENIG) has several advantages over more conventional (and cheaper) surface platings such as HASL (solder), including excellent surface planarity (particularly helpful for PCB's with large BGA packages), good oxidation resistance, and usability for untreated contact surfaces such as membrane switches and contact points.
This soil moisture Arduino sensor uses the two probes to pass current through the soil, and then it reads that resistance to get the moisture level. More water makes the soil conduct electricity more easily (less resistance), while dry soil conducts electricity poorly (more resistance). This sensor will be helpful to remind you to water your indoor plants or to monitor the soil moisture in your garden.
To ease the difficulty of using this sensor, a Gravity Interface is adapted to allow plug&play. The Arduino IO expansion shield is the best match for this sound senor connecting to your Arduino. This sensor can work at 3.3V which makes it compatible with Raspberry Pi, intel Edison, joule and curie.
Note: If you are going to place the sensor to very humid soil, that would make it very easy to get the sensor surface erosion within several days, hence we suggest using this one Analog Capacitive Soil Moisture Sensor- Corrosion Resistant instead.