This is a simple soil moisture sensor, when the soil is wet 

the analogue sensor output value will decrease,
and vice versa. Use this sensor to make an automatic
watering system for when you are not at home

Supply voltage: 3.3V or 5V
Operating Current: less than 20mA
Output voltage: 0-2.3V (2.3V is completely immersed in water voltage value),
5V power supply, the greater the humidity, the greater the output voltage.
Sensor Type: Analogue Output.