This Soil Moisture Sensor Module included two parts. One is the signal processing-amplifier LM393. Other is moisture sensor. It can use to detect the moisture of soil, to judge if there is dampness around the sensor. It can be used to decide if the plants in a garden needs watering. With this module, we can adjust the potentiometer to threshold of the signal, when the humidity is lower than the set value, the D0 will output high level, otherwise, D0 output low level. Also this module can output analog signal, it can be used very easily by just inserting the sensor into the soil and reading the output using ADC.