Soil moisture sensor systems and methods are disclosed. An exemplary soil moisture sensor system includes a sensor configured to receive soil between parallel plates. A capacitive measurement circuit is operatively associated with the parallel sensor. A processor receives input from the capacitive measurement circuit. The processor determines moisture content of the soil between the parallel plates of the sensor based on the flowing relationship:.times..times. ##EQU00001## where L is the length of the sensor, H is the height of the sensor, and d is the separation between the parallel plates of the sensor.