Development of a low Cost Soil Moisture Sensor

The main role of soil moisture sensor is to measure the moisture content present in a soil and thus it is helpful in efficient irrigation management practices. This paper outlines the soil moisture sensor designed using the capacitive measurement principle due to its advantages of low cost and high sensitivity over other methods. The DC and AC analysis is performed over the soil using this sensor to explore the properties of soil e.g. capacitance, dielectric constant etc. which can be very useful for many applications e.g. hydrology, agriculture and weather forecasting departments. The dielectric properties of different type of soils are studied at the frequency range of 100 Hz - 1 MHz and it is observed that dielectric constant of soil, which is directly proportional to capacitance, increases with increased moisture content of soil and decreases with it vice-versa. The DC analysis proves that the moisture content increases the electrical voltage of the soil by 70-80% if compared with the dry soil electrical voltage, whereas AC analysis emphasis on the frequency range which is ideal for stable performance of designed capacitive soil moisture sensor.