Design, manufacture and evaluation of capacitive sensors to measure soil moisture

Precision agriculture is a new notion in modern agriculture. One of the reasons of the precision agriculture's growth among scientists and farmers, is the technological advancement in different fields including the geographic path system(GPS), sensors, aerial photos or satellite ( or RS ) and geographic information management facilities . Existence of parametric detection problems in the field of laboratory operations in the agricultural sector, particularly the detection of soil moisture persuade the specialists that always try to reach a suitable solution for soil moisture measurement needed for the plants and interested areas. So in this investigation it is tried to enable the detection of soil moisture by designing and making a hygrometer sensor which has been used of capacitive property in it. This capacitive sensor consists of two insulated aluminum plates that changes by changing the soil moisture, index of dielectric capacitor and its capacitance and frequency of the output circuit . From the characteristics of the device it can be detected to simultaneously moisture detection at several points of the field and also usage in control of the watering amount required by the plants. This machine in vitro was tested in 80 areas and for more exact tests by other different sensors. The mean error percentage received by the capacitive sensor is 0.60%.