Performace analysis of simple capacitive cylinder sensor for measuring soil moisture content

This paper studied the performance of a cylinder sensor on measuring the soil moisture content for an automatic irrigation supply purpose. The proposed sensor was generated from a simple capacitive cylinder made from combination of aluminium, stainles steel and pertinax to construct the outer, inner and electrode isolator, respectively, avoiding the effect of soil salinity. The objective is to determine the response of the proposed sensor in measuring the soil moisture content for various level. To measure the moisture content, the proposed sensore equipped with a stable Multivibrator (AM) circuits and Arduino Multicontrol. Changes in sensor capacitance value indicate the change in soil moisture levels, generating a signal in AM circuit, which were then converted using Arduino microcontroller and displayed on the LCD screen. The test showed that, the range value for sand samples are 78, 662 to 1, 035 Hz, while for clay are 74, 551 to 932 Hz. The regression model showed an exponential relationship between soil moisture content and the frequency of the electrical signal generated by the equation y = 123872e^-0.229x with R² equal to 0, 9127.