Design and evaluation of fiber-based Sensors using in soil moisture monitoring

Lack of water resources due to droughts and mismanagement of water consumption, has been paid more attention to provide effective solutions to increase water productivity, especially in the agricultural sector. One of the most important solutions in this regard is the use of soil moisture monitoring systems. In such systems, the performance efficiency of moisture sensors used in the soil possesses particular importance. In this study, moisture sensors based on fiberglass structures were designed and manufactured in 2021 and their performance was characterized. For this purpose, the sensors were designed in the form of porous blocks containing four types of fiberglass woven structures as membranes (P200 ،T281 ،P296 و P186). The results of statistical studies showed that P200, P296, T281 and P186 sensors had acceptable accuracy for estimating soil moisture, respectively. Based on RMSE the sensor equipped with P200 and P186 membrane had 0.05 and 0.065 error that were the lower and highest accuracy in measuring soil moisture. Also, the performance of the designed sensors in ten soil textures showed that the highest measurement accuracy was in medium to light soil texture. So that in P200 sensor the Sandy loam soil texture (with nRMSE=0.004), P186 sensor the Loam and Sandy Loam soil texture (with nRMSE=0.097-0.099), P296 sensor the Loam soil texture (with nRMSE=0.071) and T281 sensor the Silty Loam soil texture (with nRMSE=0.07) had the highest accuracy. The results showed that the type of membrane is effective on the efficiency of the sensor and the choice of membrane is suggested depending on the soil texture. Except P186 membrane, other membranes have acceptable accuracy and their low cost, ability to store and send soil moisture data to processing systems, recommend their use in smart irrigation system.