Design and Calibration of a Device for Irrigation Recommendation With 10HS and 5TE Sensors

Abel Quevedo Nolasco¹, Graciano Javier Aguado Rodríguez²

Abstract: In the context of plant water consumption, the first question is: How much water is required to irrigate? The answer is usually: “It depends ...”. Therefore, the aim in this study was to develop an easy-to-use device, based on the Arduino Mega 2560® card and, capable of detecting soil moisture levels (by using 10HS and 5TE sensors) to recommend irrigation needs for any pot size. Factory-supplied and specific calibration methods were used to determine the soil moisture of a sandy-soil and a loam-soil in two pot sizes: the small cylindrical pot (13 cm height ´ 20 cm diameter) and the big cylindrical pot (28.5 cm diameter ´ 35.5 cm height) during January and February 2022. As key results, it was observed that the specific calibration equation had an R2 of 0.98 and an accuracy (RMSE) of 0.0108 m³m^-3 was obtained by using the 10HS sensor and 0.0116 m³m^-3 by using the 5TE sensor. It was found that only one measurement of soil moisture is required to obtain in general a margin of error less than 0.02 m³ m^-3, and an error of 0.01 m3m-3 can be achieved if two measurements of soil moisture are made (in the sandy soil).

Key words: soil moisture, water volumetric content, sample size, margin of error, sensor accuracy