Measuring Soil Physical Properties by Sensor Fusion Technique

Soil water content, mechanical strength and EC (Electric Conductivity) may significantly impact on plant growth and crop yield. For the simultaneous measurement of these physical parameters in the field, it has been desired for many years. This study presented a sensor fusion system, which consisted of five kinds of sensors. In particular, a triple-sensing cell was designed with an international standard (ASAE Standard). This cell included a fringe field sensor for water content, a four-electrodes sensor for EC and a strain gauge sensor for mechanical strength. Besides, there is Hall-current sensor is used to measure the operating current of DC motor. By analysing the energy transformation between electric and mechanism, it is concluded that Hall-current sensor is able to replace the force sensor in principle. In order to verify the performance of the designed system and confirm the relevant theoretical analysis, diverse calibrations and dynamic tests were conducted with three soil textures. The results demonstrate that the sensor fusion system may meet basic requirements of investigation in precision agriculture.