Determining soil physical properties by multi-sensor technique

Plant growth and crop yield can be significantly impeded by a number of soil physical parameters including soil water content, mechanical strength and soil electrical conductivity (EC). Therefore, to simultaneously measure these physical parameters along vertical depths in the field, it has been desired for many years. This study focused on developing a multi-sensor system, which contained a cell with three sensors for measuring soil water content, mechanical strength and EC. Additionally a Hall-current sensor was proposed to measure the operating current of a dc-motor, which generated the penetrating force during operating process. Based on the theoretical analysis of the transformation from electrical to mechanical energy, it was feasible to evaluate the soil mechanical strength from the operating current of the dc-motor. In order to verify the performance of the designed system and the theoretical analysis addressed, relevant calibrations and tests were conducted. The results demonstrate that the multi-sensor system could be beneficial and practical for field surveys.