Design, Construction and Evaluation of a Digital Hand-pushed Penetrometer

A cone penetrometer is widely used in tillage and off-road mobility research as an indicator of soil strength and density characteristics. Light-weight, manually operated units are especially useful in recording cone index determination at remote field locations. An electronically hand-pushed soil penetrometer with a microcontroller-based data logging system was designed and fabricated to provide a portable penetrometer for determining soil resistance to penetration in tillage studies. The device consists of three main components: a cantilever beam strain-gauge load cell held by housing to measure penetration force, depth measurement mechanism with a photodiode sensor, and a data logging system for amplifying, digitizing, and acquiring data. Data from data logging system can be downloaded into a personal computer by an RS232 cable and a software program. In evaluation stage, the performance of the developed penetrometer was compared with a commercial Eijkelkamp hand-pushed digital penetrometer in a controlled soil bin conditions. No significant difference was found (p<0.05) between the two penetrometers. The penetrometer performance was reliable and the penetrometer’s mechanical and electrical parts worked well without any malfunctions. The device is very light, easy to use and more economical compared to the conventional types.