Mechanical assist devices for operating hand-held soil penetrometers using operator’s static body weight as an anchoring force

Authors: Iversen, William; Stevens, William; Jabro, Jalal

Submitted to: Applied Sciences
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/2/2026
Publication Date: 7/7/2026
Citation: Iversen, W.M., Stevens, W.B., Jabro, J.D. 2026. Mechanical assist devices for operating hand-held soil penetrometers using operator’s static body weight as an anchoring force. Applied Sciences. 16(3). Article 6807. https://doi.org/10.3390/app16136807.
DOI: https://doi.org/10.3390/app16136807

Interpretive Summary: Measuring soil compaction is important to understand the impact of tillage, crop type and rotation, wheel traffic, freeze/thaw cycles and other variables on soil density. Soil compaction reduces yield by reducing the volume of soil that plant roots can explore. It is difficult to determine the best management practices if the compaction can’t be easily measured. Portable soil compaction meters (soil penetrometers) have been available for many years, but they all suffer from several short comings. They rely on the operator to push on a T-handle to force the tip of the device into the soil at a constant rate. This is difficult to do, as the probe will push easier in soft soil than in a hard compacted layer, so the human operator has a difficult time maintaining a steady insertion rate, particularly as body posture changes. That change in rate causes inaccurate measurements. A commonly used model does warn the user that the rate is incorrect, and it will take often several tries to get a single valid record in tough conditions. A second shortcoming of the available products is that they cannot be used where a rough soil surface, high residue, or plants are present. If any of these conditions exist the residue or crop must be removed or the soil smoothed and a metal plate laid on the surface for an accurate reading. A third issue is that the ultrasonic sensor used to measure the depth of the probe cannot be used in windy conditions. The design presented in this manuscript solves all of these problems and still maintains the portability of the currently available devices.

Technical Abstract: Operation of handheld soil penetrometers can cause physical strain and ergonomic discomfort to the operator, especially with repeated use in difficult soil conditions. Three embodiments of mechanically assisted penetrometers that use the operator’s static body weight as an anchoring force were designed and evaluated for their effectiveness in reducing operator strain while maintaining or improving the accuracy of penetration resistance measurements compared to a commercially available, manually operated device. Bipod and Tripod embodiments utilized an electrical linear actuator to provide mechanical assistance for inserting the commercially available penetrometer rod into and retracting it from the soil. The Iversen monopod embodiment was designed and constructed using readily available structural and electronic components in a novel configuration that incorporates a linear actuator for mechanical assistance, a potentiometer for depth measurement and base plate upon which the operator can stand to anchor the device. The use of the potentiometer in combination with the base plate and vertical structure enabled it to be used in high residue conditions, under crop canopy and in windy conditions where the commercially available units fail. All three embodiments resulted in reduced physical and ergonomic strain and provided improved data quality. It was concluded that the Iversen monopod is the preferred design due to its superior depth measurement accuracy, elimination of incorrect insertion rate errors and the reduced physical and ergonomic strain experienced by the operator.