ARS | Publication request: A DYNAMIC CONE PENETROMETER FOR MEASURING SOIL PENETRATION RESISTANCE

Submitted to: Soil Science Society of America Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: December 6, 2001
Publication Date: July 1, 2002
Citation: HERRICK, J.E., JONES, T.A. A DYNAMIC CONE PENETROMETER FOR MEASURING SOIL PENETRATION RESISTANCE. SOIL SCIENCE SOCIETY OF AMERICA JOURNAL. 2002. V. 66(4). P. 1320-1324.

Interpretive Summary: Soil compaction is a major problem affecting both croplands, pastures, and occasionally rangelands. Reducing compaction is expensive, so methods are needed to accurately measure where compaction occurs and how fast it is changing. There are a number of methods for measuring changes in compaction, but suffer from at least one of the following limitations: they yare expensive, subject to operator error or cannot be used on extremely compacted soils. We developed a simple penetrometer which can be used by anyone, regardless of technical knowledge or strength, to monitor compaction changes for soils of any density. Like any penetrometer, measurements must be made at the same moisture content. The penetrometer can be constructed by a machine shop for less than $150 and consists of a cone-tipped rod topped by a strike plate, a shaft extension and a hammer that slides on the shaft. The penetrometer cone is pushed into the soil by successive hammer blows. The number of hammer blows needed to push the con into the soil to a pre-selected depth is related to the level of compaction. This penetrometer can be used by farmers, ranchers and organizations involved in restoration and reclamation work to improve their ability to identify and manage areas where soil compaction is a problem.

Technical Abstract: Recognition of the importance of soil compaction is increasing, but instrument cost, measurement repeatability and data interpretation limit its measurement on agricultural and rangelands. The dynamic penetrometer described here follows ASAE standards but replaces the proving ring with a strike plate, a shaft extension and a sliding hammer. The penetrometer cone eis pushed into the soil by successive hammer blows. Penetration resistance is calculated as the work by the soil needed to stop cone movement divided by the penetration distance. The work by the soil is defined as the kinetic energy of the hammer when it impacts the strike plate. Construction cost is approximately US$100. The standard drop height and hammer mass ensure measurements are consistent between operators.