contributed by Karen Colson and Jason Karl
Soil Properties – Quantitative
Description and Uses
The impacts of soil compaction, such as reduced water infiltration, increased runoff potential, limited root growth and microorganism activity, and ultimately reduced site potential, are well known. But reliable methods to measure compaction are limited. There are three commonly used techniques for assessing soil compaction: strain gauge penetrometer, impact penetrometer and bulk density.
An impact penetrometer is one method that can be used to help determine whether or not a soil is currently compacted. This method however requires reference data for similar soils with the same moisture content for comparison. In general, soil compaction is determined by the work needed to push a penetrometer cone into the soil with successive blows. See Herrick et al. 2002 for a more detailed description of this technique and information on constructing a penetrometer.
Advantages and Limitations
Cost, measurement reliability, and difficulty in comparing data can all be concerns when using penetrometers. Penetrometer measurements, for example, are very sensitive to soil moisture and measurements can only be compared among years if soil moisture content is the same during each sampling period. In addition, the repeatability of the measurements depends on the consistency of the height from which the mass is dropped.
Technical and Application References
- Herrick, J.E. and T.L. Jones. 2002. A dynamic cone penetrometer for measuring soil penetration resistance. Soil Science Society of America Journal 66: 1320-1324. http://jornada.nmsu.edu/sites/jornada.nmsu.edu/files/HerrickJones2002Penetrometer.pdf
- Pellant, M., P. Shaver, D.A. Pyke, and J.E. Herrick. 2000. Interpreting indicators of rangeland health, version 3. Technical Reference 1734-6. USDI, BLM, National Sci. and Tech. Center, Denver, Colo. 21-Mar-02. http://www.blm.gov/nstc/library/pdf/1734-6.pdf
Qualitative methods (Pellant et al. 2000) are also useful for determining if soil is compacted. Some indicators, not related to a texture change, include platy soil structure and abrupt changes in root growth patterns.
Printable data forms for the soil compaction method can be downloaded from
Electronic data forms can be found at the following sites
- Soil compaction data can be recorded directly into the Rangeland Database in the field.
- An Excel version of the soil compaction method data form that automatically calculates cover percentages can be found at the Jornada Experimental Range Monitoring and Assessment Site.
- An version of the soil compaction Excel form that is compatible with electronic PDAs can also be downloaded from the Jornada Experimental Range Monitoring and Assessment Site
Soil stability kits and impact penetrometers can be purchased from the following vendors: