Effects of soil bulk density and water content on penetration resistance

Infrastructure installation (e.g., pipelines) disturbs soils, often resulting in increased soil compaction (bulk density [Bd] and penetration resistance [PR]). The relationship of PR to Bd, gravimetric water content (Theta g), and a suite of other properties were determined on seven topsoils to provide a model and database for reclamation specialists to use when assessing disturbed soils. Penetration resistance had a strong linear association with Bd, but higher Theta g reduced the range of PR as Bd increased. Step-wise regression identified Bd, Theta g, texture, clay speciation, and organic matter as significant factors to predict PR. The model predicts PR from <1 to 8 MPa and closely match measured values. Soil Bd and Theta g contributed to 84% of the model's explained variation in predicting PR. This study provides a tool for reclamation specialists that aids in understanding the risks associated with disturbances and highlights the importance of keeping Theta g low during installation of pipelines.