|King, Larry - WASHINGTON STATE UNIV|
|Gatto, Lawrence - US ARMY CORPS OF ENG|
Submitted to: Terramechanics Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: January 1, 2001
Publication Date: June 1, 2001
Citation: HALVORSON, J.J., MCCOOL, D.K., KING, L.G., GATTO, L.W. SOIL COMPACTION AND OVER-WINTER CHANGES TO TRACKED-VEHICLE RUTS. TERRAMECHANICS JOURNAL 38 (2001( 133-151. Interpretive Summary: Compaction from heavy vehicles such as military tanks can adversely affect water infiltration and soil erosion. There is need to predict and minimize these impacts on US Army training centers. Research was conducted jointly by USDA-ARS, Washington State University, and the Dept. of Defense Cold Regions Research and Engineering Laboratory and the Yakima Training Center in central Washington to determine the effects of over-winter change on physical characteristics of tank ruts such as bulk density and hydraulic conductivity. Over-winter changes were mainly limited to the upper 2.5 cm of the soil. Over-winter changes were not evident deeper in the soil. Moisture content at the time of tracking influenced physical characteristics of the ruts. Less compaction occurred when traffic occurred on dry soil. In order to prevent environmental degradation, traffic on wet soils should be avoided. Recovery of compaction damage is slow below 2.5-cm depth.
Technical Abstract: We monitored two experimental areas at the Yakima Training Center (YTC) in central Washington to measure changes to M1A2 Abrams (M1) tank-rut surface geometry and in- and out-of rut saturated hydraulic conductivity (Kfs), soil penetration resistance (SPR) and soil bulk density (BD). Profile meter data show that rut cross-sectional profiles smoothed significantly and that turning ruts smoothed more than straight ruts. Rut edges were zones of erosion and sidewall bases were zones of deposition. Kfs values were similar in and out of ruts formed on soil with 0-5% water by volume, but were lower in ruts formed on soil with about 15% water. Mean SPR was similar in and out of ruts from 0-5-cm depth, increased to 2 Mpa outside ruts and 4 Mpa inside ruts at 10-15-cm depth, and decreased by 10-38% outside ruts and by 39-48% inside ruts at the 30-cm depth. Soil BD was similar in and out of ruts from 0- to 2.5-cm depth, and below 2.5 cm, it was generally higher in ruts formed on moist soil. Highest values occurred between 10- and 20-cm depth. Conversely, BD in ruts formed on dry soil was similar to out-of-rut BD at all depths. This information is important for determining impacts of tank ruts on water infiltration and soil erosion and for modifying the Revised Universal Soil Loss Equation and the Water Prediction Models to more accurately predict soil losses on Army training lands.