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ARS Home » Pacific West Area » Pullman, Washington » Northwest Sustainable Agroecosystems Research » Research » Publications at this Location » Publication #96246
Title: GROUND FREEZING EFFECTS ON SOIL EROSION OF ARMY TRAINING LANDS PART 2: OVERWINTER CHANGES TO TRACKED-VEHICLE RUTS, YAKIMA TRAINING CENTER, WASHINGTON

Author
item HALVORSON, J - WASHINGTON STATE UNIV.
item McCool, Donald
item KING, L - WASHINGTON STATE UNIV.
item GATTO, L - U.S. ARMY

Submitted to: Cold Regions Research Engineering Laboratory Special Report
Publication Type: Government Publication
Publication Acceptance Date: 4/1/1998
Publication Date: N/A
Citation: N/A

Interpretive Summary: Compaction from heavy vehicles such as military tanks can adversely effect 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 at the Cold Region Research Laboratory and the Yakima Training Center in central Washington to determine 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 change was not evident deeper in the soil. Moisture content at 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 a 2.5 cm depth.

Technical Abstract: We monitored two experimental areas at the Yakima Training Center (YTC) in central Washington to measure over-winter changes to tank-rut profiles, soil saturated hydraulic conductivity (Kfs), soil penetration resistance (SPR) and soil bulk density during the winter of 1995-1996. Average tank- rut geometry changed significantly from fall to summer in YTC silt-loam soils. During this period, the average standard deviation of 1.8 meter cross-sectional profiles of tank ruts decreased significantly indicating that the profiles were smoothing. The effect of tank compaction on Kfs of silt-loam soils at YTC is a function of soil water content at the time of tracking. We observed similar Kfs in and out of ruts for tracks formed on soil with 0-5% moisture by volume (dry) but lower Kfs in ruts when tracks were formed on soil containing about 15% moisture by volume (moist). Mean SPR was low and similar in and out of ruts near the surface (0-5 cm depth). .Mean SPR increased with depth to a maximum of about 2 MPa outside ruts and 4 MPa inside ruts at 10-15 cm, and then decreased with greater depth. Soil bulk density was similar in and out of ruts near the soil surface (0-2.5 cm depth). Below 2.5 cm, the soil bulk density was generally higher in ruts where tracks had initially been formed on moist soil. The data suggest the surface 2.5 cm of soil is less compacted by tank traffic than deeper in the profile or, alternatively, that initial surface compaction does not persist over winter. This information is important for determining impacts of tank ruts on water infiltration and soil erosion, and can be used in soil erosion models such as the Revised Universal Soil Loss Equation and the Water Erosion Prediction Project to more accurately predict soil losses on Army lands in cold climates.