Evaluation of bulk density and vegetation as affected by military vehicle traffic at Fort Riley, Kansas

Authors: Retta, Amare; Wagner, Larry; Tatarko, John; TODD, TIMOTHY - Kansas State University

Submitted to: Transactions of the ASABE
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/28/2012
Publication Date: 3/1/2013
Citation: Retta, A., Wagner, L.E., Tatarko, J., Todd, T. 2013. Evaluation of bulk density and vegetation as affected by military vehicle traffic at Fort Riley, Kansas. Transactions of the ASABE. 56(2):653-665.

Interpretive Summary: Field experiments were conducted at Fort Riley, using an M1A1 Abrams tank and a Humvee. Experimental plots were subjected to repeat trafficking by both vehicles. Soil compaction and vegetation loss data were collected, and analyzed using appropriate statistical procedures. The results of the data analysis showed that soil compaction under the M1A1 tracks was detected up to 15 cm depth; under the Humvee soil compaction was relatively small. Vegetative cover loss was similar for both vehicles. Loss of standing biomass was much more severe under the M1A1 tracks than the Humvee tracks. The results of this investigation, in conjunction with similar data from experiments that are planned at various military bases across the U.S.A., will allow the development of appropriate relationships that can be incorporated in WEPS (Wind Erosion Prediction System) model so that the model can be used to aid in evaluating military training programs that minimize adverse impacts on the environment.

Technical Abstract: Studies were conducted using military vehicles to determine the influence of repeated traffic on soil compaction and vegetative losses. These data will eventually be incorporated into models such as the Wind Erosion Prediction System (WEPS). A replicated field experiment was conducted in the fall of 2010 on two soils that dominate the military training grounds at Fort Riley, Kansas. Treatments consisted of two vehicle types, and three levels of vehicle passes. We used an Abrams M1A1 tank and a High Mobility Multipurpose Wheeled Vehicle (i.e., Humvee), representing tracked and wheeled military vehicles, respectively. Bulk density, above ground standing biomass, and plant cover were measured before and after vehicular traffic in the fall of 2010 as well as in the spring and summer of 2011. Samples were taken from curved, straight, and cross-over sections of the vehicle tracks. A mixed-model analysis of variance of the data indicates that the overall mean bulk density under the M1A1 was significantly greater than under the Humvee (p=0.05). In general, as the number of passes increased the bulk density under the M1A1 increased significantly (p=0.05), but the increases under the Humvee were not significant (p=0.05). Bulk densities were significantly greater in the curved part of the tracks than the straight part of the track. Reduction in standing biomass and vegetation cover was more severe on average under the M1A1 than under the Humvee (although not significant at p=0.05). For both vehicles, biomass and cover were affected more at the curved sections of the track than the straight sections (significant at p=0.05). Comparison of spring and fall bulk density data showed significant differences at the 0-5 cm and 5-10 cm depths; indicating that the winter freeze and thaw cycles loosened the top soil layers. Subsequent growth showed severe reduction in grass biomass growth at the curved sections of the tracked vehicle paths. Growth in forb species was not significantly affected.