Primary and Residual Effects of Abrams Tank Traffic on Prairie Soil Properties

Mechanized maneuver training can impact soil quality in many ways, most notably through soil displacement and compaction. To identify indicator variables for inclusion in monitoring programs on military lands, a replicated small-plot study of tracked vehicle disturbance effects on tallgrass prairie soil properties was initiated on Fort Riley, KS, in 2003. A range of disturbances encompassing soil surface texture, environmental conditions, and traffic intensity were evaluated. Soil physical (rutting and compaction) and chemical (soil organic matter and nutrients) properties were monitored annually on curve and straightaway track areas through 2007. Rut depth remained significant (P <= 0.05) for curves of inside and outside tracks in both soil surface textures throughout the study and was more severe for repeated vs. single traffic events. Bulk density increased with disturbance under wet soil conditions, repeated traffic, and on curve areas but recovered to undisturbed levels within 1 to 3 yr. Soil compaction as measured by penetrometer resistance was more severe for traffic under wet soil conditions and remained significant (P <= 0.05) at depths of 5 to 10 cm in both soil surface textures throughout the study. Residual effects of tank traffic on soil chemical properties were generally mild, but soil C was reduced following disturbance under wet soil conditions, repeated traffic, and on curve areas and required 3 to 4 yr to recover to undisturbed levels. The results of this study emphasize the importance of suitable impact management to maintain the sustainability of tallgrass prairie for military training activities.