Impacts of Off-Road Vehicles on Infiltration and Sediment Production of Two Desert Soils

Abstract

Impacts of motorcycle and 4-wheel drive truck traffic on infiltration rate and sediment production were evaluated on two desert soils. Infiltration was similar for both soils; however, more sediment was produced from a surface with exposed mineral soil than from a gravel-mulched surface. Infiltration was 3 to 13 times greater on the coppice soil beneath shrubs than on interspace soil between shrubs, but sedimentation was 10 to 20 times greater on interspace soil. Infiltration was less and sediment yield was greater after soil was disturbed by vehicular traffic, and after reformation of the surface crust, particularly on interspace soil. High sediment production from interspace soil was attributed to reduced infiltration after 10 minutes. The soil then became saturated and unstable, was dispersed by raindrop impact, and particles were carried in runoff water for the remaining 20 minutes of the test period. Coppice soil had a high infiltration rate for the entire test period and did not become saturated. In addition, the high organic matter and aggregate stability of coppice soil prevented soil movement, though some runoff occurred.