Using compost to encourage vegetation and limit erosion on mountain road cuts

Excerpt

Roads cut through mountainous regions often suffer from persistent and sometimes large-scale erosion. Soils derived from decomposed granite are generally thin. Road construction through these areas often results in many denuded cut and fill slopes (see figure 1). The sediment lost from these slopes may impair nearby water bodies. Construction regulations in these areas are becoming more stringent with respect to water quality concerns as well as slope stability. Efforts are currently underway to quantify the amount of sediment lost from road cuts in pristine areas such as Lake Tahoe, California, where total maximum daily loads are being set for roadways. Currently very little data are available to determine just how much sediment is being lost and what kind of reductions can be achieved using best management practices. To this end we attempted to quantify erosion from ambient and compost-amended treatments on a decomposed granite slope.

We constructed test plots at the base of a severely eroded 2:1 slope (run:rise) as seen in figure 2. In the compost-amended treatment, we incorporated 24% (by volume) municipal yard waste compost to a depth of 50 cm. This depth was chosen in order to be able to imbibe …