Using Compost to Increase Infiltration and Improve the Revegetation of a Decomposed Granite Roadcut

Decomposed granite (DG) soils are very erosive and, when disturbed, are difficult to revegetate. Sediment eroding from DG roadcuts can severely impact nearby drainage basins. Two ways of reducing surface erosion are to increase the surface saturated hydraulic conductivity (Ksat) of the soil and to stabilize the surface with vegetation. This study examined the ability of unscreened yard waste compost to increase the Ksat of these soils and facilitate revegetation. A compost application rate of 24% by volume increased postconstruction Ksat of a DG roadcut to levels comparable to a revegetated reference site. The establishment of vegetation was important to maintain the initial increase in Ksat associated with tillage and compost amendment. By the second year, above-ground biomass significantly increased with increasing compost amendment rate. There was also a significant increase in soil Ksat in the 12 and 24% compost treatments in the second year compared to the first year, indicating the strong influence of plant growth on soil surface hydrology.