Comparison of Compost and Hydromulch for Stabilization of Disturbed Sites

Construction projects often expose large amounts of soil to the erosive forces of wind and rain. These areas must be stabilized and vegetation established before a Notice of Termination can be submitted to regulators. Quarries face many of the same issues with regard to stabilization of spoil piles and areas disturbed by mining. The objectives of this project were to compare the stabilization performance of two types of compost top dressing (low and high organic matter), a wood based hydromulch, and seeded bare soil and to determine the amount of sediment and nutrients exported from each type of treatment. Ten test plots (8 feet x 40 feet) were constructed on a spoil pile of a quarry located in Parker County, Texas. These plots were outfitted with runoff capture systems to collect all runoff from each plot. Water quality and quantity data were collected for 10 storms during the first year after installation. Compost mixtures were most successful at establishing vegetation, with almost full coverage after about four months. The hydromulch plots took much longer, with full establishment taking almost a year. The seeded bare soil plots had little vegetation even after a year. Runoff coefficients for the two types of compost were similar and about half that observed for the hydromulch and control plots, which were not significantly different. Compost reduced sediment discharge compared to bare plots by about 97%. The hydromulch was less effective than the compost treatments, but still reduced the TSS load by about 75% compared to bare plots. Even though both treatments reduced the load of total phosphorus discharged, dissolved phosphorus loads from compost treated plots were higher than from bare soil or hydromulch plots.