Impacts of Compost Application on Highway Construction Sites in Iowa

Runoff, interrill erosion, and growth of erosion control vegetation and weeds were measured on conventionally treated portions (control) of newly constructed roadway embankments, and on areas pretreated with topsoil or one of three different types of composted organics. Runoff rates and interrill erosion rates from the control and topsoil-treated plots were highest. Runoff rates from the three compost media (biosolids, yard waste, bio-industrial waste) used were statistically lower than the control. Runoff from plots treated with yard waste and bio-industrial waste composts were statistically lower from plots treated with topsoil. Interrill erosion rates from topsoil-treated plots were significantly higher than from compost-treated or control plots. The amounts of planted cover crop grown on all treatments were statistically indistinguishable. Mean values for weed growth on the control and topsoil plots are statistically indistinguishable, and all compost treatments except biosolids-10 cm and yard waste-5 cm produced significantly lower weed growth than either the topsoil or control plots