WINDSOR, Va. (AP) _ The Virginia Department of Transportation is working to turn highway carcasses into plant food. The state agency is testing the practice of turning roadkill into compost at four sites across the state, using a special system that accelerates decomposition and suppresses odors. The Virginian-Pilot reports that the system costs $140,000 and can break down animals in as little as six weeks in concrete bins. The compost is then used to control erosion and help establish grass after construction. Officials say roadkill collected by the agency is traditionally buried or driven to landfills at a cost of $4 million per year for disposal. Several other states already have widespread programs to compost roadkill.