Microclover and Compost As a Means of Reducing Lawn Fertilizer Use in the Chesapeake Bay Watershed.

The EPA estimates 8% of the total N load to the Chesapeake Bay watershed is from urban/suburban land, and an unknown portion of this is due to lawn fertilizers.  An interdisciplinary team from MD, PA, and VA is studying how planting microclover and incorporation of compost into soil can reduce N fertilizer needs and N loading from home lawns to the Chesapeake Bay.  The project began in 2012, and is being carried out at five sites in MD, PA, and VA.  Results are presented from experiments conducted at the University Park, PA site.  In Experiment 1, a yard-trimmings compost was incorporated into soil via tilling (509 m³ ha^-1), and planting a 95%/5% tall fescue/microclover mix at 294 kg ha^-1. In Experiment 2, compost was incorporated into an existing stand of tall fescue (64 m³ ha^-1), and microclover was inter-seeded into the tall fescue at 101 kg ha^-1. Plots in both experiments were split into two subplots, with half of each plot receiving no fertilizer and the other half receiving 49 kg ha^-1 yr^-1.  Compost tilled into soil increased infiltration and improved quality and ground cover during the first year of the study.  Microclover seeded into existing turf at 101 kg ha^-1 improved quality and color, but tended to dominate the stand.  Target groups for outreach activities include MD, PA, and VA extension educators, government entities, various builders associations, the Chesapeake Bay Foundation, and the US EPA’s Chesapeake Bay Program.  Workshop attendees participate in surveys that will gauge acceptance of compost use and microclover in lawns.