Optimizing Unfertilized Buffer Strip Distances to Reduce Nitrogen Transport.

Numerous regulations and ordinances have recently been enacted in Florida in an attempt to reduce fertilizer runoff from turfgrass systems.  In most cases, these include restrictions placed on the distance from the edge of a body of water that must remain unfertilized.  However, the optimal unfertilized width that will minimize movement of fertilizers and nutrients to the body of water has yet to be well determined.  A field study was conducted to quantify nitrogen (N) transport and to evaluate the effective size of an untreated buffer strip or “ring of responsibility” located adjacent to a water body. On two  dates; Three N containing fertilizers were evaluated and included: 1.) ammonium sulfate (AS); 2.) polymer coated urea (PCU); and 3.) urea formaldehyde (UF). Each 48 kg ha^-1 fertilizer treatment was placed on a 7% slope on a ‘Tifway’ hybrid bermudagrass (Cynodon Dactylon x C. transvaalensis)  fairway at four separate distances above a collection weir (0, 0.9, 1.8, and 3.6 m). Simulated runoff was provided with a 46mm hour^-1 irrigation event. Runoff samples were collected immediately following treatment and analyzed for total soluble nitrogen (TSN).  Nitrogen loads were evaluated to determine the influence of the size of an untreated buffer strip had on nutrient and fertilizer movement during runoff events. Runoff losses from AS were comparable regardless of fertilizer placement.  UF was influenced by upslope placement with greater losses occurring near the water body.  Runoff losses from PCU, regardless of slope placement, were negligible.