Unfertilized Buffer Strips and Their Influence On Nitrogen Movement Following Excessive Precipitation.

Numerous regulations and ordinances have recently been enacted 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 be left unfertilized. However, the optimal width that will minimize movement of fertilizer sources and nutrients to nearby bodies of water has not been determined. A worst case scenario field study was conducted to quantify nitrogen transport and evaluate the effective size of an untreated buffer strip or ring of responsibility located adjacent to a body of water. Three nitrogen fertilizers were evaluated and included: 1.) ammonium sulfate; 2.) polymer-coated urea; and 3.) ureaformaldehyde. 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 interval distances (0,.9,1.8, and 3.6 m). Runoff was forced with a 46 mm hr^-1 precipitation event immediately following fertilization. Runoff samples were collected systematically after treatment and analyzed for Total Soluble Nitrogen (Antek 9000N Series analyzer). TSN loads were evaluated to determine fertilizer formulation and the appropriate size of an untreated buffer strip. TSN loads were significantly affected by fertilizer formulation with the highest loads occurring from the soluble source ammonium sulfate (4.13 mg TSN L^-1) > ureaformaldehyde (1.04 mg TSN L^-1) > polymer-coated urea (.06 mg NO₃-N L^-1) = control (.02 mg NO₃-N L^-1). In addition the average mg TSN L^-1 under ureaformaldehyde was reduced by an adjusted quantity of .26 to .75 mg TSN L^-1 when a 3.6 m buffer was used rather than 1.8 m.