Influence of Nitrogen Source On Nitrate-Nitrogen Leaching When Applied to Centipedegrass and St. Augustinegrass.

The increasing concern about the effects that lawn and landscape management practices have on natural water resources in Florida resulted in the development of Best Management Practices (BMP’s) for the Green Industries in an attempt to mitigate any potential nonpoint source pollution of water resources.  There was a need to quantify nutrient loading from these practices under different conditions to verify the current recommended rates of nitrogen (N) for use on turfgrass species throughout Florida.  The objectives of this research were to evaluate various nitrogen sources on nitrate-N leaching in St. Augustinegrass and Centipedegrass and corresponding turfgrass response. This study was conducted from 2008 to 2011 in Jay, FL.  Seven N source treatments included untreated control, low control (ammonium nitrate), quick released/high control (urea), 30% slow release nitrogen (SRN), 50% SRN, polymer coated nitrogen (PCU) applied twice at 49 kg ha^-1 or once at 98 kg ha^-1, and an organic product biosolid. Nitrogen import appeared to negate N-source treatment differences in the inaugural year.  Differences in nitrate-N leaching were observed over time and were generally related to 1.) Species (St. Augustinegrass generally leached more N than Centipedegrass); 2.) N source (soluble sources leached more N than insoluble sources); and 3.) Turf cover (damaged turf leached more N than healthy turf).