Nitrate Leaching, Turf Quality, and Growth Rate of 'Floratam' St. Augustinegrass and Common Centipedegrass

Turf fertilization in Florida continues to be viewed as contributing to nonpoint-source pollution of ground water. Continued research is needed to validate existing best management practices (BMPs). The objectives of this research were to evaluate nitrate-N (NO3-N) leaching, turf quality, and turf growth rate from N sources applied to 'Floratam' St. Augustine grass [Stenotaphrum secundatum (Walter) Kuntze] and common centipede grass [Eremochloa ophiuroides (Munro) Hack.]. Research was conducted in Jay, FL, from 2008 to 2011. Nitrogen was applied in 60-d cycles at 48 kg ha(-1) as ammonium nitrate, urea, 30% slow-release N (SRN), 50% SRN, polymer-coated urea (PCU), and biosolid (BS) and in 120-d cycles at 98 kg ha(-1) as PCU. Nitrogen leaching was greatest during the first 6 mo following turf sodding for both species with 21.6 and 10.1 kg ha(-1) leached from St. Augustinegrass and centipedegrass, respectively. Following sodding, no differences in N leached between turfgrasses were observed until 2010 when winter-kill and large patch (Rhizoctonia solani Kuhn) were observed on St. Augustinegrass. Turf quality of control plots was above acceptable levels in 2008 but was unacceptable by 2011. Each N source produced acceptable centipedegrass with few differences among N sources. A blend of 50% ammonium sulfate and 50% PCU resulted in higher growth rates and turf quality of St. Augustinegrass than other N sources in most years. Recommending N applications to newly sodded turf may not be necessary due to the risk of leaching during establishment.