THE EFFECTS OF ESTABLISHMENT METHODS AND FERTILIZATION PRACTICES ON NITRATE LEACHING FROM TURFGRASS

A lysimeter study was conducted at the Ohio State University Turfgrass Research Center, Columbus, to investigate NO3-N leaching losses from fertilized turfgrass. Nitrogen fertilizer treatments were applied to 'Baron' Kentucky bluegrass (Poa pratensis L.) seeded and sodded turf established on a Miamian silt loam (fine, mixed, mesic Typic Hapludalf). Treatments included two N sources, urea and resin-coated urea (RCU); and Two fertilization programs, one that emphasize spring and summer applications (SSF) and the second program that included a late season application (LSF). Both the SSF- and LSF-fertilization programs received 218.2 kg N ha-1 yr-1. The NO3-N leachate concentrations from seeded turfgrass exceeded those from sodded turf for the first 3 mon. As the turf matured, NO3-N losses from sod exceeded NO3-N from the seeded plots. Leachate concentrations were 1.1 and 3.5 mg NO3-N L-1 for seed and sod turf, respectively, from April 1990 through March 1991. Less rooting in the sodded plots resulted in greater N loss. Annual NO3-N losses were not affected by N source. During the winter of 1991, significantly (P = 0.05) higher percolate NO3-N concentrations were recorded from urea-treated plots (3.66 mg NO3-N L-1) vs. RCU (2.10 mg NO3-N L-1), however. Similarly, N programs did not result in annual differences in percolate concentration, but differed during the winter of 1991. Concentrations were 3.37 and 2.39 mg NO3-N L-1 for LSF and SSF, respectively. The NO3-N leaching losses from all treatments exceeded the maximum concentration limit (MCL) early in the study. These high concentrations were caused by soil disturbance during establishment. During the 2nd yr, NO3-N leaching results were more representative of typical turfgrass situations with mean annual flow-weighted NO3-N concentrations well below the MCL. Different N sources and fertilizer programs did not result in greater NO3-N percolate losses compared to unfertilized turfgrass plots.