Nitrate Leaching As Affected by Soil Type and Controlled Release or Modified N Sources.

Although nitrogen (N) leaching studies are plentiful in the turfgrass literature, newer controlled and/or ‘stabilized’ N release technologies require continued study to examine the impact of these new products on N loss from turfgrass. The objective was to examine N loss from small-scale leachate collection chambers as affected by N source and soil type. The two-year study was conducted small scale (1 m x ½ m) leachate collection chambers. In 2008, each of 16 units was filled with the soil types: 1) Marvyn loamy sand, 2) washed sand, and, 3) Sumter clay. The same soil and bins were used in 2008 and 2009. Fertilizers: 1) Urea (46-0-0), 2) UMaxx® (47-0-0), 3) Polyon® (43-0-0), and, 4) an unfertilized control. Fertilizers were applied at 7.3 g m-2 in July of each year. In each week: 1) leachate volume was determined, 2) a leachate subsample was analyzed for nitrate, ammonium and urea, and, 3) a soil sample was analyzed for soil nitrate and ammonium. In the Sumter soil, nitrate-N or ammonium-N in leachate was unaffected by fertilizer source. In the sand and Marvyn loamy sand the trend for nitrate-N in leachate was in the order (from most to least): Urea = UMaxx > Polyon > urea. In the sand plots total nitrate-N leached from urea-plots was significantly greater than that measured in the unfertilized plots, while total nitrate-N leached from the Polyon or UMaxx fertilized plots was not significantly greater than that measured in the control. Cumulative urea-N leached was typically low.