Ellen C. Knight, Auburn University Department of Agronomy and Soils, 201 Funchess Hall, Auburn University, AL 36849, C.W. Wood, Auburn University, Agronomy & Soils Dept., 202 Funchess Hall, Auburn Universtiy, AL 36849-5412, and Elizabeth Guertal, Auburn Univ.-Agron.& Soils Dep, 202 Funchess Hall, Auburn, AL 36849-5412.
Few studies have addressed ammonia (NH3) volatilization from coated fertilizers applied to turfgrasses in the field. The objective of this study was to determine the amount of nitrogen (N) lost through NH3 volatilization from three N sources applied to existing turfgrass stands. Treatments were applied to Tifway hybrid bermudagrass, Emerald zoysiagrass, and both bermudagrass and zoysiagrass in fall 2005, spring 2006, and fall 2006, respectively, near Tuskegee, AL. Fertilizer treatments included: urea (46 g kg-1 N), methylene urea (40g kg-1 N), and polymer-coated urea (41g kg-1 N). Ammonia was captured using a passive micrometeorological system and differences in N sources were observed over a 10 day period. In 2005, urea released the highest proportion of applied N (11.7 %). The mass of NH3 released from methylene urea (7.4 %) was not different from the amount released from urea at P ≤ 0.10. Polymer-coat urea differed from urea in the amount of NH3 volatilized, but did not differ from methylene urea at P ≤ 0.10. In spring 2006, NH3 volatilization from N sources was in order of urea (20.1%) > methylene urea (7.4%) > polymer-coated urea (4.4%) (P≤ 0.10). Nitrogen sources followed the same trend in fall 2006: urea (15.7%) > methylene urea (4.2%) = polymer-coated urea (4.4%) (P < 0.10). Urea releases a greater proportion of N applied than the slow-release sources methylene urea and polymer-coated urea. Polymer-coated urea appears to be superior to methylene urea as a slow-release N source the first 10 days after application.
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