Comparison of Sulfur-coated Urea and Ammonium Nitrate as Fertilizers for Pensacola Bahiagrass on a Spodosol1
- W. G. Blue2
Two slowly available experimental sulfur-coated urea (SCU) materials produced by the Tennessee Valley Authority were compared with ammonium nitrate as N sources for ‘Pensacola’ bahiagrass (Paspalum notatum Flugge) on Myakka fine sand (sandy, siliceous, hyperthermic Aeric Haplaquod). One of the SCU materials contained 35.4% N with a S coating of 23% while the other contained 40.2% N with a 12.6% coating which included S plus 2% diatomaceous earth and 0.25% coal tar. Four levels of N (0, 112, 224, and 336 kg/ha) were applied annually for 3 years to an established grass sod which had not been fertilized with N during the previous 2 years. Ammonium nitrate was applied in single and split applications, and the SCU materials were applied in single annual applications. Single applications were made in late March of each year. For the split applications of ammonium nitrate, one-half was applied in late March and one-half approximately 1 July. Forage growth increased with each level of N from all sources. Nitrogen utilization efficiency was higher (67%) from the 224- and 336-kg/ha N rates than from the 112-kg/ha rate (57%). Forage yield increase from the SCU (35.4% N) material was relatively poor the first year; pellets of this material were found consistently in the grass thatch at the soil surface 1 year after application. However, forage yields and N contents for each N rate over the 3-year comparison period were not affected by N source or number of applications. The residual effect of SCU materials during the fourth year as measured by N content of forage ranged from 2 to 7% of the total N applied. These quantities of N were generally less than the decline in N content of the stolon-root system. Forage production and N content distribution with time were not drastically altered by these slow release materials compared with ammonium nitrate.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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