Tuesday, November 6, 2007 - 1:15 PM
191-2

Rate and Source of Nitrogen Effect on Yield and Quality of Stockpiled Fescue.

Elizabeth Yarber, Crop and Soil Environmental Sciences, Virginia Tech, Blacksburg, VA 24060, A. Ozzie Abaye, 245 Smyth Hall, Virginia Tech, Virginia Tech University, Dept. of Crop & Soil Environmental Science, Blacksburg, VA 24061, Marcus Alley, 416 Smyth Hall, Virginia Tech, Virginia Tech, Crop & Soil Environmental Science, Blacksburg, VA 24061-0403, C.D. Teutsch, Southern Piedmont AREC, Virginia Tech, 2375 Darvills Road, Blackstone, VA 23824, and G. Scaglia, Virginia Tech, 3080 Litton Reaves Hall, Blacksburg, VA 24060.

Nitrogen fertilization is a primary factor affecting the yield of stockpiled tall fescue. Nitrogen fertilizer costs have increased dramatically in the past year and availability of certain sources, i.e. ammonium nitrate, has become limited. Extensive research has considered the influence of N applied on yield, but the source of N has received relatively little attention. The objectives of this study were to evaluate the effects of N rate and source on the yield and quality of stockpiled tall fescue. Experiments were established in the Valley and Piedmont regions of Virginia to determine the effects on yield and quality of eight N sources applied at five rates. The sources included ammonium nitrate, ammonium sulfate, urea, urea with AgrotainŽ, a polymer coated urea (ESNŽ), a urea-based polymer, broiler litter, and pelleted biosolids applied at 0, 28, 56, 84, and 112 kg N-1. Applications were surfaced broadcasted in mid-August, and plots were harvested in mid-December/late-January. Significant interactions were observed between treatment and location, however no interactions were found between N rates x N source. Yield ranged from 1460 to 32560, 1910 to 3370, and 2920 to 3700 kg dry matter ha-1 for the three locations, respectively. Yields increased with increasing N rate at all locations. Yield increase per kg N applied differed between locations. Two locations showed similar rates of DM response per kg N applied (16.0 and 14.0 kg DM kg-1 N) while an increase of only 8.0 kg DM kg-1 N was observed at the third location. Rainfall patterns and amounts appear to explain most of the observations on yield response to N fertilization. Quality measurements on the forage are in progress. A second year of experiments is planned to develop a database for making N fertilizer source and rate recommendations for stockpiled tall fescue grazing systems.