Nitrogen fertilizer product and timing alternatives exist for forage production in the Peace region of Alberta

Karamanos, R. E. and Stevenson, F. C. 2013. Nitrogen fertilizer product and timing alternatives exist for forage production in the Peace region of Alberta. Can. J. Plant Sci. 93: 151-160. Four different N sources [ammonium nitrate (NIT), urea (UR), polymer-coated urea (PCU), and N-(n-butyl) thiophosphoric triamide-treated urea (AGR)] were applied to stands of pure meadow bromegrass (Bromus beibersteinii L.) or a 50:50 smooth bromegrass (Bromus inermis L.)-alfalfa (Medicago sativa L.) mixture in late fall and early spring at four N rates (0, 60, 80 and 100 kg N ha-1) over a 3-yr (2003-2005) period. The N treatments generally increased forage responses, but the response net revenue to N treatment was rarely positive and at times was negative, especially for PCU. On average, PCU resulted in lower yield and protein concentration, lesser N efficiency, and lesser profit relative to other forms of N. This difference was more pronounced in the spring and was less notable at Rycroft, the location with the bromegrass-alfalfa mixture. Also, greater N fertilizer rates increased the yield, protein concentration, total N uptake, and profit for all fertilizer forms. The exceptions to the preceding were N fertilizer rate did not affect forage responses for PCU and at the location with the brome-alfalfa mixture. Urea or AGR provided satisfactory agronomic alternatives to ammonium nitrate when applied in early spring at sufficient rates.