Bernard Gagnon, Noura Ziadi, Gilles Bélanger, Gaétan Parent
Agriculture and Agri-Food Canada, 2560 Hochelaga Blvd, Quebec, QC, Canada, G1V 2J3, bernard.gagnon@agr.gc.ca
Abstract
Nitrogen fertilization is essential for forage grass production but little information exists on the efficiency of different mineral N fertilizers available in eastern Canada. We assessed the benefits of using different urea-based fertilizers in timothy (Phleum pratense L.), the main forage grass species used in eastern Canada. We compared, during two growing seasons (2014-2015), polymer-coated controlled release urea (PCU), blend of 50% PCU:50% urea, and urea treated with an inhibitor of urease (Urea + NBPT) broadcast at early spring to calcium ammonium nitrate (CAN) broadcast at early spring (60%) and after the first cut (40%). Each N fertilizer was added at rates of 50, 100, 150 and 200 kg N ha-1. A control with no applied N was included. The three enhanced-efficiency N fertilizers produced similar annual forage yields than CAN in both years. Yield distribution by cut, however, was significantly affected by the fertilizers. The highest yield was achieved with the blend PCU:Urea and Urea + NBPT at the first cut, and with PCU at the second cut. The soil nitrate content after the first cut was highest with PCU:Urea and Urea + NBPT, but in the fall it was low and not affected by fertilizers. Forage total N and nitrate concentrations were also highest in the first cut with the application of Urea + NBPT whereas PCU mostly increased forage N in the second cut. Urea management options are recommended as alternative to CAN under the climatic conditions of eastern Canada.