SPRING NITROGEN APPLICATION - EFFECTS ON YIELD AND QUALITY OF BARLEY SILAGE

The effects of intensive agronomic management systems on yields and quality of barley (Hordeum vulgare L.) silage were examined. Nitrogen treatments included combinations of the rate and timing of application. Nitrogen was applied at 80 or 120 lb/acre either as a single application or split between Zadoks growth stage (GS) 25 and 30 (tillering and prejointing, respectively). Forages were harvested and ensiled and 30 crossbred wethers were utilized to determine voluntary intake and utilization of the silage produced. Forage dry matter (DM) yields increased (P < 0.01) with all N additions. Highest DM yields (3.65 t/acre) were achieved utilizing split N applications. Crude protein content of forage was increased as the rate of N application was increased. The greatest response was at GS 30. Crude protein content of the silages ranged from 8.3% without N fertilization to 12.8% with 120 lb N/acre at GS 30. All silages preserved well. Silage pH was lowest for controls and similar among N treatments. Intake of silage DM by sheep was higher (P < 0.01) when the silage was from plots which had been fertilized with N than when it was from unfertilized plots. Intake of silage DM was similar among silages produced from N fertilized plots. Higher (P < 0.01) DM, crude protein, neutral detergent fiber and acid detergent fiber digestibilities were observed in silages produced from barley which was fertilized with N. Dry matter and crude protein digestibility were increased (P < 0.02) as the rate of N application was increased from 80 to 120 lb/acre.