HARVEST MANAGEMENT AND N-FERTILIZATION EFFECTS ON PROTEIN YIELD, PROTEIN-CONTENT AND NITROGEN USE EFFICIENCY OF SMOOTH BROMEGRASS, CRESTED WHEATGRASS AND MEADOW BROMEGRASS

There is a lack of information on the interaction of harvest managemen t, grass species and N-ferlilizer interaction on forage quality and ni trogen use efficiency of dryland grasses. In a 3-yr field trial, harve st management (2 cut, hay management vs. a 3-4 cut simulated pasture m anagement system) and nitrogen fertilizer (0, 40, 80, 120, 160 kg N ha (-1)) were examined for their effects on protein yield (PY), protein c ontent (PC), nitrogen use efficiency (NUE), nitrogen recovery (NR) and soil test nitrate-nitrogen (STN) under crested wheatgrass (Agropyron cristatum [L.] Gaertn.; CWG), meadow bromegrass (Bromus biebersteinii Poem & Schult.; MBR) and smooth bromegrass (Bromus inermis L.; SBR) sw ards. Generally, grasses managed under a two-cut hay system had lower (P < 0.05) PC than grasses managed under a 3-4 cut simulated pasture s ystem land occasionally higher NR and NUE) but harvest management did not consistently affect PY. There were few consistent differences betw een grass species for PY, PC, NUE and NR with relative ranking and sig nificance changing between site-years. Generally, MBR responded to N-f ertilizer in a similar manner to previously studied dryland grasses su ch as CWG or SBR. N-fertilization increased PY and PC but did not cons istently affect NUE, NR and STN.