Effects of Nitrogen Application on Barley, Oats and Triticale Grown as Forage

A 3-yr study was conducted to determine the effects of high rates of N fertilizer (NH 4 NO 3 ) on whole plant dry matter yields, crude protein and NO 3 -N concentrations and in vitro digestibility of dry matter of oats (Avena sativa L.), barley (Hordeum vulgare L.) and triticale (X Triticosecale Wittmack) harvested at early dough stage. Dry matter (DM) yields of barley only were significantly increased by N applications over the zero N rate every year. Split applications of N at seeding and stem elongation did not generally result in higher DM yields than the corresponding single applications of N at seeding. The crude protein concentration ranged from 5.1 to 12.1% in the zero N check plot and from 7.1 to 14.9% in the N-fertilized plots. The NO 3 -N concentration in tissue was generally less than 0.10%, although NO 3 -N concentrations up to 0.34% were recorded in oats at 200–300 kg N/ha rates. For barley and triticale, the mean in vitro digestibility of DM was 57.2 and 58.3%, respectively, while the mean in vitro digestibility of DM for oats was much lower at 46.9%. In vitro digestibility of DM was affected very little by rates of N. The limitations in using cereals for forage are discussed.