WINTER HULLESS BARLEY RESPONSE TO NITROGEN RATE AND TIMING AND FOLIAR PHOSPHORUS

Abstract

Hulless barley (Hordeum vulgare L.) is higher in energy density and protein than hulled barley but management recommendations for this new crop are lacking. Intensively managed hulled barley receives two spring nitrogen (N) applications. How this will affect winter hulless barley yield and protein is unknown. ‘Doyce’ hulless barley was planted following corn (Zea mays L.) at seven site-years in the Coastal Plain of Virginia from 2005 to 2007. Spring N was applied as urea ammonium nitrate (UAN, 30% N) in an incomplete factorial of treatments at Zadoks growth stage (GS) 25 and 30 broadcast at rates of 0, 45, 67, and 89 kg N ha−1. Six kg ha−1 of phosphorus (P) was foliar applied at GS 30 to treatments receiving 45:45 (45 kg N ha−1 at GS 25 and 45 kg N ha−1 at GS 30) and 45:67 N splits. Additionally, 34 kg N ha−1 as UAN was applied at GS 45 to treatments previously receiving either 45:45 or 45:67. Grain test weight increased with increasing N rate verifying that high spring N rates can be applied without negatively impacting grain test weight in this environment. Grain protein responded positively to increasing N rates as additional N at GS 45 increased protein by 0.7%. To maximize yields, 112 kg N ha−1 applied as 45 kg N ha−1 at GS 25 and 67 kg N ha−1 at GS 30 was necessary. Supplying the majority of spring N need at GS 30 proved important to matching barley N demand and achieving high yields.