RESPONSE OF ORCHARD GRASS TO MULTIPLE HARVESTS AND RATES OF NITROGEN IN POST-SEEDING YEARS
Frode orchard grass (Dactylis glomerata L.) was fertilized with 99–495 kg N/ha/yr in three equal applications and harvested three or four times per season over a 3-yr period to determine the productivity, quality of forage and persistence of stands. The application of N resulted in significant (P =.001) linear and quadratic increases in dry matter (DM) yields. Higher DM yields were obtained with the 3-harvest system while the yield distribution within the season was more uniform for the 4-harvest system. Total N concentrations of orchard grass increased linearly with the N rates. Total N yields were dependent on the rates of applied N with the recovery of applied N ranging from 39 to 70% at 99–297 kg N/ha/yr, respectively. The in vitro disappearance of DM was slightly reduced by the high N rates in the 1st and 2nd harvests. The nitrate-N concentrations were highest in the early and late summer ranging from.11 to.29% at 297–495 kg N/ha/yr, respectively. The persistence of orchard grass was better under the 4- than the 3- harvest system.