EFFECTS OF NITROGEN ON HERBAGE YIELDS OF TIMOTHY HARVESTED AT VARIOUS DEVELOPMENTAL STAGES

Abstract

A pure stand of local commercial timothy (Phleum pratense L.) was fertilized with N at rates of 0, 56, 112 and 224 kg/ha and harvested at the vegetative, shot-blade, boot, heading, anthesis and seed-set stages for three consecutive years. Yields of dry matter (DM), digestible dry matter (DDM) and crude protein (CP) were measured.Differences in precipitation resulted in highly significant year effects. Each increase in N rate gave a significant yield increase in all years and for both first-cut and total yield of DM, DDM and CP. First-cut yield of DM increased significantly to the anthesis stage, DDM yield increased to the boot stage and CP yield increased to the shot-blade stage. Total yield of DM was maximum at the anthesis stage, DDM total yield was statistically equal at all stages, and CP total yield declined significantly after the heading stage.