EFFECTS OF NITROGEN ON HERBAGE YIELDS OF REED CANARYGRASS HARVESTED AT VARIOUS DEVELOPMENTAL STAGES

Abstract

A pure stand of reed canarygrass (Phalaris arundinacea L.) was fertilized at rates of 0, 56, 112 and 224 kg/ha of elemental nitrogen (N) 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.Highly significant year effects were attributed to yearly variations in rainfall. Significant yield increases were recorded for each successively higher N rate in all years, as measured by both first-cut and total yields of DM, DDM and CP. First-cut DM yields increased to the seed-set stage, whereas DDM and CP yields declined significantly at that stage, having reached a maximum at the heading stage. Total DM yields declined slightly after the heading stage, while DDM and CP yields declined significantly after that stage. While first-cut yield responses to N rates were somewhat greater at the later stages, total yield responses were greater at the boot and heading stages as a result of greater aftermath production.