COMPARISON OF EARLY, NORMAL AND LATE SOWING AT 3 RATES OF NITROGEN ON THE YIELD, GRAIN NITROGEN AND SCREENINGS CONTENT OF BLENHEIM SPRING MALTING BARLEY IN IRELAND

Nine experiments were carried out on three different soil types in the south-east of Ireland over three years (1989, 1992 and 1993) to test the effect of early, normal and late sowing at three rates of fertilizer nitrogen (100, 125, 150 kg/ha) on the yield and grain quality ex-farm of spring malting barley (cv. Blenheim). Early sowing (January or February) was not possible in 1990 and 1991 due to wet weather. Sowing date had a pronounced effect on grain yield and grain N content in all three years. In 1989 and 1992, the earliest-sown barley (January or February) gave significantly greater yields than later-sown crops (March and April) in five of the six experiments. The earliest-sown barley gave the lowest grain N in all six experiments and there was a gradual and significant increase in grain N content as sowing date was delayed. In 1993 the earliest-sown barley (February) gave significantly lower yield and greater grain N than the March-sown crop in all three experiments. The lower yield of the February-sown barley in 1993 was due to the significantly reduced number of grains/ear. The April-sown barley gave significantly lower yield and greater grain N than the earlier-sown crops in eight out of the nine experiments. In 1989 and 1992 only one of the six experiments, Ferns 1992, gave a significant yield response to increased rate of N (125 kg/ha). But in 1993, 125 kg N/ha significantly increased grain yield in all three experiments and 150 kg N/ha gave a further significant increase in yield in two of the experiments. Increasing increments of fertilizer N significantly increased grain N in all nine experiments.