NITROGEN AND ITALIAN RYEGRASS

Abstract

ABSTRACT In an experiment, described earlier (19) to study the regrowth of Italian ryegrass following a cut in late April, the N and nitrate‐N content of herbage at 3 levels of applied N followed a similar pattern to that noted in earlier years in Cambridge. N content, however, did not fall to such a low level as in Cambridge. N yield fell later and less quickly than in Cambridge. The application of a very high level of N, 175 lb/ac (196 kg/ha), raised N and nitrate‐N content and yield from the second or third week onwards. Changes with time in P and K content and yield were broadly similar to those for N. Level of N had only a small effect on content of P and K. Following the period of increase in yield of N, P and K, there was a period of about 6 weeks of relatively constant yield, followed by a fall. The content of N, P and K in fresh, rather than dry, herbage changed little with time from the fourth to the fourteenth week, despite major changes in crop maturity. The ratio P: K was little affected by level of N or time of harvest.