The influence of cutting frequency and nitrogen fertilizer on the growth of kikuyu grass

Abstract

The influence of cutting frequency (3, 6 and 9 weeks) and high nitrogen rates (0, 950 and 2860 kg N ha-1 yr-1) on the growth of an established kikuyu grass (Pennisetum clandestinum) sward were studied over three years, in an irrigated field experiment at Taree (lat. 32¦s) on the mid-north coast of New South Wales. Forage yield was increased largely by nitrogen and to a lesser extent by increasing the harvest interval. Significant (P < 0.05) yield increases were obtained between 0 N and 950 N but not between 950 N and 2860 N. Yields ranged from 8900 kg DM ha-1 yr-1 (3 weeks, 0 N) to 25,200 kg DM ha-1 yr-1 (9 weeks, 2860). At 0 N, cutting every nine weeks increased yields over three and six weeks for most of the experimental period. There were no differences between three and six weeks at 0 N. With nitrogen there were significant yield differences between all cutting frequencies during periods of active growth. Longer cutting intervals increased the mean sward growth rates during most of the growing season but did not change the seasonal pattern of growth.Nitrogen yield increased with nitrogen rate and as cutting interval increased. Yields varied from 239 kg N ha-1 yr-1 (6 weeks, 0 N) to 932 kg N ha-1 yr-1 (9 weeks 2860 N). Nitrogen content was reduced as cutting interval increased.