Seasonal distribution of pasture production in new zealand xviii. South Taranaki

Abstract

Pasture growth rates for 8 years are presented for a site on the Waimate plains of South Taranaki. Yields obtained from grazed permanent pasture were measured with a standardised cutting method using a moveable cage technique. Two cutting intervals were used and the mean yield and standard deviation over all years of measurement are given for standard dates at 14 and 28 day intervals. Growth rates under 28 day cutting intervals were highest in late spring and rapidly declined over summer. Autumn growth rates were reasonably constant, then declined through winter to the lowest growth rates in mid July. Fourteen day growth rates displayed a different pattern — peaking earlier in spring but at lower values — which remained reasonably constant well into summer. Autumn growth rates rose above those from late summer, and then declined in the winter months to similar values as under 28 day cutting. Forty-six per cent and 36% of annual yield occurred in the spring months for 28 and 14 day cutting intervals respectively, while corresponding figures for summer were 26 and 29%, and autumn 18 and 23%. The winter months produced only 11 and 12% of the mean annual yields of 13 150 kg DM/ha and 10 670 kg DM/ha for 28 day and 14 day cutting intervals respectively. The greatest variation in growth rates between years occurred over the summer and early autumn. Soil moisture and rainfall data indicated that variable summer rainfall caused soil moisture levels to become the critical factor affecting growth rates. Under both cutting regimes the ryegrass component reached highest growth rates in spring, and white clover growth was highest in summer. Climatological data, mean 14 day rainfall, and air temperature during the period of pasture measurement are given. © 1984 Taylor and Francis Group, LLC. All Rights Reserved.