Seasonal distribution of pasture production in New Zealand

Abstract

Pasture growth rates for seven years are presented for a site on the Otago Plateau at an altitude of 1080 m on the western side of the Rock and Pillar Range in Central Otago. Yields obtained from grazed pasture established on cultivated ground were measured by a standardised cutting method using a moveable cage technique. The mean yield and standard deviation over all years of measurement are given for standard dates at 14 day intervals. The growing season of about 170 days was from mid October to late March. Growth rates were highest in late spring and declined steadily over summer and early autumn; production was negligible during the winter months of June, July, and August. Forty-seven per cent, 43%, and 9% of the annual yield occurred in spring, summer, and autumn respectively. The mean annual yield was 2540 kgha⁻¹ dry matter. The ‘Grasslands Ruanui’ ryegrass component of the sown sward was reduced by winter climatic conditions and made only a minor contribution from the fourth year after sowing; it is therefore considered to be an unsuitable cultivar at this altitude. By the sixth year Grasslands ‘Ruanui’ cocksfoot and clovers were contributing about 40% and 50% of the total yield respectively. Although annual rainfall was low (541 mm) in the area, there was only a slight soil moisture deficit; low temperature was the main factor restricting pasture growth. General climatological, rainfall, and temperature data for the site are also presented.

Keywords:

• Pasture production
• tussock grassland
• climate
• seasonal distribution