Growth periodicity of introduced pastures on the northern tablelands of New South Wales

Abstract

This paper reports on the growth periodicity of introduced temperate perennial pastures in a summer-rainfall environment in the high-rainfall zone of eastern Australia. Data were derived from an experiment (1985-87) directed at evaluating pasture cultivars when sown in binary mixtures grazed by sheep. The data were also simulated by using the decision support system SheepO (Version 4·0) and validated by visual techniques, deviance measures, and statistical tests. The model simulated pasture growth rate and total biomass with acceptable accuracy. The study provided a quantification of the growth rhythm of temperate perennial pastures in this environment. The data show that growth rhythm comprises a high growth rate (>50 kg DM/ha·day) during the primary growth cycle in spring, a moderate growth rate (20-50 kg DM/ha·day) during the secondary growth cycle in summer-autumn, and low growth rate (<20 kg DM/ha·day) in winter. The growth performance of introduced pastures based on cv. Demeter tall fescue (Festuca arundinacea) exceeded that of pastures based on cv. Sirosa phalaris (Pharlaris aquatica) in all seasons, at low and high stocking rates, and in all 3 years. The results highlight the potential for pasture cultivars with enhanced seasonal growth rate to increase the pasture feed supply for grazing animals.