Birdsfoot trefoil (Lotus corniculatus) and greater lotus (Lotus uliginosus) in perennial pastures in eastern Australia. 1. Effects of grazing management on persistence

摘要

A study was undertaken in the Perennial Pasture Zone in New South Wales, Australia, to investigate the potential of lotus-based pastures (greater lotus, Lotus uliginosus Schukr.; birdsfoot trefoil, Lotus corniculatus L.) to improve grazing production. The study was based on a methodology that combined a grazing experiment to determine the effects of grazing management on lotus persistence, with a co-learning phase to assess the adaptation and applications of lotus across the high rainfall zone. The present paper reports on the grazing experiment that was replicated in 4 regions (North Coast, South Coast, Northern Tablelands, Southern Tablelands) and that included combinations of grazing strategy (summer rest, autumn rest, 14-day spell or 28-day spell), grazing intensity (low or high herbage mass), Lotus species and cultivar (L. uliginosus cvv. Grasslands Maku, Sharnae; L. corniculatus cv. Grasslands Goldie or ‘Spanish’ breeding line) and companion grass (sown or volunteer) treatments. The experiment provided results for the establishment and botanical presence of both Lotus species, and the expression of their persistence mechanisms in these 4 environments. Greater lotus cv. Grasslands Maku established best under coastal conditions and birdsfoot trefoil cv. Grasslands Goldie established best under tablelands conditions. The degree of nodulation of greater lotus cv. Sharnae and birdsfoot trefoil cv. Grasslands Goldie was less than nodulation of greater lotus cv. Grasslands Maku, but nodulation had no apparent effect on seedling vigour. The population density of all Lotus cultivars declined substantially at the North Coast, South Coast and Southern Tablelands sites during severe drought conditions. However, both birdsfoot trefoil cv. Grasslands Goldie and greater lotus cv. Grasslands Maku remained relatively stable at the Northern Tablelands site with greater lotus cv. Grasslands Maku maintaining 20–40% presence and birdsfoot trefoil cv. Grasslands Goldie retaining 30–50% presence, depending on time of year. In general, there was little effect of grazing management practice on arresting the decline in lotus presence due to drought, or on enhancing the regeneration processes associated with lotus persistence.