Phalaris and lime: improving productivity on an acidic soil in a drought-prone 'high-rainfall' environment

The experiment was conducted on a highly acidic Sodosol soil with hydrophobic properties on the Southern Tablelands, New South Wales. Prior to sowing, lime (CaCO3) was incorporated at 3.5 t/ha, increasing soil pHCa from 4.1 to 5.5 in the surface 0.10 m. Seven perennial pasture species, phalaris, cocksfoot, chicory, tall fescue, birdsfoot trefoil, grazing brome and Yorkshire fog were sown in monocultures. Available soil water (ASW) was monitored for 18 months following sowing, as were plant establishment, persistence and herbage mass. Lime increased ASW by up to 15% in the surface 0.30 m which was most likely due to increased infiltration. Total pasture herbage mass increased by an average of 33% due to lime in the establishment year whereas yield of sown perennial species increased by 60% on the limed treatments compared with the unlimed treatments. Lime had no effect on the establishment of any perennial species. Phalaris was the only species to persist beyond the first summer in the absence of lime with a basal frequency > 20% and most other species died in the second year, including cocksfoot which is commonly reported to be more acid tolerant. Lime increased phalaris yield by 69% in the second year. The two key findings from this study were that i) phalaris was the most viable perennial option for this highly acidic soil, despite previous reports of its relative sensitivity to acid soils, and ii) the increases in pasture yield due to lime were likely, in part, due to the observed increase in ASW.