Lime increases productivity and the capacity of lucerne (Medicago sativa L.) and phalaris (Phalaris aquatica L.) to utilise stored soil water on an acidic soil in south-eastern Australia

Abstract

We hypothesised that a) species with greater acid soil tolerance have an increased capacity to utilise incipient rainfall; and b) liming increases the productivity and the ability of pasture species to utilise available water resources in the profile of an acid soil. A field experiment was established on a moderately acidic yellow Kandosol and monitored over 5 years. Five perennial pasture species including lucerne (Medicago sativa L.), phalaris (Phalaris aquatica L.), chicory (Cichorium intybus L.), tall fescue (Festuca arundinacea Schreb.) and cocksfoot (Dactylis glomerata L.), were sown in monocultures with and without 2.9 t/ha lime. Both lucerne and phalaris were more persistent than chicory, tall fescue and cocksfoot under severe drought, despite both being considered sensitive to soil acidity. Surface liming increased the soil water deficit by up to 27 mm at 0.75–1.65 m under perennial pastures compared to unlimed treatments, despite lime having no physical presence at that depth. Lime increased lucerne, phalaris and cocksfoot cumulative herbage biomass by 150, 30 and 20 %, respectively, but had no significant effect on chicory or tall fescue biomass. The two most acid-sensitive species, lucerne and phalaris, were more resilient under drought despite the acidic nature of the soil. We contend that species sensitive to acidity can be a valuable addition to pastures on acid soils. Lime used in conjunction with deep-rooted perennial species is likely to maximise the ability of pastures to utilise scarce available soil water reserves.