CSIRO PUBLISHING www.publish.csiro.au/journals/ajar Australian Journal of Agricultural Research, 2006, 57, 1045–1055 Pasture and sheep responses to lime application in a grazing experiment in a high-rainfall area, south-eastern Australia. I. Pasture production G. D. Li A,F , K. R. Helyar A , S. J. Welham B , M. K. Conyers A , L. J. C. Castleman C , R. P. Fisher A , C. M. Evans D , B. R. Cullis A , andP. D. Cregan E A E H Graham Centre for Agricultural Innovation, NSW Department of Primary Industries, Wagga Wagga Agricultural Institute, Wagga Wagga, NSW 2650, Australia. B Rothamsted Research, Harpenden AL5 2JQ, United Kingdom. C NSW Department of Primary Industries, Lockhart, NSW 2656, Australia. D Central West Farming System, Condobolin, NSW 2877, Australia. E E H Graham Centre for Agricultural Innovation, School of Agriculture, Charles Sturt University, Wagga Wagga, NSW 2678, Australia. F Corresponding author. Email: guangdi.li@dpi.nsw.gov.au Abstract. ‘Managing Acid Soils Through Efficient Rotations (MASTER)’ is a long-term pasture–crop rotation experiment commenced in 1992. One of the objectives was to demonstrate the extent of crop, pasture, and animal responses to lime on a typical acidic soil in the 500–800mm rainfall zone in south-eastern Australia. Two types of pastures (perennial v. annual pastures) with or without lime application were established in 1992. This paper presents the results of the pasture dry matter (DM) responses to lime application over 6 years from 1992 to 1997. Results showed that both perennial and annual pastures responded positively to lime on a highly acidic soil on the south-west slopes of New South Wales. Averaged across pasture types and 5 growing seasons, the limed pastures produced 18% more pasture DM (520 kg/ha, P < 0.05) than the unlimed pastures. Significant responses to lime were detected on perennial pastures (610 kg DM/ha, P < 0.05), but not on annual pastures, although the limed annual pastures produced more DM (420 kg/ha, P = 0.20) than the unlimed annual pastures. There was a large seasonal variation in pasture growth rate with the significant lime responses in winter and spring on both perennial pastures (P < 0.05) and annual pastures (P < 0.10 in winter and P < 0.05 in spring), but no responses in autumn and summer on either perennial or annual pastures. The extra growth in winter is of importance as winter is the period when feed is normally inadequate and limits stocking rates. It is recommended that perennial-based pastures should be promoted for the purposes of productivity, in terms of increasing pasture production and improving feed quality, and for the environmental benefits in terms of alleviating the soil acidity problem and reducing the risk of dryland salinity in the high-rainfall zone in south-eastern Australia. Additional keywords: acidification, acid soils, lime response, annual pasture, perennial pasture. Introduction Soil acidification is one of the most important land degradation issues in the 500–800 mm rainfall zone of south- eastern Australia, although it is not as easily recognised as other land degradation problems such as salinity and erosion (Scott et al. 2000). It has been documented that current farming practices have been accelerating the acidification process (Williams and Donald 1957; Williams 1980; Helyar and Porter 1989), resulting in long-term degradation of the soil. As this degradation has not been visible at the soil surface, the farming community has relied on the agricultural scientists to identify the problem and now offer management solutions. Lime application has proved to be one of the most effective ways to alleviate the acidity problem in mixed farming systems where cropping enterprises can be used to pay for high initial rates of lime over a short period (Scott et al. 1997; Li et al. 2001a). However, it is always more difficult to demonstrate economically viable responses to lime in pasture and animal production than in cropping systems (Scott et al. 2000). Factors contributing to this difficulty are often the low profitability per hectare of grazing enterprises, subsurface acidity (Al toxicity), the use of species with relative acid tolerance in the grazing system, and the high initial cost of lime (a capital input to raise the soil pH to a suitable status). Pasture yield responses to lime have been variable and inconsistent in Australia. In southern New South Wales, © CSIRO 2006 10.1071/AR05298 0004-9409/06/101045