Long-term liming ameliorates subsoil acidity in high rainfall zone in south-eastern Australia

Management of Acid Soils Through Efficient Rotations (MASTER), is a long-term agronomic experiment commenced in 1992. The primary objective was to develop and demonstrate a sustainable farming system that is agriculturally productive, economically viable and environmentally effective to manage the highly acid soils in the high rainfall region (550'800 mm) of south-eastern Australia. The experiment was a fully phased design with 3 major treatment contrasts, a) annual systems versus perennial systems; b) limed versus unlimed treatments; and c) permanent pastures versus pasture-crop rotations. Results showed that the soil acidification rate was 0.1 pH units per year under the production system studied, and acidity amelioration rate was 0.044 pH units per year under the liming regime used. It is estimated that the system requires 270- 300 kg lime/ha/year, or 1.6-1.8 t lime/ha every 6 years, to keep the system sustainable. It was concluded that the subsoil acidity can be alleviated by surface liming over the long term.