Soil acidification under pastures of north-eastern Victoria five years after liming

Abstract

The effects of liming and perennial species of clover on soil acidification were studied in Victoria, Australia. Five soil treatments were applied: lime at 0, 0.5, 1.5 and 5.5 t/ha, and sulfur at 128 kg/ha. Three pastures, sown in 1987, were evaluated: phalaris (Phalaris aquatica) sown with subterranean clover (Trifolium subterraneum); cocksfoot (Dactylis glomerata) sown with subterranean clover; and subterranean clover with volunteer annual grasses. pH and Al concentrations were determined at 0-10 and 10-20 cm soil depths in 1988 and 1992. Pasture treatment had no effect on the rate of pH decline. Soil treatment depth and time had significant effects on pH. With the 5.5 t/ha lime treatment, soil pH increased from 4.2 to 5.6 in 1988 in the 0-10 cm soil layer and then decreased to 4.7 in 1992. In the 10-20 cm layer, pH increased from 4.2 in 1988 to 4.6 in 1992. Lime applications (5.5 t/ha) significantly reduced Al concentrations where lime had previously been applied. Preliminary annual soil acidification rates were calculated as 2.47 and 5.95 kmol H+/ha following lime applications of 5.5 t/ha, using short and long pH buffering capacity figures, respectively.