THE VARIABILITY OF PH IN ACID SOILS OF THE SOUTHERN HIGHLANDS OF NEW-SOUTH-WALES

We have examined the spatial variation in pH (0.01M CaCl2) of acid soils of the Southern Highlands of New South Wales. Grid and random samplings were made at three and seven sites, respectively, over areas of 1 ha or less. The pH range at each site was 0.3 to 1.5 pH units, and 30% to 100% of this variation could occur within a square meter. The management history of the area contributed to the magnitude and spatial scale of pH variation. The composite sample pH corresponded closely with the arithmetic mean pH of the individual cores. The mode of the frequency distribution of pH often tended toward the acid side of the mean and composite sample pH. This may have influenced the utility of lime requirement determination based on the composite sample. The relative proportions of three plant species and bare patches in a mixed pasture are then shown to have been influenced by the variations in soil acidity within a field. © 1990 Williams & Wilkins.