Acidification of soils on a transect from plains to slopes, south western New-South-Wales

Abstract

Samples were collected from unimproved road reserves and adjacent paddocks on a 90 km transect crossing red-brown earth soils in the west and red earth soils in the east. Measurements of pH in water and CaCl2 indicated that the red earths have been acidified by approximately 0.5 pH units over the last 30-40 years. Small increases in CaCl2-extractable A1 were also recorded for the acidified red earths. The red-brown earths do not appear to have been markedly affected by soil acidification to date. Clay mineralogical data and measurements of cation exchange capacity of the <2 µm fraction indicate that red-brown earths are better buffered against acidification than red earths. However, small differences in management practices and rainfall along the transect may also be partially responsible for differences in acidification between soil types.