Seasonal variation of pH, aluminium, and manganese in acid soils from north-eastern Victoria

Abstract

Seasonal variation in pH (measured in H2O or 0.01 mol CaCl2/L) and in Al and Mn extracted by 0.01 mol CaCl2/L are reported for north-eastern Victoria. Seasonal variation in pH(H2O) was significantly (P<0.05) greater than either the spatial variation or laboratory error. There was no significant (P<0.05) seasonal variation in pH(CaCl2). For pH (H2O), values were observed to increase after the autumn break, to peak at or near midwinter, and to decrease slowly over the spring and summer months to lowest values in late summer. Seasonal changes for pH(H2O) were significantly (P<0.05) related to the ionic strength of the 1 : 5 soil : water extract. Significant seasonal variations (P<0.05) occurred for extractable Al and Mn in a podsolised red earth and a red podsolic. Seasonal effects were a significant (P<0.05) source of variation for the methods used in this study and should, therefore, be considered in any comparative or predictive studies using these methods.