The genesis of three podzol-like soils occurring over a climatic gradiant on Vancouver Island

Three soils occurring on a climosequence were studied to clarify certain aspects of Podzol genesis and Podzol classification. Data on physical, chemical, and soil solution characteristics of the three soils were collected and analysed. All measures of iron and aluminum were analysed and presented as mass per horizon. Rates of movement for calcium, magnesium, sodium, potassium, iron and aluminum between the canopy, forest floor, B₁ and B₂ horizons were also measured. The interpretations of different measures of iron and aluminum as an index of Podzol expression were shown to be inconsistent. A simple linear model was developed and applied to data from the three soils. The model defined the balance of additions, losses, transformations, and translocations within and between horizons for each site. The model results supported the following hypotheses: 1) The balance of additions, losses, translocations, and transformations vary across the climosequence. 2) The three soils studied can be identified by the balance of processes acting to produce sesquioxide rich B horizons. 3) Current Podzol classification criteria do not reflect differences in the balance of these processes. The model did not support the hypothesis that rates of biochemical cycling would be reflected in Podzol B horizon expression. Two distinct balances of processes forming iron and aluminum rich B horizons were shown to occur. In one site iron and aluminum accumulate primarily as a result of preferential loss of other soil constituents; in the other sites iron and aluminum are dominantly the product of eluviation from the Ae horizon and deposition in the B horizons. Current classification criteria grouped the two soils showing the most strongly contrasting genetic processes together as Brunisols while the intermediate balance was classified as a Podzol. The reasons for this inconsistency are discussed.Land and Food Systems, Faculty ofGraduat