This data set provides a time series of calcium, magnesium, and potassium concentrations extracted from soil samples from a laboratory column extraction study conducted in 2002. Soils used in the columns were originally collected in 1998 in Fazenda Vitoria, a cattle ranch 6 km north of the town of Paragominas, Para, Brazil. The soils were from contrasting land uses of primary forest (mata), secondary forest (capoeira), or pasture (pasto). Water equilibrated with increasing concentrations of CO2 was used to extract cations from the soil columns. Data represent the time series of cation concentrations in the extract solutions as well as the total content of cations removed from the soils. There is one comma-delimited ASCII file with this data set.