Figures from Department of Soil and Environment, Swedish University of Agricultural Science
https://www.slu.se/miljoanalys/statistik-och-miljodata/miljodata/webbtjanster-miljoanalys/markinfo/markinfo/markkemi/utbytbart-aluminium-och-total-aciditet/

Replaceable aluminum and total acidity (1993-2002)

Exchangeable aluminum (mmolc / kg dry matter, extractant: 1 M KCl) and total acidity (extraction agent: 1N NH4OAc solution, buffered to pH 7.0)
Exchangeable aluminum in the O-horizon Total acidity in the O-horizon
Exchangeable aluminum in the B-horizon Total acidity in the B-horizon
Exchangeable aluminum in the C-horizon Total acidity in the C-horizon