Fig 1. Ordination diagram showing the results of PCA analysis with total concentration of Al in soil extracts in contaminated slightly acidic Litavka and alkaline Malín soils.

Treatment abbreviations: C—control, Ca—lime application, P—superphosphate application. Soil extractant abbreviations: KCl—exchangeable concentration of Al in soil (extracted by 0.5 mol/L KCl), CaCl₂—exchangeable concentration of Al in soil (extracted by 0.01 mol/L CaCl₂), H₂O —water-soluble concentration of Al in soil (extracted by deionised water), AA—exchangeable and carbonate concentration of Al in soil (extracted by 0.11 mol/L acetic acid), CA—exchangeable, carbonate, and reducible concentration of Al in soil (extracted by 0.11 mol/L citric acid), and OA—exchangeable, carbonate, and reducible concentration of Al in soil (extracted by 0.11 mol/L oxalic acid).