Geochemical inheritance from bedrock insoluble residues controls mineral nutrients enrichment and depletion in karst soils

Abstract This study investigates the geochemical mechanisms governing mineral nutrients (MNs) enrichment and depletion in stable, non-degraded summit/platform karst soils of Southwest China, to provide a theoretical basis for rocky desertification management, specifically addressing why specific trace elements accumulate despite the inherent nutrient deficiency of carbonate rocks. Using a stepwise tracing approach combined with dynamic bedrock leaching experiments on 20 profiles from these settings in Southwest China, we quantified the migration and transformation of major elements (Ca, Mg, K, Na, Fe, P) and trace elements (Ni, Cu, Mo) from parent material to evolved soil. Results indicate that, relative to background values, the studied karst soils exhibit depletion of Ca, Na, and P alongside enrichment of Fe, Ni, Cu, and Mo. We propose a “Stepwise Inheritance Model” wherein soil MNs are primarily inherited from the bottom soil (T 1 ), effectively retaining the geochemical signature of bedrock insoluble residues (Yt). Notably, while Cu and Mo are strongly influenced by Yt composition through single-source inheritance, Ni exhibits a likely dual-source mechanism governed by both residue inheritance and carbonate fraction leaching. These findings suggest that soil nutrient potential is geochemically inherited from the “pre-weathering history” of Yt in these settings. This implies that ecological restoration strategies in similar karst rocky desertification settings should integrate bedrock geochemical evaluation rather than relying solely on physical soil thickness metrics. These conclusions should not be extrapolated to other karst landforms without further validation.