Plant nutrient-acquisition strategies promote primary phosphorus mineral weathering during early pedogenesis

Abstract

Phosphorus (P) is a critical macronutrient affecting ecosystem development. Unlike nitrogen, ecosystem P originates primarily from mineral-bound forms, particularly apatite, released during soil development. Although primary P minerals are sparingly soluble, they can be mobilised through diverse nutrient-acquisition strategies (NAS) of plants and their associated microorganisms. This review synthesises recent advances linking specialised root strategies, mycorrhizal associations, and nitrogen-acquisition mechanisms to primary P dissolution during early pedogenesis. We detail how specialised roots (e.g., cluster and dauciform roots) exude large quantities of carboxylates and protons to promote rapid mineral weathering, while mycorrhizal associations contribute through fungal secretion of carboxylates and the stimulation of P-solubilizing microorganisms in the hyphosphere. Furthermore, we elucidate a key biogeochemical coupling: nitrogen-acquisition strategies, specifically biological nitrogen fixation and ammonium uptake, intensify P mineral weathering both actively (carboxylates release to meet high metabolic P demands) and passively (proton excretion during charge balance maintenance). Evidence from chronosequences and controlled experiments demonstrated that specialised root and biological nitrogen fixation contributed more to P mineral weathering than mycorrhizal strategies and free-living microoragnism during carbon-limited early pedogenesis (< 100 years). We posit that conceptualizing NAS as integrated plant–microorganism systems are essential to resolving the dissolution mechanisms, particularly under the climate-driven expansion of young soils from glacier retreat and land erosion. Future research should prioritise identifying how specific root functional traits are matched with microbial partners to optimise C allocation and maximise mineral weathering, as well as elucidating key metabolic pathways to provide a mechanistic basis for ecosystem restoration and sustainable agriculture.