Long-term atmospheric carbon dioxide enrichment decreases soil phosphorus availability in a grazed temperate pasture

•Elevated CO2 negatively affected soil P availability in a grazed temperate pasture.•Long-term CO2 enrichment decreased labile P while increased organic P forms.•Organic P accumulation was related to microbial activity and higher root biomass and turnover.•Adsorption on reactive mineral surfaces could have increased organic P accumulation.