Global Distribution and Influencing Factors of Plant‐Available Phosphorus in (Semi‐)Natural Soils

Abstract Phosphorus (P) is frequently a limiting nutrient for plant growth in natural ecosystems. Determining plant‐available P concentration in soil is essential for pinpointing areas where P availability might restrict plant growth and terrestrial carbon sequestration. However, the worldwide distribution and factors influencing plant‐available P in (semi‐)natural soils are not well understood. Here, we have developed a comprehensive global database that compiles plant‐available P measurements using five prevalent analytical methods: Olsen, Bray‐1, Mehlich III, Colwell, and AB‐DTPA. The data set encompasses 6,253 plant‐available P measurements in (semi‐)natural soils (under natural ecosystems and >10 years since anthropogenic activities) at 3,353 globally distributed sites. Leveraging this extensive database, we initially examined the global distribution and influencing factors of plant‐available soil P. Subsequently, we utilized a random forest model to delineate a detailed global map of plant‐available soil P patterns. Globally, plant‐available P varied over four orders of magnitude, from 0.01 to 99.2 mg kg −1 . The variation was best explained by parent material types and total soil P concentration. Random forest predicted plant‐available P increased significantly with latitude in both hemispheres, though with large longitudinal variations. Global stock of plant‐available P was estimated to be 0.73 Pg and 1.59 Pg at 0–30 cm and 30–100 cm soil depths. Our analysis provides insight into the underlying drivers of plant‐available P in (semi‐)natural soils, presents a spatially explicit assessment of plant‐available soil P, which can provide a basis for assessing, predicting, and understanding global patterns of terrestrial P limitation and the functioning of the Earth system.