Global patterns and drivers of soil total phosphorus concentration

Xianjin He,Yuanyuan Huang,Yongchuan Yang,Julian Helfenstein,Laurent Augusto,Daniel S Goll,Bruno Ringeval,Zhiqiang Wang,Enqing Hou,Kailiang Yu,Yingping Wang

doi:10.5194/essd-13-5831-2021

Abstract

Abstract. Soil represents the largest phosphorus (P) stock in terrestrial ecosystems. Determining the amount of soil P is a critical first step in identifying sites where ecosystem functioning is potentially limited by soil P availability. However, global patterns and predictors of soil total P concentration remain poorly understood. To address this knowledge gap, we constructed a database of total P concentration of 5275 globally distributed (semi-)natural soils from 761 published studies. We quantified the relative importance of 13 soil-forming variables in predicting soil total P concentration and then made further predictions at the global scale using a random forest approach. Soil total P concentration varied significantly among parent material types, soil orders, biomes, and continents and ranged widely from 1.4 to 9630.0 (median 430.0 and mean 570.0) mg kg−1 across the globe. About two-thirds (65 %) of the global variation was accounted for by the 13 variables that we selected, among which soil organic carbon concentration, parent material, mean annual temperature, and soil sand content were the most important ones. While predicted soil total P concentrations increased significantly with latitude, they varied largely among regions with similar latitudes due to regional differences in parent material, topography, and/or climate conditions. Soil P stocks (excluding Antarctica) were estimated to be 26.8 ± 3.1 (mean ± standard deviation) Pg and 62.2 ± 8.9 Pg (1 Pg = 1 × 1015 g) in the topsoil (0–30 cm) and subsoil (30–100 cm), respectively. Our global map of soil total P concentration as well as the underlying drivers of soil total P concentration can be used to constraint Earth system models that represent the P cycle and to inform quantification of global soil P availability. Raw datasets and global maps generated in this study are available at https://doi.org/10.6084/m9.figshare.14583375 (He et al., 2021).

Highlights

In terrestrial ecosystems, to a depth of 1 m from the land surface, most of the P is found in the soil (Zhang et al, 2021)
Consistent with a recent global synthesis that focused on soil P fractions (Hou et al, 2018a), our result indicated that mean annual temperature (MAT) was a more important predictor of soil total P concentration than MAP
By constructing a database of total P concentration globally, we quantified the relative importance of multiple soilforming variables for predicting soil total P concentration and further estimated it at the global scale

Summary

Introduction

To a depth of 1 m from the land surface, most of the P is found in the soil (Zhang et al, 2021). Few studies have quantified the relative importance of these variables for predicting soil total P concentration at a global scale (Delgado-Baquerizo et al, 2020; Augusto et al, 2017; Yang et al, 2013) Such an understanding can guide the management of the soil P supply in agroecosystems of different regions (Ringeval et al, 2017) and is crucial for both mapping soil total P concentration in natural terrestrial ecosystems (Reed et al, 2015) and simulating ecosystem functioning (Achat et al, 2016a)

Methods

Results

Discussion

Conclusion