Fig. 2: Estimation of soil available phosphorus (P) levels in China.

a Theoretical model of agronomic and environmental assessment of soil available P levels. Agronomic and environmental soil P thresholds are delineated based on the soil available P concentration of the soil, either directly measured or inferred from another soil P availability index, as outlined by ref. 30. b Critical level of soil available P for production of different crops and for P leaching potential in the five P management zones in China. c Grid-scale soil available P levels for maize production. d Grid-scale soil available P levels for rice production. e Grid-scale soil available P levels for wheat production. Source data are provided as a Source Data file. Base map data adapted from GS(2020)4619, http://bzdt.ch.mnr.gov.cn/. Map created using ArcGIS software.