Extended Data Fig. 2: Spatially explicit maps illustrating the soil-P budgets for various crop types in 1970 and 2017 across 44 nations exporting soil-P deficits (kg P/ha/yr).
From: Impacts of global trade on cropland soil-phosphorus depletion and food security
a1-9 and b1-9 refer to the year 1970 and 2017, respectively. c1-c9 are the changes between 1970 and 2017, where blue signals rising soil-P deficits, and red signals declining soil-P deficits or increasing soil-P surplus. Basemaps from Natural Earth (https://www.naturalearthdata.com/).