Fig. 5: Illustration of the approaches to estimate N output for different typologies under the GD-F scenario and graphical representation of specific N surplus reduction scenarios.
a, N output in 2030 under the same TMPs approach (that is, using average N input–output relationships from the baseline period 2015–2019). The input–output relationship is represented by a one-parameter hyperbolic function (blue line) fitted to the baseline period (2015–2019), with the blue triangle indicating the projected N output at the reduced N input level assumed under the GD-F scenario. b, N output in 2030 for the improved TMPs approach based on the full historical data from 1981–2019. For each typology, multiple one-parameter hyperbolic functions were fitted for eight 5-year periods between 1981 and 2019, shown as shaded blue lines. The improved TMP curve (green line) was derived by linearly extrapolating c to 2030 based on its evolution across eight historical intervals (equation (6)). The resulting N output in 2030 under this improved TMPs assumption is shown as green triangles. The dashed vertical line in both panels shows the reduced N input by 2030 under the GD-F scenario, that is, 20% less N input from fertilizer compared with the base year (2015–2019). c, Graphical representation of specific N surplus reduction scenarios. The base map shows the European domain and is used for illustrative purposes; it is based on N surplus data from ref. 18. Credit: icons in c, Canva.
