Driver Data source Methodology
Socio-economic drivers Socio-economic drivers Socio-economic drivers
Economic development World Bank (2018) GDP per capita, gross domestic product / midyear population
Consumption per capita for certain crop types FAOSTAT (2018), Zhang et al. (2015a) Production + import - export
Fertilizer to crop price ratio FAOSTAT (2018) Fertilizer price (Single Superphosphate) / crop price (maize)
Per hectare spending on agricultural machinery FAOSTAT (2018) Agricultural machinery, tractors per 100 sq. km of arable land
Patent application per capita World Bank (2018) Resident patent applications per capita
Education expenditure as a percentage of government spending World Bank (2018) Government expenditure on education
Agriculture, value added World Bank (2018) The net output of a sector after adding up all outputs and subtracting intermediate inputs
Ratio of net import of certain crop types FAOSTAT (2018), Zhang et al. (2015a) Net import / local production
Agronomic drivers Agronomic drivers Agronomic drivers
Crop mix FAOSTAT (2018), Zhang et al. (2015a) Percentage of the harvested area of a certain crop type, i.e., harvested area of a specific crop type / total harvested area
NUE Zhang et al. (2015a) N output (N in harvested crops) / N inputs
Adjusted average farm size Graeub et al. (2016) Residual of the regression of average farm size on arable land per capita, see Text S9 and Wu et al. (2018)
Conservation area ratio FAO AQUASTAT database Conservation agriculture area as % of arable land area = 100*Conservation agriculture area / Arable land area
P yield FAOSTAT (2018), Zhang et al. (2015a) P in harvested crops / harvested area
Accumulated P surplus Calculation P inputs (fertilizer and manure) - P output (P in harvested crops), accumulated since 1961
Accumulated P residual Calculation P surplus - P loss, accumulated since 1961