Carbon footprint of synthetic nitrogen under staple crops: A first cradle-to-grave analysis

More than half of the world’s population is nourished by crops fertilized with synthetic nitrogen (N). However, N fertilization is a major source of anthropogenic emissions, augmenting the carbon footprint (CF). To date, no global quantification of the CF induced by N fertilization of the main grain crops has been performed, and quantifications at the national scale have neglected the CO2 assimilated by plants. A first Cradle-Grave life cycle assessment was performed to quantify the CF of the N fertilizers’ production, transportation, and application to the field and the uses of the produced biomass in livestock feed, human food, and biofuel production. We quantified direct and indirect inventories emitted or sequestered by the N fertilization of grain crops (wheat, maize, and rice). Grain food produced with N fertilization had a net CF of 7.4 Gt CO2eq. in 2019 after excluding the assimilated C in plant biomass, which accounted for a quarter of the total CF. The Cradle (fertilizer produ..., , , # Carbon footprint of synthetic nitrogen under staple crops: A first cradle-to-grave analysis [https://doi.org/10.5061/dryad.8sf7m0cxg](https://doi.org/10.5061/dryad.8sf7m0cxg) | Sheet | Contents | | :---- | :-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | | S1 | Data about yield production, harvested area, total N consumption, N application rate, N agronomic efficiency and N consumption from each fertilizer type and for each crop | | S2 | Emission and sequestration of gases during fertilizer production for each region ...