Long-term trajectories of the C footprint of N fertilization in Mediterranean agriculture (Spain, 1860–2018) Aguilera, Eduardo Infante Amate, Juan Greenhouse gas emissions Nitrous oxide Environmental History Mediterranean climate Nitrogen The authors are grateful to the Spanish Ministry of Economy and Competitiveness (AgroSceNA-UP, PID2019-107972RB-I00), the Instituto Nacional de Investigacion y Tecnologia Agraria y Alimentaria of Spain (MACSUR02-APCIN2016-0005-00-00) and the Comunidad de Madrid, Spain (AGRISOST-CM S2018/BAA-4330). E Aguilera is supported by a Juan de la Cierva research contract from the Spanish Ministry of Economy and Competitiveness (IJC2019-040699-I and FJCI-2017-34077). L Lassaletta is supported by Spanish Ministry of Economy and Competitiveness (MINECO) and European Commission ERDF Ramon y Cajal Grant (RYC-2016-20269), Programa Propio from UPM, and acknowledges the Comunidad de Madrid (Spain) and structural funds 2014-2020 (ERDF and ESF). A Sanz-Cobena gratefully acknowledges the Autonomous Community of Madrid and UPM for their economic support through the research project APOYOJOVENESNFW8ZQ-42-XE8B5K. All authors are grateful to this project for covering the publication fees. The authors are very grateful to the Spanish Ministry of Agriculture for gathering and providing detailed information with respect to crop production and management. The authors gratefully acknowledge the two anonymous reviewers for their constructive and useful suggestions. Synthetic nitrogen (N) fertilization has helped boost agricultural yields, but it is also responsible for direct and indirect greenhouse gas (GHG) emissions. Fertilizer-related emissions are also promoted by irrigation and manure application, which has increased with livestock industrialization. Spanish agriculture provides a paradigmatic example of high industrialization under two different climates (temperate and Mediterranean) and two contrasting water management regimes (rainfed and irrigated). In this study, we estimated the historical evolution of the C footprint of N fertilization (including all the life cycle GHG emissions related to N fertilization) in Spanish agriculture from 1860 to 2018 at the province level (50 provinces) for 122 crops, using climate-specific N2O emission factors (EFs) adjusted to the type of water management and the N source (synthetic fertilizer, animal manure, crop residues and soil N mineralization) and considering changes in the industrial efficiency of N fertilizer production. Overall, N-related GHG emissions increased ∼12-fold, up to 10–14 Tg CO2e yr−1 in the 2010s, with much higher growth in Mediterranean than in temperate areas. Direct N2O EFs of N fertilizers doubled due to the expansion of irrigation, synthetic fertilizers and liquid manure, associated with livestock industrialization. Synthetic N production dominated the emissions balance (55%–60% of GHGe in the 21st century). Large energy efficiency gains of industrial fertilizer production were largely offset by the changes in the fertilizer mix. Downstream N2O emissions associated with NH3 volatilization and NO3 − leaching increased tenfold. The yield-scaled carbon footprint of N use in Spanish agriculture increased fourfold, from 4 and 5 Mg CO2e Mg N−1 to 16–18 Mg CO2e Mg N−1. Therefore, the results reported herein indicate that increased productivity could not offset the growth in manufacture and soil emissions related to N use, suggesting that mitigation efforts should not only aim to increase N use efficiency but also consider water management, fertilizer type and fertilizer manufacture as key drivers of emissions. 2021-09-28T10:48:27Z 2021-09-28T10:48:27Z 2021-08-05 info:eu-repo/semantics/article Eduardo Aguilera et al 2021 Environ. Res. Lett. 16 085010. [https://doi.org/10.1088/1748-9326/ac17b7] http://hdl.handle.net/10481/70492 10.1088/1748-9326/ac17b7 eng http://creativecommons.org/licenses/by/3.0/es/ info:eu-repo/semantics/openAccess Atribución 3.0 España Institute of Physics Publishing