Long-term trajectories of the C footprint of N fertilization in Mediterranean agriculture (Spain, 1860–2018)

Abstract 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 promoted by irrigation manure application, which increased with livestock industrialization. Spanish agriculture provides a paradigmatic example of high industrialization under two different climates (temperate Mediterranean) contrasting water management regimes (rainfed irrigated). In this study, we estimated the historical evolution C footprint N (including all life cycle GHG related to fertilization) in from 1860 2018 at province level (50 provinces) 122 crops, using climate-specific 2 O emission factors (EFs) adjusted type source (synthetic fertilizer, animal manure, crop residues soil mineralization) considering changes industrial efficiency fertilizer production. Overall, N-related ∼12-fold, up 10–14 Tg CO e yr −1 2010s, much higher growth Mediterranean than temperate areas. Direct EFs fertilizers doubled due expansion irrigation, synthetic liquid associated production dominated balance (55%–60% GHGe 21st century). Large energy gains were largely offset mix. Downstream NH 3 volatilization NO − leaching tenfold. The yield-scaled carbon use fourfold, 4 5 Mg 16–18 . Therefore, results reported herein indicate that productivity could not manufacture use, suggesting mitigation efforts should only aim increase consider management, as key drivers