Institutional nitrogen footprint: Quantification of the nitrogen footprint of a Spanish Research Center.

Reactive nitrogen (N) emissions can lead to severe environmental and human damages. To quantify these reactive N emissions the Nitrogen Footprint (NF) can serve as a valuable indicator. This work is the first attempt to quantify an institutional NF in Spain and the first institutional NF of a research center. The NF of the Spanish research center of INIA was quantified for the year 2019 taking into account all N emission sources. The total NF of the research center INIA for 2019 was 9289 kg N and its NF per capita is 16.1 kg N per full-time equivalent population. The largest N emission sources were food (57%) and utilities (33%), while the least N loss was fertilization for groundskeeping (0.01%), and research plots (0.15%). Taking the NF of INIA as baseline the following strategies of N mitigation were analyzed: (1) beef replacement in the menu, (2) reduction of meat by non-meat sources, (3) reduction of beef, fish, and seafood by other protein sources, (4) improving the wastewater treatment efficiency, and (5) recycling food waste. This institutional NF approach serves INIA's institution as an indicator to quantify its N pollution and allows the identification of useful mitigation strategies to reduce the overall NF.