Where does Sweden’s nitrogen go? Building a comprehensive national nitrogen budget

Abstract We present Sweden’s first comprehensive National Nitrogen Budget (NNB), quantifying reactive nitrogen (Nr) inputs, outputs, and intersectoral transfers across eight key subpools, including agriculture, energy, industry, and waste. For the reference year 2015, we estimate that approximately 848 kt N entered Sweden in reactive forms, primarily through import of goods, ‘import’ of air pollution from upwind areas outside Sweden, and from nitrogen fixation. We estimate that 269 kt Nr is annually released to atmosphere or hydrosphere as a pollution, while 311 kt N is converted back to inert N 2 gas. The analysis identifies nitrogen losses to the environment, and opportunities for improved nitrogen use efficiency across sectors. The Swedish NNB is compared to calculations done for Austria, Germany and Switzerland. The study contributes to international efforts to harmonize nitrogen accounting and strengthen transboundary environmental governance.