In Finland, while total agricultural production has remained relatively constant, nutrient input from industrial mineral fertilizers has declined over the past 20 years, which has been the target of environmental policies due to eutrophication risks. From 1996 to 2014, the use of nitrogen (N) declined by 18%, phosphorus (P) by 49%, and potassium (K) by 49%. However, at the same time, the international agricultural products trade has increased dramatically by mass (58%), and Finland has increased imports of food and feed products, such as, protein feeds, vegetables, and fruits. We analyzed the nutrient contents of foreign trade from 1996 to 2014 by using a substance flow analysis. We discovered that, when comparing nutrients contained in trade to the use of fertilizers, the trade of food and feed accounts for more than one-third (40%) of the fertilizer input to the Finnish food system. In 2014, 53 Gg of N, 8 Gg of P, and 15 Gg of K were imported due to trade, equating to 35%, 70%, and 45%, respectively, compared to the use of fertilizers in the food system. Declines in fertilizer inputs to crop production are partially offset by flows of plant nutrients from feed imports. In formulating agri-environmental policies targeting nutrient loading, more attention should be paid to national imports–export balances and, especially, to the spatial distribution of flows in feed trade.