The nitrogen footprint of food products and general consumption patterns in Austria

In this paper we use nitrogen (N) footprints as indicators of potential environmental impacts of food production in Austria. These footprints trace the losses of reactive nitrogen (Nr), i.e. N compounds that are generally accessible to biota, in connection to the chain of food production and consumption. While necessary for food production, Nr is known for its negative environmental impacts. The N footprints presented here describe Nr losses but do not link to effects directly. In deriving N footprints, Nr lost along the production chain needs to be quantified, expressed as “virtual nitrogen factors” (VNF). We calculated specific VNF for Austrian production conditions for a set of eight broad food categories (poultry, pork, beef, milk, vegetables & fruit, potatoes, legumes, cereals). The life-cycle oriented nitrogen footprints for the respective food groups were replenished by assessing Nr losses related to energy needs and to food consumption. The results demonstrate that in general, animal based products are less nitrogen-efficient than plant based products. For meat, footprints range from 64 g N per kg (pork) to 134 g N per kg (beef). For vegetable products, footprints are between 5 g N per kg (potatoes) and 22 g N per kg (legumes). The detailed ranking of food products is different when relating nitrogen footprints to either simple mass of food, or protein content. Vegetables & fruit cause only 9 g N per kg, but 740 g N per kg protein, which is even higher than pork (616 g N per kg protein) or poultry (449 g N per kg protein). These differences clearly show that taking into account protein and other aspects of food quality may be crucial for a proper assessment of dietary choices. The total N footprint per Austrian inhabitant is dominated by food production and consumption (85%) but also includes other activities linked to fixing nitrogen from the atmosphere (notably combustion). The average N footprint is 19.8 kg N per year per Austrian inhabitant, which is on the lower end of a range of industrialized countries.