Future dietary changes will increase the global demand for agricultural resources per person. Food production requires several resources which are interrelated: land, water, nutrients and energy. Other studies have calculated the per capita requirements of only one resource (nitrogen or land). In this paper, we combine several parameters (diets, production systems and nitrogen-land trade-off) in one analysis in order to provide a more integrated assessment of the impacts of the use of agricultural resources for food. We estimated the trade-off between the per capita use of synthetic nitrogen fertilizer and crop land. With our methodology, we are able to identify separately the impacts of the type of diet and of the type of production system. We use national level data of five countries as examples of global extremes: from extensive to highly intensive systems, and from very basic diets to very affluent diets. The present differences in diets and production systems result in large differences in the per capita use of resources which ranges from 3 to 30 kg of nitrogen fertilizer use per person, and from 1800 to 4500 m2
of arable land use per person. As the results show, in 2050, the average per capita availability of crop land will not be enough to produce food for affluent diets with present production systems. Our results are useful to assess future requirements of nitrogen fertilizer for the limited land available on the planet.
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