Agriculture is facing a major challenge of feeding the growing world population. Since the green revolution, the abundant use of fertilizers has been widely regarded as a fundamental tool to address this challenge. Switzerland’s agriculture, on average, has used excessive amounts of fertilizers at relatively low efficiency, indicating the need to improve the nutrient use efficiency of Swiss agricultural production. In this article we present a thought experiment on how to close nitrogen- and nutrient-cycles in Swiss agriculture and thus foster a more sustainable fertilization.