Abstract: This article broaches the legal treatment of the non-substitutable nutrient phosphorus, which is indispensable for life. We not only address the case of a highly important resource problem that has hitherto received little attention in the political discourse, but also focus on the excessive and wasteful entry of phosphorus in the environment. It is the sum of multiple minor actions of phosphorus users, that can lead to ecologically and resource-related fatal consequences. We hence argue that it is not sufficient to increase efficiency in phosphorus uptake “per individual plant” if at the same time crop cultivation is expanded to previously unused areas, for instance for greater animal feed crop (due to a globally rising meat consumption) or bioenergy plant production. It will be impossible to achieve the necessary absolute phosphorus use reduction by that means. Technical solutions”, ”command and control” law and resource efficiency alone do not tend to solve resource problems or quantity problems if at the same time, (global) production increases or remains on a constant high level.