Losses and efficiencies: From myths to data. Lessons learned from sustainable phosphorus management. Editorial

Loss management is efficiency management if we increase the output (product, outcome, yield, effect, value) in relation to an input (or reference set) of an action. The phrasing "we have to efficiently produce the right things" shows that efficiency is a means rather than an end. This special issue clarifies conceptual issues and misconceptions around losses and efficiency for the case of phosphorus, a non-renewable (i.e., finite) and essential mineral that is indispensable for food and life. The contributions focus on phosphorus mining, phosphorus fertilizer use, and the recycling of phosphorus from sewage and iron production. The current state and trends of losses and efficiencies in mining are presented and discussed, including low net use efficiency and total use efficiency. Papers on agriculture discuss the antagonistic relationships between yield (i.e., efficacy) and efficiency in fertilisation and the necessity to aspire to a calibrated nutrient balance, which also includes organic soil phosphorus pools. Papers on recycling sewage reveal that phosphorus recycling from sewage and iron/steel production is not only technologically possible but also may become economically feasible. A key message is that phosphorus management is a complex issue that includes misconceptions, fallacies, trade-offs and dilemmas. To overcome and properly cope with them, sustainable phosphorus management has to start from a comprehensive system model that includes both the flows and the actors. Contributions to material flow analysis show how this can become possible and how we may move from myths to data