Phosphorus recycling and food security in the long run : a conceptual modelling approach

Food security for all is a global political goal and an outstanding moral concern. The common response to this concern is agricultural intensification, which includes among other things increasing inputs of fertilisers. The paper addresses the fact that phosphorus (P) is essential for agricultural production but large and increasing amounts of P fertilisers stem from depletable mines. This raises sustainability concerns and the possibility of long-term food insecurity. The paper analyses three scenarios for global phosphorus extraction and recycling under discounted utilitarianism. First, for a benchmark scenario without recycling, food security will inevitably be violated in the long run. Second, if we introduce P recycling, food security can be maintained but food production falls over time and approaches a minimum level just sufficient to feed the global population. Third, a sustainable (i.e. non-declining) path of food production is feasible. Compared to just maintaining a minimum level of food production the sustainable path requires greater recycling efforts. Recycling efforts are increasing over time but the total discounted costs are finite and, hence, sustainable food production seems feasible even if it depends on depletable phosphate mines.