Key sustainability challenges for the global phosphorus resource, their implications for global food security, and options for mitigation

Global food security is a priority for the future development agenda of the United Nations. Given the high dependence of the modern global food production system on the continuous supply of commercial phosphorus (P) fertilizers, the goal of achieving global food security could be hampered by any form of paucity of the global P resource. P is a finite, non-substitutable, non-renewable, and geographically restricted resource. The anthropogenic influences on this critical resource are likely to pose a number of challenges to its sustainability. Based on an in-depth and systematic review of recently published literature, this study presents a detailed, methodical, and up to date assessment of the key sustainability challenges for the global P resource, and highlights their implications for global food security. The assessment indicates that the demand for P fertilizer to produce enough food for the growing global population will substantially increase by the middle of this century. There are also significant discrepancies in estimates of the lifetime of global phosphate rock (the main source of chemical P fertilizer) reserves that range from a few hundred to a thousand years; however, as global reserves deplete, exploitation of, and exploration for, resources will replenish reserves although the global P resource is finite. The signs of geopolitical constraints regarding phosphate rock reserves are already evident, and are likely to be more intense in future. The combined impact of increasing demand, dwindling reserves, and geopolitical constraints could result in a substantial decline in the production and supply of chemical P fertilizer in the global market and lead to an increased P price, and this situation may eventually restrict the access of farmers of many countries to P fertilizers for food production. Moreover, there is evidence of significant P wastage and loss as well as high discharge to water bodies from various systems at different geographical scales. The wastage and loss of P in this manner, if not checked, will not only increase the global demand for P but also result in the increased depletion of global phosphate rock reserves. On the other hand, the continuing high discharge of P to water bodies will accelerate harmful processes such as algal bloom, hypoxia and eutrophication that deplete fish and other aquatic foods, the signs of which are already apparent, and may cause irreparable damage to aquatic ecosystems. Shortage in supply of fish and sea foods in turn will restrict the access of many people to a protein based diet, and eventually result in hunger and malnutrition; however, this important fact is often overlooked while addressing the significance of sustainable P management for global food security. We recommend that any policy at the international, national, and local levels that aims to achieve food security and to protect aquatic ecosystems should incorporate measures to address the key sustainability challenges for the global P resource. An overview of the recent advances in the knowledge of sustainable P management strategies as presented in this study could be effectively utilized to mitigate these challenges for achieving global phosphorus security, food security, and environmental sustainability.