Save the P(ee)! The challenges of phosphorus sustainability and emerging solutions

Phosphorus (P) is a chemical element that is essential for all living things, playing a central role in genetic molecules, energetic metabolism, cell membranes, and even bones. Because its geological abundance on Earth and its weathering rate from rocks are low and it has relatively low mobility in soils, P is often limiting to the growth of living things, including algae in lakes and oceans and plants in terrestrial ecosystems, including crops. To overcome these limitations, humanity has massively increased the extraction of P from geological deposits for the production of chemical fertilizers, allowing for the greatly increased yields of the Green Revolution. However, this amplification of the P cycle has damaged aquatic ecosystems due to losses of P from fields, livestock rearing, and human settlements that have triggered toxic algal blooms and dead zones in lakes and oceans. Increasing demand for P fertilizer has also led to increasing and wildly fluctuating prices for phosphate rock, raising concerns about the long-term supply of P for food production. These two dimensions, uncertainty about availability of affordable P and concerns about water quality impacts, comprise the P sustainability challenge. A variety of strategies are needed to address these dimensions. These include improvement in crop varieties for more efficient P utilization, enhanced efficiency of fertilizer use on the farm, reductions in food waste, shifts in diet toward less meat consumption, and development of P recycling pathways to recover P from organic waste streams (food waste, manure, human waste). By advancing these approaches at a sufficient scale, society may be able to sustain both the food and the water it needs for a healthy future.