Sustainable strategies towards a phosphorus circular economy

Abstract

Society as a whole uses too much phosphorus (P). This is putting unsustainable pressure on finite reserves of phosphate rock (PR), causing widespread eutrophication of inland and coastal water bodies, loss of terrestrial and aquatic ecosystem services and raising some concerns over the human health risks of high P in the diet (Elser and Bennett 2011;Withers et al. 2015b). Recent papers suggest that the upper tolerable limit, or planetary boundary of unacceptable consequence for humanity, for the key threat of freshwater eutrophication has already been exceeded (Carpenter and Bennett 2011; Steffen et al. 2015). Controversies arise over the scarcity of PR (Scholz 2013; Ulrich and Frossard 2014), but what is clear is that in the long term there is no other solution to these pressing environmental issues, but to develop a circular economy for P, and close the P cycle through improved P recovery and recycling (Withers et al. 2015a). However, P use efficiency in the current food chain remains very low with numerous surpluses, losses and poor recycling loops. This situation is exaggerated by clear imbalances of P use that exist across the globe with too little P used in poor countries, and too much P used in the richer countries, either in the past or currently (MacDonald et al. 2011). With a growing population demandingmore food, bioenergy and clean water, and in relation to enhanced nitrogen (N) supply to ecosystems and lower water availability, these imbalances in P use will become more critical (Jarvie et al. 2015; Penuelas et al. 2013). Resolving this societal problem requires sustainable solutions to improving P use efficiency along the whole food chain, and specifically within agricultural systems since farming is the main driver of the global P cycle. A range of sector and stakeholder perspectives on different aspects of the P cycle in different geographical regions were presented at the 4th Sustainable Phosphorus Summit held in Montpelier (France) in September 2014. In this conference special issue, we bring together a diversity of papers that focus on some approaches to developing more sustainable P use in agroecosystems. This special issue pays particular attention to papers that tackled integrated or largescale approaches: from plant to planet, from genotype to governance, from farm to waste management and those including losses to the environment. We also include a paper from our young scientists that clearly put into perspective the need for integrated approaches to resolve the P problem. T. Nesme (&) ISPA, Bordeaux Sciences Agro, INRA, 33175 Gradignan, France e-mail: thomas.nesme@agro-bordeaux.fr