Phosphorus is commonly applied to crops in the form of phosphate fertilisers. But these are often inefficiently managed, Arno Rosemarin, senior research fellow at the Stockholm Environment Institute, told the Sustainable Phosphorus Summit 2014 last week (1-3 September) in Montpellier, France.
He said an estimated 80 per cent of phosphorus present in ores is wasted due to losses during mining, fertiliser application and crop harvesting.*
This pollutes waterways and wastes the finite supply of phosphate ores needed to make fertilisers, risking higher food prices, said Rosemarin.
“Phosphorus has not been a success story in governance,” he said. “[Scientists] have been talking about it for years, but there has been very little recognition of the problem.”
Good governance of how phosphorus is used in farming “is crucial because it is the limiting factor in most ecosystems that determines how much biomass can grow and it will determine the number of human beings that can be supported on Earth.”
Adopting agricultural practices that use extracted phosphate more efficiently will be key to maintaining reserves, said Stuart White, director of the Institute for Sustainable Futures at the University of Technology, Sydney, Australia.
“We have a lot of solutions already to improve efficiency, but there are institutional barriers which need to be addressed by policymakers,” he said.
One possible measure would be to use soil testing to ensure the correct amount of fertiliser is applied, said White.
Phosphorus could also be recovered from human or animal faeces and urine to complement the use of mineral-derived fertilisers, according to Yacine Badiane Ndour, co-director of the National Laboratory for Research on Plant Production in Senegal.
Such waste can be processed into organic matter suitable for applying to crops. Doing this improves soil quality and, through a series of chemical reactions, releases phosphorus trapped in the soil so that plants can absorb it — the result can be a tripling or even quadrupling of yields, explained Ndour.
This could help smallholder farmers who cannot afford phosphate fertilisers, she added.
“There are technologies right now that can transform human and animal waste to produce organic matter that could be reused by agricultural producers,” she said.
But global policies are needed to support regions with limited access to phosphate fertilisers in utilising them, said Ndour.
And while research can provide solutions, it will be up to policymakers to ensure equitable access to this nutrient, said White.
“Phosphorus will only get more expensive and more volatile in terms of its accessibility,” he said. “We need to ensure that every decision made and every policy initiative taken considers the issue of equity as well as the issue of phosphorus sustainability because these food security issues won’t be felt by people in developed countries but by the poorest of the poor.”
*This article was corrected on 11 September. It previously said that 80 per cent of phosphorus applied to crops in fertilisers was not absorbed by plants.