Arable crops need an average of 50-100 kg of phosphorus per hectare, according to Fertilizers Europe. This essential nutrient is important for root development. And while it is present in organic fertilizers such as crop residues, animal manure and slurry, global agricultural production is currently dependant on the addition of mineral phosphorus, which is extracted from phosphate rock for use in crop fertilisers, livestock feeds and food additives.
However, scientists warn in a new report, skyrocketing fertiliser prices in recent months underline that global mismanagement of this finite essential nutrient is ‘causing twin crises’ that are hitting water quality and food security.
In what the authors describe as the most comprehensive analysis of the phosphorus crisis to date, the Our Phosphorus Future report takes a detailed look at the global challenges caused by our current use of phosphorus. It was written by a team of 40 international experts from 17 countries, led by the UK Centre for Ecology & Hydrology (UKCEH) and the University of Edinburgh. It is supported by the United Nations Environment Programme (UNEP).
High phosphorus prices threaten food security
The report warns global food security remains threatened as farmers struggle to afford sufficient phosphorus fertiliser for their crops.
Five countries control 85% of the world's phosphate rock reserves - Morocco, China, Egypt, Algeria and Syria. This leaves the market exposed to what the report describes as ‘massive fluctuations’ on costs and supply – largely linked to political disruption, trade wars and escalating fuel prices. Since 2020, for example, the prices of both phosphate rock and fertiliser have increased by around 400%.
“Many countries are highly dependent on imported phosphorus fertiliser for food production, leaving them exposed to fertiliser price fluctuations,” observed Professor Bryan Spears of UKCEH, one of the lead authors of the paper.
Instability in the phosphate market exacerbates the impacts of other global factors influencing fertiliser costs, such as the effect of the war in Ukraine on the cost of natural gas.
Failure to manage waste phosphorus hits water quality
On the other hand, the overuse of fertilisers and sewage pollution pump millions of tonnes of phosphorus into lakes and rivers each year. This damages biodiversity and affects water quality.
Too much phosphorus can cause increased growth of algae and large aquatic plants, which can result in decreased levels of dissolved oxygen– a process called eutrophication. Large growths of algae - algal blooms – can also produce toxins that are harmful to animals and humans who come into contact with contaminated water.
The cost of responding to water-based phosphorus pollution in the UK alone is estimated at £170 million per year, the researchers stressed.
By the numbers: How phosphorus failures are playing out in the UK
Multiple countries around the world are impacted by our systematic failure to manage phosphorus. But zoning in on one – the UK – illustrates the scale of the problem.
UK food security is dependent on reliable supplies of phosphorus to fertilise agricultural soils and for use in animal feeds. The country imports around 175,000 tonnes a year. Shockingly, 57% of this is wasted, researchers found. That’s enough phosphorus to grow food for the entire population of London.
More than 26,000 tonnes of phosphorus is lost to UK waters each year. Some 75% of lakes and 54% of rivers in England failed the EU Water Framework Directive phosphorus standards for good ecological status.
What can be done? Adopt a ’50,50,50’ goal
The authors of Our Phosphorus Future want to see governments stepping up action and taking a pro-active approach to combatting the problem of phosphorus mismanagement.
“So far, there has been a lack of intergovernmental action. By providing the scientific evidence that shows threats posed by unsustainable use of phosphorus, as well as putting forward solutions, we hope our report will catalyse change towards sustainable management of this essential nutrient,” explained Dr Will Brownlie, a University of Edinburgh freshwater scientist who coordinated the report.
The scientists call on governments across the world to adopt a '50, 50, 50' goal: a 50% reduction in global pollution of phosphorus and a 50% increase in recycling of the nutrient by the year 2050.
This can be achieved through agricultural practices including the integration of livestock and crop production so phosphorus in animal manure is applied to crops, reducing the demand for chemical fertilisers.
The scientists also suggest that changes are needed in how we consume food and are calling for a shift towards ‘most sustainable diets’ and a reduction in animal protein consumption that would ‘reduce the amount of phosphorus needed to grow animal feed’.
With around a third of the food currently produced wasted, tackling waste would also mean ‘less demand for crops and animal products’, the researchers added.
Finally, better wastewater treatment could allow phosphorus to be removed from sewerage and reused – instead of being allowed to pollute waterways. In addition to delivering environmental benefits, this would reduce the reliance of the agri-food sector on the concentrated and volatile phosphorus markets, providing a boost to food security and the sovereignty of agricultural production.
“More efficient use of phosphorus in agriculture and increased recycling, for example from wastewater, can increase resilience in the food system while reducing pollution of lakes and rivers that are biodiversity hotspots and important for drinking water supply,” Professor Spears suggested.
Better phosphorus management for economic gains
The report’s authors estimate adopting the '50, 50, 50' goal would create a food system that would provide enough phosphorus to sustain over four times the current global population.
They believe that ensuring phosphorus is brought back into the production chain - rather than being left to pollute watersheds - could also save farmers nearly US$20 billion in annual phosphorus fertiliser costs. This would avoid a projected yearly clean-up bill of over US $300 billion to remove phosphorus from polluted water courses, they stressed.
Isabelle Vanderbeck of the United Nations Environment Programme, a co-author of the report, called on governments to take ‘decisive action’ to capitalise on this opportunity. “UNEP recognises the complexity of the nutrient challenge and the potential for economic benefits of improving phosphorus sustainability. Governments should take decisive actions to avoid significant environmental and societal harm due to phosphorus mismanagement," she said.