Call to tackle phosphorus impact on food and water security

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Scientists have called for action to be taken to tackle poor management of phosphorus which they say is worsening food and water security.

The finite nutrient is extracted from phosphate rock and is an essential element in fertilisers to grow food and to increase crop yields to feed the growing population.

But a scientific report released on Thursday shows poor management of phosphorus is leading to food shortages, with farmers struggling to afford sufficient fertiliser.

Meanwhile, overuse of the nutrient pumps millions of tonnes of phosphorus into lakes and rivers each year, having a devastating impact on biodiversity in freshwater eco-systems.

Dr Will Brownlie, a University of Edinburgh (UoE) freshwater scientist who co-ordinated the Our Phosphorus Future report, said recycling the nutrient to reuse it in fertilisers is one of the essential solutions to solving the crisis.

The report calls for a 50:50:50 goal – a 50% reduction in global phosphorus pollution and a 50% increase in the recycling of phosphorus lost in waste by 2050.

Dr Brownlie said: “If we do this, we will return 8.5 million tonnes of phosphorus to our farms that could support a food system that could provide enough food for four times our population.

“We would save the global farming community 20 billion dollars in annual fertiliser costs that they would have been paying… but if we were to stop them, it would cost us 300 billion dollars to fix.”

He said reaching this goal would also provide enough phosphorus to sustain more than four times the current global population.

In the UK, 26,000 tonnes of phosphorus is lost to UK waters each year, which means 75% of lakes and 54% of rivers are failing phosphorus standards.

The crisis is costing the country £170 million in pollution costs and £265 billion on a global scale.

In England, it is the primary cause of water quality impairment, and across the world phosphorus pollution drives one of the greatest biodiversity losses in biomes and freshwater ecosystems, the report said.

The document, which has been led by the UK Centre for Ecology and Hydrology (UKCEH) and UoE, has come up with 10 key actions to put to international governments to tackle the issue.

These include reducing global food waste, meaning less demand for crops and animal products, and therefore phosphorus.

Promoting a global shift to a healthy diet with a low phosphorus footprint has also been recommended.

Dr Brownlie said this would be similar to a diet used to reduce impact on climate change – one higher in vegetable protein and one that reduces the amount of phosphorus needed to grow animal feed.

Reporting and assessment of the impact of phosphorus on freshwater and coastal ecosystems also needs to be improved, the report said.

For example, knowing exactly where algae blooms are happening which, when found in lakes, ponds and reservoirs, can be a sign of phosphorus pollution.

These blooms produce toxins that are harmful to animals and humans who come into contact with or consume contaminated water.

Professor Bryan Spears of UKCEH, one of the lead authors of the report, said geoengineering has been used to control the phosphorus pollutant in freshwater areas by adding chemicals that extract it, but this is not a sustainable solution.

He said: “This method removes phosphorus from the food system, but what we need to do is to recover it and reuse it for the food system to make it more sustainable.”

In terms of the annual supply of phosphate rock, just four countries were responsible for 72% of global production in 2021: China (39%), Morocco (17%), the US (10%) and Russia (6%), leaving the market exposed to massive fluctuations in costs and supply due to political disputes, trade wars and escalating fuel prices.

Since 2020, for example, the prices of both phosphate rock and fertiliser have increased by around 400%, according to data, and continue to rise.

Scientists said this instability 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.

Prof Spears said: “Many countries are highly dependent on imported phosphorus fertiliser for food production, leaving them exposed to fertiliser price fluctuations.

“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.”

Dr Dana Cordell, research director at University of Technology Sydney, discussing the report, said some large fertiliser companies have shown interest in using recycled phosphorus, but they want more security.

“It’s not about disinterest,” she said, “it’s about the quantity and having a secure supply.

“These are commercial operations.

“They don’t want to hear about a few tonnes, they want a hundred tonnes.”

Dr Brownlie said: “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.”

Isabelle Vanderbeck of the UNEP, a co-author of the report, said: “Governments should take decisive actions to avoid significant environmental and societal harm due to phosphorus mismanagement.”

A spokesman for the Department for Environment, Food and Rural Affairs, said: “Phosphorus pollution into our rivers has reduced by 67% over the last two decades.

“We have proposed setting long-term targets in our Environment Act to further reduce phosphorus pollution from agriculture by 40% and from wastewater by 80% by 2037.”

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