Conserving essential P for future UK food security


2 October 2018 17:42
Professor Paul Withers

Professor Paul Withers has changed the way we look at phosphorus (P), a nutrient essential for the health of plants and animals, and vital for increasing UK food production.

“For decades, farmers have been encouraged to ‘feed the soil to feed the crop’ a philosophy which advocates over-generous applications of phosphorus fertiliser to our soil to avoid any risk of there not being enough for crops,” said Paul, who has recently joined the Lancaster Environment Centre as Professor of Catchment Biogeochemistry. 

“But a lot of unused phosphorus gets stored in the soil, and can then be washed away and lost whenever it rains, which has a serious environmental impact and is very costly.”

This lost phosphorus ends up in watercourses, causing eutrophication which is commonly observed as algal blooms, release of harmful toxins, oxygen depletion and loss of biodiversity.

“Another concern is that we are exploiting too rapidly the natural and finite resource of phosphate rock, from which all phosphorus used in society is manufactured. This means the UK is entirely dependent on phosphorus imports from the few other countries holding this essential resource” said Paul.

“So we have been developing a new more sustainable phosphorus paradigm called ‘Feed the crop not the soil’, which focuses on how much phosphorus is actually getting into the crop, rather than staying in the soil or being lost through runoff and leaching.

“The tricky bit is trying to predict a crop’s phosphorus requirement and applying phosphorus in an efficient way so that less gets immobilised by soil and more gets taken up by crops.”

Solving this tricky problem is one of the aims of a major research project which Paul is leading, ‘The role of phosphorus in the resilience and sustainability of the UK food system’, or RePhoKUs for short. It brings together multi-disciplinary researchers from across the UK and Australia with food producers, manufacturers and retailers.

A key part of the project aims to explore why some river catchments retain phosphorus better than others.

“We don’t currently understand what characteristics confer this buffering quality or how we can create or augment this quality by better managing the landscape,” says Paul.

“If we can identify which catchments are really leaky, maybe we don’t want to grow things there, and if a catchment is highly buffered (retains phosphorus) maybe that’s where we want our farming to get even more intensive.”

RePhoKUs is also carrying out the first UK wide study to measure the country’s vulnerability to a future scarcity of phosphorus. It will explore whether phosphorus can be recycled from secondary sources, such as struvite recovered from waste water or phosphorus stored in the soil, and how much phosphorus might be made available this way.

To increase the impact of the research, social scientists at Leeds University and the University of Technology, Sydney are exploring what would make farmers, consumers and retailers adapt their practices to take into account any new approaches that come out of the research.

Paul, who has moved from Bangor University and will be working part-time at Lancaster, has an ideal background to lead this research, having both hands on and academic experience of food production.

His mother was a farmer’s daughter, and he spent his childhood summers on family farms in North Wales. After studying at agricultural College, Paul started work on a farm. Then an opportunity to join the civil service’s soil science department caught his eye and changed the course of his career.

The civil service funded Paul to go to university to do a degree in Soil Science, and he continued his career in the then Agricultural Advisory and Development Service (ADAS) as an on-farm advisor and research scientist. He gradually became more and more fascinated by research and the need to provide a solid unbiased science base for farmers.

In 1990, following an outbreak of huge algal blooms in the North Sea, Paul was asked by the Government to investigate the link between phosphorus and aquatic eutrophication: since then Paul’s research has focused on this important chemical, and how it is used in the food system.

In 2010, dissatisfied with the “profit driven ethos” created by the privatisation of ADAS, Paul left to join Bangor University in search of the opportunity to think more innovatively.

He moved to Lancaster University earlier this year attracted by “the opportunity to interact with a wider range of scientists involved in a wider range of issues around food security, social science and food science.”

He hopes to start “dreaming up” some new projects with his colleague Professor Phil Haygarth, who he has known for nearly thirty years, and is very interested in the work being done by Lisa Norton from the Centre for Ecology and Hydrology’s Lancaster laboratories into the links between nutrient use and biodiversity.

RePhoKUs involves researchers from Lancaster University, the Agri-Food and BioSciences Institute (Northern Ireland), the Centre for Ecology and Hydrology at Wallingford, the University of Leeds and the University of Technology (Sydney). It is funded by the BBSRC, ESRC, NERC and the Scottish government, and is supported by the N8 AgriFood programme and the UK Nutrient Platform who are contributing Knowledge Exchange expertise, stakeholder engagement and capacity.

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