Strait of Hormuz disruption exposes the UK’s fertiliser vulnerability

When geopolitical shocks hit households, we tend to notice energy prices first. But another shock often follows quickly: fertiliser price spikes that raise farm costs, then food prices. This dynamic is now playing out following disruption to shipping through the Strait of Hormuz. In the backdrop of tremendous suffering of the people living in the war zone and the shaking of the global economy, the urea price has gone up by 50% within four weeks into the war. This is thanks to the disruptions to the Strait of Hormuz which is responsible for ~30% of global fertiliser trade from the Persian Gulf to other regions, along with ~ 20% of liquified natural gas (LNG), a key fertiliser feedstock, and 27% of globally traded oil. The shocks have already been clearly felt by farmers, including those in the UK. Even if the conflicts end soon, the impact on food prices is already inevitable, with the Food and Drink Federation expecting UK food inflation to reach at least 9% before the end of the year. 

Unfortunately, the above story of fertiliser supply chain crisis is not a rare event.: Only a few years ago, back in 2022, a similar episode of fertiliser price spike followed the outbreak of the Ukraine war, mainly triggered by the high energy prices, which led to a range of emergency responses by Defra to ease the pressure on UK farmers. As a slightly more remote example, exceptionally high fertiliser prices were behind the global food crisis in 2008, caused by a combination of high oil prices and the US rush to biofuel crops. 

As many would agree, the vulnerability of the farming sector to the disruptions to the fertiliser supply chain is rooted in the deep dependence of modern agriculture on chemical fertilisers, which are globally supplied commodities produced through energy-intensive processes. To make the sector more resilient in the UK, two interconnected questions naturally follow:  

• Can we lower the fertiliser input per unit food output?  

• Can we reduce import of foreign fertilisers to sustain the operation of the sector? 

To answer these questions, it is important to develop a solid understanding of how nutrients such as nitrogen (N) and phosphorus (P), supplied by fertilisers and essential for growing crops, are managed currently and how they can be utilised more efficiently, so that the farming sector becomes less dependent on chemical fertilisers.   

In one of the earlier Sprints in the Agile programme, we shed some light on this issue through a regional lens, particularly focusing on nutrient retention in organic waste management. Through mapping organic material flows in the region of Leicestershire county and Leicester city, we estimated that out of about 4000 and 700 tonnes of N and P embedded in the annual flows of wastewater, green waste and food waste, less than 10% is retained in the form of solid digestates and compost that can potentially be applied as fertilisers; most of the rest is “lost” through the discharge of treated wastewater.  

This local picture of a subset of nutrient-bearing flows is consistent with the larger picture at the national level: Annually ~700 kt of N and ~25 kt of P are discharged into UK’s water systems, equivalent to about 70% and 50% of UK’s total N and P input by chemical fertilisers.  

Drawing on the regional mapping of the current system and through working with stakeholders, our Sprint further identified key actions towards more circular use of nutrients to reduce the reliance on external supply of chemical fertilisers, lower economic costs and avoid adverse environmental impacts. These actions include near-term possibilities such as improving the technology and practice of anaerobic digestion towards a more nutrient efficient method for organic waste valorisation, and behavioural changes to reduce plastics contamination to the recycled organic waste (food waste in particular) to enhance the quality of recovered nutrient-rich products.  

On the other hand, to significantly improve nutrient circularity, we recognised the necessity of more fundamental changes that may require structural overhaul, such as developing and adopting upstream wastewater solutions to allow nutrients to be captured before they enter a centralised treatment system and become highly diluted.   

Beyond technical measures, what also emerged from our Sprint is that whilst many stakeholders recognise the importance of nutrients management for farming and environmental protection, there is currently no suitable organisation to lead the creation and implementation of holistic organic waste management and resource recovery across domestic/public, agricultural, industrial and commercial sectors. Therefore, national and local stakeholders need to collaborate to eventually establish such an organisation or mechanism, through either giving an existing body new power/capacity or by creating a new body. Together with required regulatory changes, we hope that such efforts can provide institutional readiness to implement the desirable transformation. 

In summary, while our Sprint identified some low hanging fruit for improving the use of nutrients and fertilisers, it became quite clear that significant technical and institutional changes to the current system are required to fundamentally enhance resource circularity and ease the dependence of the food system on chemical fertilisers.  

Effecting such fundamental changes will require long-term vision and determination, which are not necessarily easily attainable in today’s political and socioeconomic environment. Until we have managed such changes, we are likely to be repeatedly reminded by the Hormuz-like pain. Hopefully, such an unpleasant projection will add to all the positive forces, which will eventually move the world towards the progressive direction of resilience, sustainability, and peace. 

Prof Aidong Yang is Professor of Engineering Science at the University of Oxford and the Agile Lead for Capacity Building and Training.