Phosphorous, an element required for plant growth, is incredibly important for our food system, but also a costly pollutant and a limited resource. Understanding how the element moves through the food system and where inefficiencies occur are critical for a sustainable food system in the face of a growing population, climate insecurity, and resource depletion.
Researchers from the University of Birmingham conducted a substance flow analysis, based on the inputs, stocks, usage and flows, and outputs of phosphorus in the United Kingdom’s (UK) food system. The study was recently published in Resources, Conservation, and Recycling. The team examined existing literature and government data reports, using 2009 as the base year, given the availability of a nearly complete dataset.
Given that matter can only be transformed and not destroyed, data on phosphorous inputs and outputs at different points in the system indicate the existences of inefficiencies in a given systems, such as pinpointing how and where phosphorus enters a system and how much comes out at the end of its use. The authors analyzed the annual flow of phosphorous in 25 categories, from fertilizer application to recycled sewage waste. The UK relies on phosphorus imports for food, feed products, and fertilizers from the US, China, and Morocco due to the lack of native reserves. The team realized evidence of loss and accumulation of phosphorous in the food system.
Accumulation of phosphorous in agricultural soils is believed to be mostly the result of animal manures, which accounts for 62% of the total phosphorous inputs to agricultural soils. Manure application can reduce the need for imported mineral fertilizers. However, improper application increases phosphorus accumulation in the soil, and subsequent mineral loss and waste in the form of pollution and eutrophication.
By identifying the flow of phosphorus, the researchers were able to identify points of phosphorus depletion and accumulation, which provide opportunities for improving the food system. The authors conclude that if stocks and flows of phosphorus could be reduced effectively, the UK could reduce its reliance on phosphorus imports. Tightening the use of nutrient inputs in a food system can result in decreased dependence on imported resources while reducing environmental pollution.