Dietary trends behind higher phosphorus use

Between 1961 and 2007, rising meat consumption and total calorie intake resulted in a 38 percent increase in the world's per capita "phosphorus footprint", according to a research by Canada's McGill University.

The findings underscore a significant challenge to efforts to sustainably manage the supply of mined phosphorus, a non-renewable resource widely used as fertiliser, the journal Environmental Research Letters reports.

When phosphorus is lost through agricultural runoff or sewage systems, it can pollute waterways downstream. In addition, because deposits are heavily concentrated in a few countries, global supplies and prices for the resource are vulnerable to geopolitical tensions, according to a McGill statement.

"Our results demonstrate that changes in diet can be a significant part of the strategy for enhancing sustainability of phosphorus management," says Genevieve Metson, doctoral student in McGill's Department of Natural Resource Sciences, who led the study.

"In particular, reduced consumption of meat, and especially beef, in countries with large phosphorus footprints could put a big dent in demand for mined phosphorus -- since it takes many kilograms of feed, which is fertilized, to produce a kilogram of meat," adds Metson.

Metson and co-authors Elena M. Bennett from the McGill School of the Environment and James J. Elser from Arizona State University, computed phosphorus-footprint values based on annual country-by-country diet composition data from the Food and Agriculture Organisation.

They calculated the total amount of phosphorus applied to food crops for humans and animals by using fertilizer-application rates available through the International Fertilizer Association, among other sources.

"It is really remarkable how much influence changes in diet have had on our demand for this very limited resource," Bennett says.