Meat consumption linked to global phosphorus use

McGill University research | Phosphorus not only input to increase

The results of a study that links increased meat consumption to the growing global demand for phosphorus didn’t surprise Genevieve Metson.

She said her findings illustrate the role diet can play alongside efficient farming and waste management to protect waterways and manage the Earth’s non-renewable supply of mined phosphorus for fertilizer.

“It’s not that surprising because our message is extremely similar to how we view other resources,” said Metson, the study’s lead author and a PhD candidate at McGill University.

“Eating a meat intensive diet also requires more water. It requires more nitrogen. It requires more land. So I think it’s a very synergistic message.”

Her study found that almost three quarters of the phosphorus used in the world can be traced back to meat production.

She measured the “phosphorus footprint” of nine crops and five animal product categories around the world, using fertilizer application rates to estimate the phosphorus required to produce crops and feed between 1961 and 2007.

The paper, published recently in Environmental Research Letters, found that a growing worldwide population, consuming more meat and calories, saw the global demand for phosphorus grow almost 200 percent over the period. She measured the growing demand per person at 38 percent, driven by increased meat consumption.

Metson and her co-authors found beef to be the most phosphorus intensive meat.

“The paper isn’t saying everybody needs to become a vegetarian tomorrow,” she said.

“It’s just saying that it’s true that it does require more resources and it’s an important factor to consider in how phosphorus resource demand might change in the future if dietary patterns across the world also change.”

The study found that developed countries had the highest demand, with the United States and Canada near the top of the list, while China’s per capita phosphorus footprint increased almost 400 percent over the period alongside the country’s changing wealth.

Canadians were demanding 5.86 kilograms of phosphorus per capita in 2007, says the study.

Estimates on the world’s supply of phosphorus vary from decades to hundreds of years, but Metson said the fertilizer is a non-renewable resource that’s not evenly distributed around the world, making judicious management a priority.

“I think that this paper shows that individual consumers do have a role to play in sustainable phosphorus management, and part of that role is in their dietary choices, but in Canada we also need to be looking at how we’re producing food and how we’re recycling organic waste that’s high in phosphorus,” said Metson.

“It’s not just the farmer that has the capacity to affect how we manage things, but it’s only one tool in a long tool kit to make phosphorus management in the food system be a little more conducive to clean waterways and food security in the long term.”

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