Phosphorus not scarce, just use wisely: expert

WINNIPEG — The president of the British Society of Soil Science says it’s time to stop talking about peak phosphorus because the crisis has been overstated and the issue doesn’t resonate with the public.

Phil Haygarth, a soil science professor at Britain’s Lancaster University, agreed that phosphorus is a limited resource, but he said the Chicken Little approach — that the sky is falling — isn’t accurate or effective.

He said reports of so-called peak phosphorus, which predict the earth has only 20 to 40 years of supply left are untrue.

“ … the truth is there are phosphate) reserves out there and there are arguments that the mineral reserves are relatively robust for a longer time,” Haygarth told the Canadian Society of Soil Science conference, a joint meeting of the Canadian Society of Soil Science and the Canadian Society of Agricultural and Forest Meteorology held in Winnipeg July 22-25.

The International Fertilizer Development Centre estimated a couple of years ago that the world has 60 billion tonnes of phosphate rock, a significant increase from earlier estimates of 16 billion tonnes.

Haygarth said there are also millions of tonnes of phosphorus in soil.

“All across the nations, there is earth P (phosphorus) stored in soils, there is actually quite a lot of phosphorus,” he said.

For example, estimates suggest that China has 930 million tonnes of phosphorus in its soil and that American soil contains 840 million tonnes.

The world’s mines produced 161 million tonnes of phosphate rock concentrate (processed ore) in 2008. Assuming a phosphate grade of 30 percent in the concentrate, it would mean that 48 million tonnes of phosphorus were extracted that year.

Therefore, the amount of phosphorus stored in U.S. and Chinese soil represents more than 30 years of global phosphate rock extraction.

However, Haygarth said it doesn’t mean the issue should be ignored.

“What I’m saying is let’s not forget that worry,” Haygarth said.

“Let’s use it as a little reminder to be more savvy and sensible in the way we use phosphorus … (because) it makes no sense to put it on the land and wash it into the oceans.”

For example, he said soil scientists should be studying ways to effectively harness the immense amount of phosphorus in the soil.

“There are opportunities for some biotechnology or some (plant) root solutions,” he said, noting that organic phosphorus in the soil is potentially available to plants.

“It’s there … and it’s just doing nothing. It’s not being used. What we need to do is start thinking about that.”

Haygarth also said it’s time to move away from discussions about peak phosphorus because the public and politicians aren’t listening.

“It’s just not a big enough deal when (compared) to things like poverty and oil,” he said following his presentation. He said a better way to get the public engaged with phosphorus issues is for soil scientists to link the crucial nutrient to social and environmental concerns, such as food security, water quality and waste.

Marla Riekman, a land management specialist with Manitoba Agriculture, said excessive nutrients flowing into Lake Winnipeg is an excellent example of Haygarth’s point.

Manitoba residents are extremely concerned about the health of the lake, which has spurred an effort to manage phosphorus more thoughtfully in the province.

“Even if it is (negative) that we’re dealing with Lake Winnipeg, there are a lot of benefits to be able to start working together,” said Riekman, a conference organizer.

“I’ve think we’ve got a major opportunity with being able to say something has happened…. The opportunity is there because we’re tying this (soil science and phosphorus) into all these different sciences and being able to work on this common goal of fixing the lake and dealing with climate change and all these things.”

Large algal blooms in Lake Winnipeg in the mid-2000s provoked media stories and a public perception that agriculture was primary responsible for the declining state of the lake.

Don Flaten, a University of Manitoba soil scientist and conference organizer, said hostility toward agriculture has subsided over the last several years.

“There was a discussion earlier in this debate about the war on phosphorus, and it almost implied there would be casualties and an ‘us versus them, kind of approach,” he said.

“We haven’t had as much of that rhetoric lately.”

Flaten agreed that the Lake Winnipeg crisis represents an opportunity to manage phosphorus more wisely, which will ultimately benefit farmers and society.

He said livestock feed is an example of a win-win opportunity.

“If we can reduce some of the excess phosphorus that goes into the diets of livestock and can improve the efficiency of feeding of that phosphorus, we can save the farmers money … and we can reduce the amount of phosphorus in the manure.”

However, Flaten wasn’t sold on Haygarth’s idea of extracting phosphorus that exists within the soil.

He’s more comfortable with trying to cycle phosphorus more efficiently in the soil.

“That might be an excellent way to reduce phosphorus in the runoff … instead of that brute force approach of having a huge amount of phosphorus on our landscapes.”

About the author



Stories from our other publications