Phosphorus a problem in which we all play a part

Hey there, time traveller!
This article was published 14/09/2019 (2286 days ago), so information in it may no longer be current.

If you asked the average person on the street what his or her view is of the phosphorus situation in Manitoba, chances are you’d hear back it’s a pollutant.

The general sense is that the nutrient, called P by soil scientists, is largely responsible for the declining health of major water bodies such as Lake Winnipeg because it feeds toxic algae blooms that gradually choke out all life.

It’s true. There is too much phosphorus flowing into Lake Winnipeg, and there’s lots of finger-pointing as to why.

Folks who don’t like intensive hog production condemn pig producers. Those who are skeptical of modern crop-farming practices blame grain farmers.

People living on farms say urbanites are responsible, because inadequate sewage treatment systems allow excessive amounts of nutrients and other contaminants to escape.

Or it’s those inconsiderate blokes putting P into the water upstream from Manitoba.

“In reality, P loading to water bodies such as Lake Winnipeg comes from a large number of small sources — natural, urban and rural — throughout the watershed. So as one of our fishers on the Lake Winnipeg Stewardship Board used to say, ‘If you want to see who’s loading P into Lake Winnipeg, look in the mirror,’” says Don Flaten, a University of Manitoba soil scientist.

If you break down the sources of phosphorus contamination, Flaten says the latest estimates he’s seen suggest one-third comes from natural sources, one-third comes from cities and towns and one-third comes from agricultural activities.

The fertilizer industry and extension workers have been aggressively promoting what’s known as 4R nutrient management — applying the right source, at the right rate, at the right time and in the right place — as a way to save the environment, improve crop yields and save farmers money.

The political will to tackle urban culpability is less apparent, partly because it typically requires large capital expenditures. Who’s going to vote for politicians promising to raise taxes so they can manage sewage more sustainably?

However, as sure as too much P in the wrong places is a problem, it is also true phosphorus is a non-renewable resource and some researchers are sounding the alarm about declining global reserves.

This coming week has been declared Phosphorus Week in recognition of the element’s discovery 350 years ago.

Scientists are using the opportunity to get P out of the gutter, so to speak. Treating phosphorus as simply a waste product to be flushed away not only hurts the environment, it threatens global food security.

In a new paper to be released in the Frontiers of Agricultural Science & Engineering Journal, researchers with Rothamsted Research in the UK don’t mince words.

“The continued supply of phosphate fertilizers that underpin global food production is an imminent crisis,” they write.

“The rock phosphate deposits on which the world depends are not only finite, but some are contaminated, and many are located in geopolitically unstable areas, meaning that fundamental changes will have to take place in order to maintain food production for a growing global population.”

Current estimates say the world has about 259 years of rock phosphate left at current rates of use. However, demand is rising rapidly. The estimate of remaining stores has dropped from 300 years in just three years, a decline of 14 per cent.

At that rate, “it could be argued that all supplies will be exhausted by 2040,” they say, although they acknowledge that scenario is unlikely.

More likely is increasing prices and rising political tensions.

“Rock phosphate deposits do not necessarily need to become depleted before the effects of scarcity on food production are noticed,” the paper says.

Many will pooh-pooh warnings like this. After all, a few short years ago, the pundits said the world was running out of petroleum energy sources, but those gasoline engines still start when it’s time to go to work every day.

Nonetheless, even if you don’t believe the world is running out of P, for the sake of the environment, it might be prudent for all of us to stop blaming each other for wasting it and start doing a better job of managing nutrients that help grow the food we eat.

Laura Rance is vice-president of content for Glacier FarmMedia. She can be reached at lrance@farmmedia.com.