Image: G. K. MacDonald, E. M. Bennett, P. A. Potter, N. Ramankutty
The map above is the first illustration of worldwide imbalances in the use of phosphorus, a key component of fertilizers and an essential plant nutrient. “Typically, people either worry about what happens when an excess of phosphorus finds its way into the water, or they focus on what happens when we run out of phosphorus,” said Graham MacDonald, lead author of the McGill University study. “This is the first study that illuminates the issue on a global scale and suggests that these are not separate problems… that the issue is one of distributing the phosphorus we’ve got.”
From the press release for the study:
The study used detailed agronomic information about how much phosphorus is applied to soils in fertilizers and manures for more than 100 different food, feed, and fibre crops produced around the world in 2000. The results point to large imbalances in phosphorus use, with both the overuse of phosphorus in some parts of the world and phosphorus deficits in others.
The biggest surprise turned up in the fact that entire regions do not come with surpluses or deficits of phosphorous, but rather that levels vary within regions — “with surpluses and deficits commonly occurring side-by-side in a single region.”
We know that over-use of fertilizers around the world is bringing serious problems to the world’s ecosystems: ocean dead zones to decreased grassland biodiversity to health problems like reproductive toxicity.
MacDonald said, “Until you can quantify how phosphorus is actually currently being used, it’s difficult for policy-makers to go ahead and make informed decisions at a national or global scale.”
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