Farmers now have to add sulphur to their soil because it's not falling from the sky
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Remember the good old days of acid rain?
Some plants do.
Efforts to reduce sulphur pollution in the air have been so successful that Southwestern Ontario farmers are being warned to watch for sulphur deficiency in their crops.
“That air pollution was actually free fertilizer for farmers,” Peter Johnson, an agronomist with Real Agriculture, said Monday.
“The effort to clean up the air has meant farmers now have to buy more fertilizer to grow their crops.”
Adding sulphur to the soil was a common practice for farmers in the 1880s, but Ontario growers didn’t have to think about it for decades because of the amount of sulphur that fell on the land each year from sources such as smelters, coal-fired generating plants and transportation fuels.
Johnson estimated about 30 pounds (13.6 kilograms) per acre of sulphur a year fell from the sky at the peak of sulphur pollution. That has now been cut to less than 10 pounds (4.5 kg).
Nationally, Environment Canada estimates the fight against acid rain cut Canada’s national annual emissions of sulphur dioxide from more than 3,000 kilotonnes in 1990 to slightly more than 1,000 kilotonnes by 2014, a 63 per cent drop.
Ontario, the biggest single sulphur polluter in 1990, had the most drastic cuts in the 15-year-period, according to Environment Canada, and now is second to Alberta. Manitoba was third largest.
The first recent signs of sulphur deficiency in crops were found in the London region about 2008.
In corn and wheat, sulphur deficiency typically shows up as a yellow appearance in the plants.
This year, the problem has been found in corn, wheat, alfalfa and canola, Johnson said, and is more widespread than he has seen before.
About the only crops that haven’t been found with sulphur deficiency are soybeans and edible beans — and that could change in future years as controls continue to reduce air pollution, he said.
Nobody wants a return of acid rain — responsible for killing lakes and damaging buildings — but farmers need to watch for sulphur deficiency and take action if they find it. Otherwise, they could face serious yield reductions, Johnson said.
“We can do something about it. Farmers need to get out there and apply sulphur.”
Cutting sulphur oxide air pollution
Environment Canada credited a 63% drop in emissions from 1990 to 2014 on:
- Technological upgrades and new air pollution controls for smelters
- Reducing emissions from and closing coal-fired power plants
- Improved emission controls in petroleum refining
- Introduction of low-sulphur fuels
