A large American study has found genetically modified crops have dramatically increased the amount of herbicides applied to soybeans.
As well, data from Alberta suggest that GM crops have had an even greater impact in Western Canada, as the amount of herbicide sold in the province nearly doubled from 2003 to 2013.
The provincial government, through Alberta Environment and Parks, has tracked pesticide sales since 1993.
The department publishes a report every five years and its last round of sales data is from 2013.
That report was published in August of 2015 and it came to several conclusions:
- In 2003, herbicide sales in Alberta were 7.2 million kilograms of active ingredient.
- In 2013, herbicide sales were 13.2 million kg.
- Most of the increase is attributable to glyphosate, the active ingredient in Roundup.
- Glyphosate sales in 2003 were 3.3 million kg, 6.1 million kgin 2008 and 8.7 million kg in 2013.
Neil Harker, an Agriculture Canada weed scientist in Lacombe, Alta., got his first look at the pesticide sales data Sept. 26 and hadn’t had time to delve deeper into the data.
He wasn’t shocked, but he said it is concerning.
“I guess I’m surprised at the size of this jump in glyphosate. But I’m not surprised… that glufosinate is number three (in sales),” he said.
“I think a lot of this is not that we’re using pesticides more often, as much as we’re going to canola way more than we used to. We used to be in a four-year rotation, then it went to three years and now the most common rotation … is canola/wheat.”
The Alberta data is in line, somewhat, with research from the University of Virginia published in September.
In what’s being touted as the largest ever study on GM crops and pesticide use, U of V scientists analyzed survey data from more than 5,000 corn and 5,000 soybean growers in the U.S., from 1998 to 2011.
“The fact that we have 14 years of farm-level data from farmers all over the U.S. makes this study very special,” said Federico Ciliberto, U of V economist. “We have repeated observations of the same farmers and can see when they adopted genetically modified seeds and how that changed their use of chemicals.”
Ciliberto and his colleagues cited several key points:
- Growers of GM soybeans used 28 percent more herbicide than farmers who planted non GM soybeans
- Growers of GM corn used 1.2 percent fewer herbicides and 10.4 fewer insecticides than farmers who didn’t adopt the technology
Ciliberto said U.S. soybean farmers are now applying more herbicides to control resistant weeds.
“(After the introduction of GM crops) there was a reduction in herbicide use, but over time the use of chemicals increased because farmers were having to add new chemicals.”
As for the increased use of herbicides in Alberta, the expansion of canola may be a large factor in the story. Canola acres were 3.3 million in 2003, 5.2 million in 2008 and 6.2 million in 2013.
But not all of those acres are Roundup Ready canola, as varieties with tolerance for glufosinate and other herbicides are popular with growers.
So other uses, such as pre-harvest application, may have caused glyphosate sales to increase from 6.1 million kg in 2008 to 8.7 million kg in 2013, a rise of 42 percent.
Harker said it’s difficult to speculate because the Environment and Parks report focuses on sales, not use.
Nonetheless, the boom in herbicide use is worrisome.
“Even for people in agriculture it’s a bit concerning,” he said. “We’ve got weed resistance becoming a major issue… and we’d like to think one of the things to slow it down … is to use herbicides a little less. It doesn’t appear we’ve gotten there in any way, shape or form.”
The U.S. study has generated a number of media reports, focusing on how GM crops have increased herbicide use in soybeans. But those headlines don’t tell the entire story, said Ian Affleck, CropLife Canada managing director of science and regulatory affairs, plant biotechnology.
Affleck said most media reports ignored a crucial line in the paper’s abstract. Yes, overall use on soybeans has gone up but the herbicides applied to GM crops are less toxic.
“When pesticides are weighted by the environmental impact quotient, however, we find that (relative to non-adopters) GE adopters used about the same amount of soybean herbicides,” the paper said.
As well, the U of V study didn’t account for other environmental benefits of GM crop production.
“They didn’t take into account the benefits these technologies provide, in relation to support conservation tillage and how that reduces greenhouse gas emissions, protects soil erosion,” Affleck said.
It may be correct that GM crops have promoted the use of safer herbicides and there are broader benefits to society.
But those messages can be difficult to convey when the public sees data that herbicide sales doubled in Alberta from 2003 to 2013 and glyphosate sales nearly quadrupled between 1998 and 2013.
Harker agreed that glyphosate is less toxic but the ag industry shouldn’t shrug off the boom in herbicide use.
“I wouldn’t want to brush the whole increase over and say it’s a good thing,” he said. “I would rather see it not continue to increase.”