Doug Derksen holds up two potted plants inside a greenhouse at Agriculture Canada’s Brandon Research Centre.
Both pots hold hairy nightshade, a weed familiar to Manitoba farmers.
One plant is yellowed, its leaves curled and marred by dead spots.
The other plant is healthy, sporting lush leaves and more growth than its sickly counterpart.
The difference?
The sickly plant was deprived of sulfur while the other was not. Everything else, including the source of seed, was the same.
Derksen believes lessons can be learned by studying how weeds react to sulfur and three other nutrients commonly applied to western Canadian fields.
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The research scientist wants to know what methods farmers can use to get those nutrients to their crops without giving weeds a helping hand at the same time.
He and three other scientists with Agriculture Canada plan to study the relationship between crop growth, weeds, and nitrogen, phosphorous, potassium and sulfur.
It will be the first time in Western Canada that research has put that relationship under a microscope.
“We need to think about fertilizer management not just for the crop but how that influences the weeds in the field,” said Derksen, who has a keen interest in controlling weeds through an integrated approach.
“If we’re fertilizing in a way that favors more weeds, we’re going to have more herbicide bills.”
The research will include canola and wheat, and 20 different species of weeds.
At Agriculture Canada’s research centre in Lethbridge, scientists Bob Blackshaw and Henry Jansen will study how nitrogen and phosphorous influence weed growth in wheat and canola.
At Brandon, Derksen and research scientist Cindy Grant will look at the equation using potassium and sulfur.
The research should eventually offer guidance on how to target fertilizers so the crops benefit but the weeds don’t.
Timing and method of fertilizer application will be included in the studies.
“We need to rethink fertilizer management and not just assume that it only affects crops,” Derksen said.
He points to research that already has shed light on the relationship between potassium and wild oats.
A long-held belief was that producers should always replace the potassium used by their crops.
However, that approach may not be wise when growing wheat in potassium-rich soils where wild oats are a menace.
Derksen said they have found that wild oats use potassium faster than wheat.
This means applying potassium to a field rich in potassium may actually favor wild oats.
Better understanding those kinds of relationships could mean lower input costs and higher crop yields.
