A 50-year study confirms that farmers can safely remove straw from their fields as long as they don’t take too much.
The Agriculture Canada study measured the proportion of total above ground residues removed through baling and evaluated the long-term effect of straw removal on soil quality and wheat production.
Guy Lafond, a research scientist at the department’s research farm near Indian Head, Sask., said the project included two separate studies, which were published in the American Society of Agronomy’s Agronomy Journal in 2009.
Read Also
Stock dogs show off herding skills at Ag in Motion
Stock dogs draw a crowd at Ag in Motion. Border collies and other herding breeds are well known for the work they do on the farm.
“In addition to the 50-year study, we also wanted to measure how much straw we really did remove in baling,” Lafond said.
“Using conventional baling and harvesting techniques, you really don’t remove nearly as much as you might think of the above-ground material other than grain.”
The long-term study used a three-year rotation of fallow, spring wheat and spring wheat.
There were three treatments:
• no fertilizer applied and no residue removed;
• fertilized with nitrogen and phosphorus and no residue removed;
• fertilized with nitrogen and phosphorus and residue baled and removed every cropping year.
The percentage of total above ground material, other than the grain that was removed, was either 22 to 35 percent or 26 to 40 percent, depending on the method of calculation.
“At such low volumes two out of three years, there was little or no impact after 50 years,” Lafond said.
“Measurements of soil organic carbon and nitrogen showed no differences after 50 years of straw removal. Spring wheat yields and grain protein concentration were also not affected.”
The paper said the potential exists to use crop residues for industrial purposes without adversely affecting the long-term productivity of medium to heavy textured soils based on removal of less than 40 percent of the residue only two years out of three.
“So I can remove some straw without a negative impact, but not every year and not right down to the ground.”
Lafond said it’s a different story if farmers use a chaff wagon, ensile the crop, bale right out the back of the combine or use something like a McLeod Harvester.
“That may remove too much residue to be sustainable. If you did total removal like that, I’d think that one year in four makes sense.
“A side benefit of any baling is you have easier seeding the next year. Strategically, you’d want to bale a cereal field the year before you plant canola on that land.”
