Canola on canola, or canola every second year: from a sustainability point, that’s scary. But given current economics of high canola prices relative to other crops, sticking to the standard, recommended practice of canola one year in four is hard to do in the short term.
“There’s no way around it. Economics is driving the tight rotations. You can’t get close with another major dryland crop to the net returns you can get with canola,” says Murray Hartman, provincial oilseed specialist with Alberta Agriculture and Rural Development.
Hartman analyzed Alberta Financial Services Corporation crop insurance records from 2001through 2009 and nailed down the trends that are easy to see driving around the Prairies. There are a lot more yellow flowers than there used to be.
“I would expect the trend to tighter rotations has continued in 2010 and 2011. We’re pushing six million acres of canola in Alberta in 2011. That’s 10 percent more than 2010,” says Hartman.
Manitoba Agriculture, Food and Rural Initiatives provincial oilseed specialist Anastasia Kubinec sees the same trends in Manitoba. She looked at crop insurance records from the Manitoba Agriculture Services Corporation from 2000 to 2010.
“I would say the trend is similar for 2011 or even tighter. I’m starting to see canola on canola stubble more frequently,” says Kubinec.
Central Alberta and Manitoba now most commonly have canola every second year. South-central Alberta has canola every second and third year most common except for summerfallow. The Peace River region has the tightest rotations, with canola on canola alternating with canola every second year most common.
In Saskatchewan, rotational records haven’t been analyzed, but given the seeded acreage of canola, the trends are likely similar.
Kubinec says canola rotations have been tightened at the expense of flax, peas, sunflowers and soybeans. Although soybeans acres are up in the higher heat unit areas, canola is less risky in shorter season areas.
“Sunflowers, peas and flax all have black eyes. It can be price or disease or maturity, but canola has looked a lot better from an economic perspective,” she says.
In Alberta, Hartman says a reduction in summerfallow and forage acres has contributed to canola acreage growth, but barley production has also suffered. In most areas, canola on wheat stubble is most common, followed by canola on barley, although the most common stubble type varies by soil zone.
Are there yield penalties?
Hartman and Kubinec also compared yield on various stubble types to see what yield penalty could be expected from growing canola more frequently in rotation. Consistently across all regions, canola on canola resulted in a 15 to 20 percent yield loss and the yield spread seems to be growing larger. In Alberta, canola in longer rotations had yields five to eight percent higher than canola in a one-in-two year rotation.
“When you look at canola every second year and only a yield loss of five to 10 percent, producers are willing to take the risk of shorter rotations for the higher revenue potential,” says Hartman. “But the data doesn’t show any risk premium for the possibility of developing a new insect or disease like clubroot that can’t be easily controlled. It shouldn’t be a surprise that clubroot started and continues to rapidly spread in central Alberta where canola rotations are so short. I encourage producers to look at the longer term as well, although I know that is difficult.”
Kubinec’s analysis found canola yields very similar between one-in-two, three and four year rotations. That makes spreading rotations out even more difficult, from an economic perspective.
“Disease is the biggest risk of short-term rotations. We are already seeing blackleg mutations overcoming variety resistance, and there is a possibility clubroot could be found in Manitoba,” says Kubinec.
While the yield penalties for shortening rotations down to one-in-two are relatively small at this point, Kubinec points out the data only covers the last 10 years, when rotations have been shortened.
“We are only into this trend for eight or 10 years. But in that time we have better varieties and herbicide-tolerant varieties with better weed control. I wonder if we shouldn’t be getting higher yields than we are,” says Kubinec.