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Using ecological systems

Diversified, long-term crop rotations can pay off for Prairie farmers with strong management skills who are prepared to invest the time to carry them out


Updated Sept. 19, 2014 – Canadian farmers have good management skills, but those skills aren’t being rewarded in the conventional system, says a Manitoba researcher.

“On well-managed organic farms, or ecological farms, I’ve seen farmers really being rewarded for their management skills,” says Dr. Martin Entz of the University of Manitoba.

Entz says there is some middle ground between conventional and organic production. The most useful thing farmers can do is rethink and diversify crop rotations, he says.

Rotations that are five or six years long don’t have a lot of problems, Entz says. “And so many of the problems our farmers are facing are really a function of the monoculture system that we’ve been drawn to.”

Farmers looking to loosen up rotations should look for crops that don’t host many pests and that offer different weed control strategies, he says.

The conventional rotations at the University of Manitoba’s Glenlea research station illustrate the benefits of diverse rotations. The grain-only conventional rotation looks “absolutely gorgeous,” says Entz, but has “a big patch of herbicide-resistant wild oat in the middle of the plot.”

“Over the 23 years we’ve done this rotation we’ve selected for herbicide-resistant wild oats,” says Entz. He adds they have Roundup Ready soybeans in the rotation that clean up the wild oats for a year. But the persistent weeds returned.

The other conventional rotation, which has a short-term alfalfa phase, has “no wild oats. No hint of resistant weeds,” says Entz.

Another rotation consideration is whether a crop, such as a legume, can save money through the whole rotation, says Entz. “That’s huge because nitrogen costs are huge.”

The alfalfa phase in Glenlea’s conventional grain rotation cut the rotation’s fertilizer needs by 40 per cent and left soils in better shape than the grain-only rotation.

A 12-year study by Agriculture and Agri-Food Canada looked at nine different cropping systems at Scott, Saskatchewan. Researchers found evidence that using perennial forages in rotations, along with reduced tillage, improves soil quality and the soil’s ability to supply nutrients.

Reduced tillage, especially when combined with a diverse annual grain cropping system, was also linked to better soil structure in the Scott study. And researchers found more mites, which are an indicator of soil health, in systems that combined fewer inputs and reduced tillage, than either the high input or organic systems. Nearby native prairie had more mites than any of the farming systems.

The Scott study also looked at the economics, energy use, and agronomic aspects of the cropping systems. You can read the results of the Scott study online.

How much microbial biomass carbon, or living organic matter, is in the soil depends on management. Entz says a well-managed organic system results in just as much carbon in the soil’s surface layer as conventional systems, with more of that carbon being alive in the organic system. For example, the organic forage-grain rotations at Glenlea contained more living organic matter than their conventional counterparts. Conventional grain-only rotations had more living organic matter than the grain-only organic rotations.

Glenlea researchers also found out the hard way that their organic grain rotation needs a green manure every third year, instead of every fourth, to maintain nitrogen levels in the soil.

They also found including alfalfa in the organic grain-forage rotation doesn’t provide enough soil phosphate long-term. But adding composted cattle manure restored the rotation.

Diversification can extend beyond crops. Although many farms are trending towards specializing in grains or livestock, Entz points out mixed farms are still popular in many regions “and really doing a fantastic job of managing their problems. So much of the Parkland region is mixed farms.”

Better advice

Entz also says farmers should get better advice.

“I have a lot of faith in the agronomists that we have working in the industry in Western Canada but I think that they need to offer farmers a true sort of ecological package in addition to their conventional package of information,” he says. “And that’s why we had the advanced organic diagnostics school here to train those agronomists in those things.”

Farmers should also track the types of extension events they take in “because so many of them are talking about the same thing, like a new herbicide or a new variety,” says Entz.

“And what farmers should do is look for opportunities to go to field days and events where people talk about changing your rotation.”

Entz says he thinks most farmers know their system could be improved. He says they should be asking for more innovation from governments and universities.

“And that’s what we pride ourselves (on) is having something that’s a bit radical, a bit diverse, but it really shows farmers what is possible outside the paradigm they’re in right now.”

For more information, contact Entz by email or visit the University of Manitoba website for Natural Systems Agriculture.

About the author

Field Editor

Lisa Guenther

Lisa Guenther is field editor for Grainews based at Livelong, Sask. You can follow her on Twitter @LtoG.

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