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Intercropping coming closer

Research centres are building on their knowledge base through the trial-and-error approach

There are signs of both success and failure amongst the intercrop plots at Melita’s Westman Agricultural Diversification Organization.

Some look great. Others are nothing but bare soil where nothing established. In others the crops aren’t playing well together and underseeded legumes are set to overtake the crop they were supposed to support.

That’s just fine with WADO staff however. They’re as interested in finding out what didn’t work as what did. That fulfils their mandate of exploring the risks first so farmers don’t have to, said Scott Chalmers, WADO manager.

He says the nature of exploring this technique means a lot of ups and downs in the field and the value of taking on the challenge season after season.

“Certainly, these intercrops are building on previous ideas or results,” Chalmers said. “That’s kind of how science works.”

He cited the pea-canola intercrop as a good example of the many wrinkles researchers encounter. So far they’ve nailed down that when it comes to fertility, nitrogen applications won’t see a big effect but phosphorus likely will. Now they’re trying to figure out what the best practices are going to be for fungicide applications. While the crop will be denser, there might actually be less spatial risk and lower incidents of mycosphaerella because fewer pea plants will actually be touching. But that isn’t the only risk.

“On the flip side, both crops get sclerotinia,” Chalmers said.

WADO is putting fungicide applications to the test on its “peaola” this year, including plots that are intercropped with alfalfa on top of the pea-canola mix.

Westman Agricultural Diversification Organization (WADO) is adding fungicide to the equation in its “peaola” intercrop trials, field day attendees hear July 17.
photo: Alexis Stockford

Leap of faith

Intercropping is already popular in the organic sector, where producers target the method for maintaining post-harvest green cover or to address nitrogen issues by adding legumes. For many who try the method for the first time, however, the practice may still feel like a leap of faith with few standards or guidelines available.

It’s all about finding synergies, according to Dunling Wang, alternate cropping system specialist with Saskatchewan’s Ministry of Agriculture.

“There are a variety of ways to intercrop, from planting different crops to different species of the same crop or seeding two crops together at the same time or different times, seeding in a wide strip (or) inter-rows or sometimes mixing it together completely,” he said.

“The producer could think about all those kinds of crops they want to grow and then put them on the table and see how to make combinations of those and try them out,” he said.

Depending on the system, matching maturity dates may be important for a successful intercrop, Wang said, urging producers to keep harvest ability, equipment availability and grain sorting in mind.

Seeking synergies

At WADO, Chalmers is hoping to find some of those synergies between soybeans and flax. Trials from the South East Research Farm in Saskatchewan have already suggested that mixing chickpeas and flax could drop chickpea aschocyta significantly, results that inspired Chalmers to see if soybeans and flax could have a similar disease-fighting effect.

WADO seeded a double-row intercrop of the two crops this year after last year’s single-row system saw flax outcompete soybeans.

“You can kind of partition where you put the nitrogen fertilizer, which we specifically put on flax rows,” Chalmers said of this year’s attempt. “We want to get the best of both worlds. We want to grow soybeans with nodules and we want to grow flax with fertilizer.”

Crop diversification specialist Scott Chalmers details efforts to combine hemp and legumes during one of many intercrop plots at the Westman Agricultural Diversification Organization (WADO) field day July 17.
photo: Alexis Stockford

Chalmers said previous research shows nitrogen and nodules don’t mix, but says an inhibitor like Agrotain may mask that effect allowing soybeans to nodulate.

WADO collected no data from its first trials last year after deer grazed down the plots.

Wang’s advice on compatible harvest might hit a roadblock in the flax-soybean mix. Chalmers says he is concerned that the high header speed needed for flax might damage soybeans.

The pulse may also end up as a marketability barrier, he said, since buyers might be concerned about soy as an allergen contaminant.

Dealing with dry

Moisture presents another challenge, one that Manitoba farmers have become well acquainted with in the last two years, although Wang argues that intercropping itself may increase the resilience of a field.

“If you could incorporate one drought-tolerant and one wet-tolerant crop together, you could always have a crop unless it’s really, really dry and no crop would grow,” he said.

WADO’s hemp-legume experiments felt the impact of dry conditions last year.

Initiated at least partly to see if nitrogen-fixating legumes might help with residue breakdown in the high-biomass crop, WADO is currently on its second year of the trials.

“We’ve had timely rainfalls which have increased the success rate of emergence on our relays,” Chalmers said of this year’s plots. “The No. 2 difference is we’ve actually put hairy vetch in the seed row versus broadcasting it last year which was likely less successful.”

Overtaken

The centre’s hemp-hairy vetch mix details yet another quirk of intercropping, with the highly competitive legume threatening to overtake the crop it was planted to support.

Last year, vetch-planted plots showed the most biomass after hemp harvest (2,000 kg/ha compared to less than 500 hg/ha in every other legume), although Chalmers also noted that the growth threatened to cause headaches with hemp harvest, as the legume had grown tall enough to tangle in the seed heads.

Chalmers urged growers who are considering intercrops to seek advice from diversification centre staff or producers who have already grown them, as well as double-check marketing standards and insurance before hitting the field.

About the author

Reporter

Alexis Stockford is a journalist and photographer with the Manitoba Co-operator. She previously reported with the Morden Times and was news editor of  campus newspaper, The Omega, at Thompson Rivers University in Kamloops, BC. She grew up on a mixed farm near Miami, Man.

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