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Ins and outs of intercropping

Intercropping researcher Lana Shaw shares tips and tricks for successful intercropping

The green crop on the left is a chickpea monocrop still flowering on August 31. On the right is intercrop that is more ripe and not flowering.

You can’t convince farmers to use long rotations if they are losing money on some of those crops, says Lana Shaw, research manager of South East Research Farm at Redvers, Sask. Nor is it good enough to only have one or two profitable crops in a region.

The industry needs to find a way to make crop diversity pay the bills, she told attendees at the AgriARM research update in Saskatoon in January. “And this is my impetus behind intercrops.”

“Intercropping is definitely a different path from what we have tried so far in the Prairies. Recently there has been a resurgence of mixed grain intercropping along with other biologically-adaptive techniques like cover crops,” said Shaw.

Sask Crop Insurance records show 34,000 intercropped acres in 2017, but Shaw estimated that farmers grew 45,000 to 50,000 of mixed grain intercrops.

“The interest is huge and it is being done in the northern Prairies.”

Who is intercropping? It’s not just organic producers. In fact, Shaw estimated the majority are conventional farmers. Intercroppers tend be younger farmers with mid-sized farms. Farmers running large operations are not usually going to have the time to deal with intercropping’s complications.

Intercropping challenges

Managing intercrops is tricky, said Shaw.

“You need both crops to be compatible with herbicides. There’s changes to seeding and harvest techniques that — depending on your equipment — may be small changes or large changes that would be required to adapt this.”

There’s also a knowledge gap, said Shaw. Intercropping is new, and hasn’t been extensively researched. Farmers can do some of trial work on their own farms. But Shaw said more research, and more research funding, is needed so that interested farmers don’t have to learn everything the hard way.

Saskatchewan is an ideal place to develop intercropping, given the range of crop types, agronomy, and processing facilities, Shaw said.

Farmers should also manage expectations with yield, as over-yielding can be inconsistent.

“If this is predicated on always having a certain percentage of over-yielding you may be disappointed, and it may be a non-starter,” said Shaw.

This intercrop is a triple crop of lentil, pea and mustard. photo: Lana Shaw

Separating grain

One of the biggest challenges is separating grain from two different crops. Shaw said farmers should consider this before seeding.

“If you can’t separate it and sell it, then that’s not good intercropping.”

That said, pulses with a limited amount of small grains mixed in can be sold with high dockage. Shaw said one farmer intercropping lentils with flax desiccated the flax and blew it out the back of the combine. The flax had been seeded at a low rate to help the lentils with standability.

Something like a dockage cleaner is another option. Shaw said it’s easier to clean a pulse with a small amount of oilseed than a 50/50 mix.

“So you can basically treat it like peas with volunteer canola in terms of cleaning and binning.”

Crop options

Asked whether there was an intercropping mix for each soil zone in Saskatchewan in a year with a “normal” amount of precipitation, Shaw had the following advice:

  • Chickpea/flax works well in the brown soil zone. Shaw thinks it will extend to parts of the dark brown soil zone.
  • Lentils with flax or mustard works in areas that reliably grow peas, said Shaw. Farmers can’t grow this mix too far north, but she said it may extend the area of adaptation of lentils.
  • Pea/canola is the best option in the north/black soil zones.

Farmers should consider crop height when looking at different crop types and varieties. If seeding canola or mustard with a pulse, that pulse needs to grow to the leaf canopy top, or close to it.

“For lentils, I want a tall, lanky lentil that lodges like mad in order to pair it with an intercrop,” said Shaw.

Shaw said crop height considerations are partly about shading. If farmers are intercropping a shorter pulse, they must lower the seeding rate of the taller crop, she added, so the short one gets enough light.

Generally, Shaw tells people to seed higher rates for pulses when intercropping. The oilseed or cereal companion crop should be seeded at a lower rate — 50 per cent of a normal seeding rate or less.

If there aren’t enough pulses, the oilseed will get ahead of the pulse. The pulse won’t fix enough nitrogen. And generally yields are better with a strong pulse stand, and an oilseed seeded as a companion. The oilseed will either get a small amount of fertilizer, or make do with what the pulses fix and what’s already in the soil, said Shaw.

Advice for specific intercrops

Shaw has experimented with a range of crop combinations. She started doing replicated chickpea/flax trials in 2013, and Agriculture and Agri-Food Canada researcher Bill May has also studied the same mix. Researchers have looked at seeding rates for both flax and chickpeas, and mixed vs. alternate rows.

Last June, Shaw had excessive moisture in one area. That excess moisture meant the chickpea mono-crop was still flowering in September, but the flax/chickpea intercrop was ahead.

“So it is changing the maturity,” said Shaw. She thinks the competition from the flax provides terminal stress to the chickpeas. This is an advantage when growing chickpeas outside of traditional areas, she noted.

So far, Shaw’s best advice on growing chickpea/flax intercrops is:

  1. Start small.
  2. Target mono-crop chickpea density when seeding.
  3. The ideal flax seeding rate seems to be 10 to 25 pounds per acre. But this is an area where farmers can do on-farm trials, said Shaw. “So vary your flax seeding rate if you’re trying this and determine what’s working under your local conditions.”
  4. Seed the chickpeas deeper than the flax. Shaw said they put chickpeas down the fertilizer shanks of their Seed Master drill.
  5. Chickpeas help thresh the flax bolls in the combine. They act like ball bearings. Sometimes you end up with flax bolls in sample, said Shaw. “It is possible to clean those out and re-thresh them (in the combine),” Shaw said.
  6. Think about intercropping as lowering risk, said Shaw. Excess rain knocked out some of their chickpeas. But the flax wasn’t flooded out. “So we had 1,500 pounds per acre of flax.” In the mono-cropped chickpeas “we had a big weed patch,” said Shaw. Farmers could see benefits across a landscape that wouldn’t be seen under ideal plot conditions.

Mustard is also a nice intercrop, said Shaw. Yellow mustard doesn’t shatter, and has a relatively low seed cost, making it a good pair to many pulse crops.

A mustard-lentil intercrop has a few purposes, Shaw said, including:

  1. Reduce lodging and improve harvest standability;
  2. Possibly reduce disease pressure;
  3. Possibly over-yield; and,
  4. Better weed competition.

In Shaw’s trials, yellow mustard grown with large green lentils didn’t lodge, even when the mono-cropped large greens lodged. Last year, their intercropped green lentils ended up yielding 95 per cent of the mono-cropped lentils. They also got 300 pounds per acre of “bonus mustard” from the intercrop.

Shaw sees more potential for uptake on intercropping in 2018, as crops such as maple peas and mustard are worth more money.

Interested farmers should search “intercropping” on Twitter, Shaw said, as researchers and farmers are talking shop online. And she added that farmers can start small.

“This isn’t like organic farming where you’re all in or all out.”

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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