Latest articles

Doing the math on intercropping

Rocket science starts to look easy when farmers delve into the complexity of this system

On the surface intercropping is a simple idea — grow two crops together in one field and take advantage of the synergies that result.

Proponents say it helps build the farm’s bottom line and soil health while lowering dependence on expensive inputs.

But underneath that simple idea is an array of complicated decisions and compounding variables. Add into it a lack of research into the topic and it’s a challenging question for farmers pondering taking the plunge.

Why it matters: Intercropping can help farmers make more with less, but getting their heads around the complexity of the system is going to be a big challenge.

Nick Cowan, who manages 10,000 acres of cropland near Hartney, finds cover crops manage weeds; he hasn’t used a fungicide in the past four years and he’s now only applying the occasional emergency pesticide pass. He likes the results, but admits it’s no small challenge.

“It’s definitely tricky,” Cowan said at an intercropping workshop in Brandon Nov. 14.

Intensifying

The lure of intercrops can be boiled down to doing more with less.

Two or more crops are planted together in the same field, and they benefit and support each other. They take advantage of spatial variability and occupy different parts of the field profile. The diversity makes the mix more robust than a monoculture and therefore less susceptible to diseases and pests.

When this is all added up the results are less inputs and a benefit known as ‘overyielding’ where the intercropped crops outperform monocultures.

Some proponents are intensifying on a smaller footprint, bucking the trend to ever-larger farms.

Producers discuss their own successes and challenges with bringing intercrops into their regular rotation during an intercropping workshop in Brandon Nov. 14.
photo: Alexis Stockford

Joe Wecker farms on the Regina Plains of southeastern Saskatchewan and he says his operation has dropped from 11,000 acres to 9,000 acres in recent years. They consciously sold their most distant land, pulling back into a smaller but easier-to-manage footprint. He told conference attendees the operation found the additional land was “no longer necessary.”

Lana Shaw, a researcher who’s worked with intercrops at the South Eastern Research Farm near Redvers, Sask., says she’s also noted the trend of intercropping producers consciously shrinking their farm acreage as they find the full benefits of the system.

Complex

Even the most passionate advocate of the practice will concede one thing about intercropping — it adds a healthy dose of complexity to farm planning and in particular to rotations.

With more crops in play it’s even more important to keep Mother Nature off balance with crop rotation, said Scott Chalmers of the Westman Agriculture Diversification Organization (WADO).

“Don’t be predictable,” he advised, stressing biodiversity in the rotation.

It’s something that Shaw has also stressed, saying a tight intercropped rotation is still a tight rotation.

“Whatever crops you’re going to grow, we still need to be aware of spacing out those crops,” she said.

Shaw suggested rotating different types of pulses, cereals and oilseeds within the intercropped rotations to help minimize resistance pressure.

“If you have pulse and oilseed intercrops every two years, pick an entirely different pulse and oilseed two years from now,” she said.

The same principle will help a producer avoid overusing certain herbicides, she added.

Chemistry will also be more complicated with an intercrop. Farmers must find an effective herbicide mix for all crops in a field. There can be concerns about herbicide residues in some of the crops and there are regulatory hurdles as some products may not be registered for certain companion crops.

Ongoing preoccupation

Intercropping farmers agree they spend a lot of time thinking about and adjusting their rotation.

At times decisions can come on the fly and incorporate observations from the field such as weed pressure.

Andrew Harris, who operates an organic operation near Stonewall, said during a producer panel at the event that the farm has no ‘set-in-stone’ rotation, but instead focuses on always maintaining a green cover during the growing season and adding enough biomass to choke out weeds and improve soil.

Cowan cut back on canola, something they usually grew every two to three years, after noting that his farm was continually spraying fungicide and insecticide.

“Our farm philosophy would be, let’s produce what the environment’s telling us to produce, not what the market’s telling us to produce, because markets change,” he said.

Livestock can also help with that process, Cowan said, noting he turns his 600 head out on crop residue regularly.

Harvest challenges

Likewise, getting the crop off is more complicated, and Cowan says their farm is usually one of the first combining and the last to finish.

Seed separation adds another wrinkle to the work flow in any given year, although Shaw argues that might be less concerning if researchers get a better handle on storage, so seed can be sorted at the farmer’s convenience.

It’s not enough to choose crops based on the already more complicated agronomy. Instead, producers must choose their mix based on both maturity dates and easy separation to ease harvest.

Nick Boundy, who farms near Boissevain and also draws business cleaning grain, suggests farmers focus on seed size rather than relying on equipment like colour sorters. Some intercrops, such as peas and cereals, may be too close in colour, he said, while other crops may have enough variation in colour to make a colour sorter problematic.

“The bigger the seed difference, the easier it is to separate,” he said.

At the same time, farmers may get an unpleasant surprise if a large grain, like a pulse, turns out small while its companion cereal crop turns out large.

“You need a margin of error there,” Shaw said.


Pros and cons of intercropping

Farmers who love intercropping say it’s given their farms many benefits such as:

  • Greater profitability;
  • Lower input costs;
  • Higher soil organic matter; and • Less weed pressure.

They also say there are more than a few challenges and complexities to master including:

  • Rotational complexity;
  • Harvest challenges;
  • A steep learning curve; and
  • Herbicide selection challenges.

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.

explore

Stories from our other publications

Comments