Intercropping lowers use of chemicals

Lana Shaw shows participants an intercrop trial at the field day. Intercrops generally use less chemicals. |  Photo by Melissa Bezan

Southeast Research Farm manager says farmers can often reduce nitrogen fertilizer if legumes are included in the mix

Intercropping is an important part of the research carried out at the South East Research Farm in Redvers, Sask.

Intercropping often leads to a decrease in the amount of chemicals needed, which can have many positive impacts.

“If you can grow some peas together and get a good pea crop and kind of a bonus oat crop with very little nitrogen applied, that checks some good boxes for environmental reasons and economic reasons and profitability reasons if it means that you’re not using as much pesticides on some of these combinations, which tends to be what happens,” said Lana Shaw, the research manager at the South East Research Farm.

Shaw said farmers should start with a clean field if they plan to intercrop because there are fewer registered herbicides available that can be sprayed on two crops.

“As far as fungicides go, it’s part of some ongoing trials trying to figure out why there seems to be less disease in some crop combinations. But in literature it’s very common to see reductions in disease that it might be partly due to the spread of the disease being interrupted by having a non-host there.”

“When it comes to insects, our pest insects are very well adapted to monoculture situations…. (Intercrop) mixtures are a bit less suitable as breeding grounds for insects or they’re less attractive for them. Even if you have the same amount of bugs in there, it still may change the economic threshold for doing control measures on those insects because there’s usually a crop in there that will compensate for damage.”

As well, farmers can often reduce nitrogen fertilizer because usually a legume is included in the intercropping mix, which boosts soil nitrogen.

According to Shaw and the southeast research farm, the chickpea-flax intercrop is most reliable for needing less fungicide.

“Michelle Hubbard did surveys on producers’ fields,” she said. “And they were finding the same thing. Farmers were spraying less fungicide on their intercrops and they had less disease.”

Shaw said although it hasn’t been proven, the data leans toward intercrops needing less fungicides.

Scott Chalmers, a diversification specialist with the Westman Agriculture Diversification Organization, said intercrops succeed where monocrops often fail.

“With monocrops, they fail because maybe their populations are too close together, so the plants are touching each other,” Chalmers said. “That’s not normal in nature for things to happen that way, and so therefore disease may prevail in those conditions.”

Chalmers said some intercrops would need no chemicals at all.

“By utilizing some of the intercropping benefits, there will be no need in some examples to use chemicals which would have traditionally been used in their monocrop predecessors,” he said.

However, Chalmers said it’s hard to say on whether intercropping will become common practice.

“Sometimes market prices, especially at this point in time, can really dictate what producers do. Right now, maybe a lot of producers don’t feel comfortable taking the risk of intercropping when prices are almost double what they were two years ago.”

Another consideration is the environmental conditions.

“During drought conditions like we have right now, growing peas and canola together is probably less wise because intercrops, in some cases, require more water.”

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