Research finds two crops can be better than one in forage production

By overcoming the production challenges of intercropping, cattle producers can reap the benefits of a pea-barley intercrop for forage

Rising feed costs have some livestock producers taking a closer look at a widely used, 1,000-year-old cropping practice that hasn’t yet found a foothold in Canadian agriculture.

Intercropping — the practice of growing two or more different crops together — boosts yields and improves land-use efficiency, but the real benefits can be seen in grazing operations, said Sheri Strydhorst, agronomy research scientist with Alberta Agriculture.

“What we find in temperate climates is intercropping is really most successful when it’s used for forage production compared to grain production,” she said.

In 2004 and 2005, Strydhorst looked at intercropping faba beans, lupins, and peas with barley for forage production. While lupin wasn’t competitive enough for forage, both pea and faba bean worked “relatively well,” with pea outperforming faba bean in terms of yield, she said.

“We did get higher yields with the pea-barley intercrop,” she said. “I think part of that is maybe pea is just a more competitive pulse compared to faba beans, and it’s just, in that way, a little better suited to the intercrop.”

The research found intercropping any pulse with a cereal will increase protein yield and improve forage nutritive value.

“When we had the pulse-barley intercrop, they had 40 per cent higher protein yields than a full barley crop,” Strydhorst said. “What that’s equivalent to is a quality and nutritive value similar to alfalfa at pre-bloom or early-bloom stage. Where we had barley grown alone, it was similar to having alfalfa at mid-bloom.”

Logistical challenges

Despite these benefits, Strydhorst doesn’t see many producers intercropping peas with cereals for forage, and the logistical challenges may be the reason.

“You’re growing two very different crop types together, so growers need to give a lot of thought to what their fertilizer recommendations are.”

Producers should fertilize for the pulse crop’s needs, but not for the barley crop, she said. A pre-seed burn-off with glyphosate is also recommended, but there are only a few products that can be used for in-crop weed control.

“Weed control in crop is certainly one of the concerns, but it’s not a hindrance when it’s for forage production because you can be harvesting those weed seeds before they drop and become a big problem,” said Strydhorst, who recommends seeding into a clean field.

Seeding rates

Correct seeding rates for both the pulse crop and the cereal crop are also critical.

“A lot of the intercrops done with peas and barley where things don’t work out as ideally as they could is when too high of a seeding rate is used for the barley and too low of a seeding rate is used for the pulse.”

Strydhorst’s research found seeding at a quarter-rate of barley and 1.5 times the recommended pea seeding rate worked best.

“That was equivalent of targeting 53 barley plants per square metre and about 11 pea plants per square foot,” she said. “That really gives you that good mixture at the end of the day.”

Producers can use a seed drill with multiple tanks, or if they don’t have that capacity, the peas can be seeded first at the right seeding depth, and then the barley can be cross-seeded at a shallower depth. Intercropping this way usually comes with a bigger seed bill, but Strydhorst said it balances out with reduced input costs in other areas — specifically, the reduced need for nitrogen fertilizer.

“There certainly are increased seeding costs with this because you are seeding your peas at that higher seeding rate, plus adding in the barley,” she said. “But producers have to remember that they’re not spending money on nitrogen fertilizer, so it’s not necessarily a downside.”

Producers may also see extra nitrogen in the soil and a yield boost in the year following a pulse-cereal intercrop — but not to the extent that a sole pea crop would produce.

“That cereal crop is actually using up a lot of that nitrogen.”

Considering how the two different crops will share resources is the real trick to successful intercropping, Strydhorst said.

“You’re trying to have two crops growing at the same time that are using resources at different times,” she said. “You do want very, very different species so that they make better use of the water and nutrients to improve the productivity.”

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