Intercropping boosts production and shaves input costs
Growing diverse crops has long been the hallmark of Greg Busch’s no-till operation near Columbus, North Dakota. It’s not uncommon for Busch to grow as many as eight to 10 cash crops in one season, with cover crops on some acres.
The benefits of growing multiple crops are many. “Having a diverse rotation helps me reduce my nitrogen costs; it reduces disease, and broadens marketing opportunities,” he says. “It also helps me improve soil biology, and it lengthens the time that I have living roots in the soil.”
In recent years, Busch has taken crop diversity a step further by growing two crops together in one field. “I’ve tried growing chickpeas and flax together, but I’ve had the best luck growing field peas and canola as companion crops.”
Pairing field peas and canola in the same field has worked well, too, in research trials at the North Dakota State University Carrington Research Extension Center (CREC). Companion crops also showing the most promise of several combinations are flax-lentil and chickpea-flax.
“Potential benefits of intercropping include an increase in total crop production, stabilized production, improved water and fertilizer-use efficiency, reduced incidence of pests, full use of the frost-free season, enhanced soil biological activity, reduction in erosion, and improved crop harvestability,” says Blaine Schatz, CREC director.
A Balancing Act
Achieving increased production from intercropping is a balancing act. The CREC research indicates that planting both crops at reduced rates is key to getting overall increased production from the field. Each crop yields less than a full stand of either crop, but together, the two crops yield more than a single-species crop of either.
“In some of our recent work looking at intercropping field peas and canola, we’ve planted the canola at 33% of the normal seeding rate for canola and 66% of the normal seeding rate for peas,” says Schatz. “The companion crops had a 15% to 30% increase in total production over either crop by itself.”
Busch, too, has seen competitive yields from an intercropped stand of maple field peas and canola. But, more importantly, he says, intercropping peas and canola on his farm increases per-acre net profit by reducing costs for seed, herbicide, and nitrogen (N).
The first step to realizing those benefits is choosing companion crops that mature at the same time, permitting both crops to be harvested at once. “When considering which crops to choose as companion crops, it’s important to look for crops that have synchrony in development and time of harvest,” says Schatz.
Busch originally considered growing yellow peas with canola, but found they matured too early, making the pea crop potentially prone to shattering by the time the canola was ready to harvest.
“Maple peas mature later than yellow peas,” says Busch. “But they’re a vining type of pea that grows really tall. A solid stand of maple peas will go flat to the ground once they mature. Then they’re prone to molding. But the canola acts as a trellis for the peas, keeping them off the ground.
“In my experience, a side benefit of growing peas with canola is that the canola seems to alleviate root rot in a field,” says Busch. “Last year I didn’t have a problem with root rot in an intercropped stand of maple peas and canola, even though I had a straight stand of yellow peas adjacent to that field that had a problem with root rot.”
Busch seeds the maple peas at 85 pounds per acre, or about two thirds to three fourths his normal seeding rate. He seeds the canola at 2 pounds per acre or about one half his normal seeding rate.
He’s had success intercropping the peas with a non-GMO variety of canola, thus reducing seed costs. “I’m shaving as much as $12 an acre off my seed costs by not growing a herbicide-tolerant variety of canola,” he says.
Intercropping also reduces herbicide costs.
“Because I’m just using a grass herbicide on the peaola, my herbicide costs are considerably less than if I was applying a broadleaf herbicide to straight canola, which would cost me about $15 an acre,” says Busch. “I probably only spend about $3.50 per acre for the grass herbicide.”
Savings in nitrogen costs result as well from the pea-and-canola intercrop. “Even though canola is a high user of nutrients, I haven’t been adding nitrogen to the peaola, other than a little ammonium sulfate,” he says. “I’m thinking that the nitrogen-fixing of the pea is providing enough fertility. Because of that, I’m saving $65 to $70 an acre in nitrogen costs.”
The cost of separating the seed after harvest is indeed an additional cost of intercropping. “I hire a neighbor with a sieve mill to separate the peas from the canola after harvest,” says Busch. “It amounts to an expense of $25 an acre.”
While maple peas and canola have proved to be good companion crops on Busch’s farm, chickpeas and flax have not worked as well.
“I had success growing chickpeas and flax together on a small acreage in 2018, and so I increased my acres in 2019, but I had a wreck,” says Busch. “Weeds were a problem, and I wasn’t able to do much with a broadleaf herbicide. I also had mold in the chickpeas. I ended up using a stripper header to harvest the flax by itself.”
He hopes to find better crop synergy by pairing flax with lentils. “That crop combination offers potentially less financial reward but also less risk,” says Busch. “I think flax and lentils could be stable companions.
“Intercropping seems to be enhancing soil health on my farm,” he adds. “The soil is mellow, and I grew a bumper crop of sunflowers following companion crops. Besides that, intercropping helps me shave my input costs, and that’s just like money in the bank.”