SASKATOON — Polycrops, intercrops, cover crops and cocktail crops are different terms that all encompass planting mixed crop species for livestock feed.
Proponents of polycrops have found that mixing different plant species when growing crops can help improve soils by adding more root systems, microbiological communities and organic matter. Compared to single-species crops, polycrops may also show resilience against pests and disease. While benefits are well-publicized, as with any farming practice, trying something new requires a realistic approach.
One Saskatchewan Farm’s Experience with Polycrops in Production
Jocelyn Velestuk operates a multi-generational family farm with her husband, two children and her in-laws. The mixed grain and commercial cow-calf operation in southeast Saskatchewan has used polycrops for a few years, with the primary goal of improving their soils.
Jocelyn, who has a background in soil science research, was excited to include polycrops in their rotations. “We had to figure out how to get our land to be more productive, so I started learning about intercrops and polycrops,” she says. “When we were first deciding whether we wanted to jump into them with both feet, we had many conversations,” she adds. Jocelyn admits she was somewhat skeptical because there wasn’t a lot of science backing some of the polycrop claims.
They had an opportunity to try polycrops when they rented a new field that needed some improvements. “There had been heavy tilling,” she describes. “It was definitely hurting, that spongey organic matter was missing,” she says. “Nutrients were non-existent, there was a very low nutrient supply in our soil, so knowing all this, my husband and I asked, how are we going to be profitable?”
They decided the lowest-risk way they could incorporate polycrops was with an annual blend they would make into silage bales.
“I can put whatever in there as long as we get the material,” Jocelyn reasons. “I wanted to make sure we were adding root systems,” she says. “My goals were centred on getting that rhizosphere and getting that soil working again.
“We did try some kale and clovers and did a mix of cereals with oats and barley together, and it didn’t turn out really great,” she admits, adding that flea beetles knocked out the kale which was supposed to make up the bulk of the material. It did still make decent feed despite not being as productive as they had hoped.
The rhizosphere is the immediate zone including and between plant roots and soil. Sometimes it is called the “root-soil interface” and is the area that is influenced by roots, root secretions and soil microbes.
The following year, they decided to simplify the mix more. “We kept with red clover, oats and barley which made great feed with huge production,” she says. She also added that in doing so, they found less rust in the cereals compared to when they were grown as monocultures.
Despite having some past successes with polycrops, this year the Velestuks simplified their cropping decisions even more and decided to stick with straight barley. “With the price of barley being so high and not knowing how your crop is going to be if we have enough silage and greenfeed then we can combine the rest,” Jocelyn explains.
Using Research to Learn More About Polycrop Popularity
Dr. Bart Lardner with the University of Saskatchewan says his team has been looking at polycrops since they started gaining popularity around five or ten years ago.
The principle behind polycrops is to keep the land covered for longer throughout the growing season and into the dormant season, he says. “Along came the different new mixtures, species and blends, with some that may or may not have been adapted to western Canada,” Lardner adds.
“You can get pretty well anything you can dream up in that mixture, and you’ll see mixtures from three species to 27 species,” Lardner says. “I always challenge producers if you buy the complex versus simple mixtures, are you sure that species 17 or 23 gave you anything for biomass? If you’re paying for it, you want to make sure it works,” Lardner says.
“Based on our experiences there are a lot of claims [about polycrops], but as a research community, we should look at those and validate and be truthful about what’s happening.”
Through collaboration between the Livestock and Forage Centre of Excellence and Agriculture and Agri-Food Canada, Lardner and his team are assessing polycrop mixes at two different Saskatchewan sites for yield, biomass and quality. The research compares three treatments of a single oat monoculture; a simple four-species mix of oats, pea, brassica and hairy vetch; and a complex mix with eight species, adding red proso millet, teff grass, chicory and barley to the four-species mix.
After looking at the results, Lardner found that yields were quite comparable among all three treatments of oat, four-species and eight-species mix, coming in at around two tonnes of dry matter/acre during some very dry conditions. “We also saw pretty good crude protein, 13 to 14% and lower [neutral detergent fibre] of around 46 to 48%,” he explains.
Science is showing that polycrops have promise below ground as well. “The good thing is the different rooting systems, the fibrous versus taproots,” he says. “We’re seeing more root biomass with these polys than monocultures,” he says, adding that in the short term, they’ve noticed in areas that previously had low soil organic carbon, the polycrops have increased those levels.
This continuing study will assess data to determine whether the different mixes yielded different greenhouse gas emissions from animals during grazing. Scientists will also continue to look at soil organic carbon changes over time.
Twelve Tips for Using Polycrop Mixes
1. Start with simple mixes. “Maybe think twice about buying the 20 species mix,” says Lardner. “Go simple so you’re sure when you seed them you can see evidence that they are contributing to yield.” Velestuk agrees and says they try to use plants that they know are already adapted to their area.
2. Start on a smaller scale. “Don’t go crazy and seed a whole quarter, maybe start with 10 or 20 acres, see how that blend works depending on where you’re at, and see how they’ll yield,” says Lardner.
3. Aim for success. Jocelyn performs soil tests and chooses a customized fertilizer blend to meet their specific needs. “We fertilized pretty good, we don’t cheap out, that has to feed our cows,” she says.
4. Feed test. Lardner advises producers to feed test before grazing or feeding polycrops. Farmers should be aware that if they plan to use polycrops for fall or winter grazing, depending on the class of animal, they may need to supplement their herd for energy which can negate any savings.
5. Be mindful of the percentage of species type in the mix and how that can impact forage quality. For example, Dr. Lardner has experience suggesting you don’t want more than 20% of brassicas in the mix. “With too many in there, you can see issues in elevated levels sulfur, nitrates, elevated levels of potassium which is antagonistic with magnesium,” he explains.
6. Consider pre- and post-polycrop weed control. “With a polycrop, you can’t spray in-crop, so if you have noxious weeds, or those ones that want to linger, it might take more herbicides, later on, to help you gain control,” Jocelyn explains. “We’ve always had challenges with weed pressure, and some can have anti-quality factors,” Lardner agrees.
7. Use what you have. For mixing and seeding polycrops, the Velestuks opt to use equipment already on hand. “For mixing seed species, we use a mix mill, and we seed it all with our air drill,” explains Jocelyn.
8. Strike a balance with seed depth when seeding multiple species. Jocelyn says with their polycrops, they seed everything relatively shallow but still at a depth of around three-quarters of an inch. “It needs to be into moisture,” she recommends.
9. Avoid grazing fields before freeze-up. One season, Velestuks included winter triticale in their greenfeed mix with the idea that the triticale would be a post-silage cover crop. “Once we took the silage off, the triticale did come up and we grazed the stuff that was fenced, but those hooves on stubble really pack the soil down,” she cautions.
10. Be aware that polycrops may require special business risk management. Jocelyn notes that ag risk management programs may not support polycrops as easily as single-species commodity crops. Farmers need to determine whether polycrop benefits outweigh the risk of growing a crop that potentially cannot be insured.
11. Keep an open mind on the end-use of polycrops. “Producers may use the crop for silage, or for green manure, that’s an opportunity,” Lardner says. Polycrops can also be used for grazing as a standing crop or for baled feed.
12. Remember perennial forage blends are polycrops, too. Some of the greatest successes on the Velestuk farm have been incorporating perennial forage mixes into shorter-term rotations. They’ve used oats under seeded to yellow blossom sweet clover, sanfoin, bromes, slender wheatgrass and timothy. “The goal was short-term forages, meant to be in for three to five years, but when it’s producing so well, it’s hard to take it out of production. It’s year six, and it’s looking really good still.”
The benefits that polycrops provide may make them suitable for many farms in the short- or even long-term. However, there are a lot of variables that go into cropping decisions. “It really depends on a lot – what our financials are looking like, what our business priorities or challenges are that year, what the markets are doing, what world stuff is going on,” says Jocelyn Velestuk. “Science can sometimes be dealing with averages, but there is no prescription for farming and everyone must adapt the science to their own farm circumstances,” she concludes.
