Multiple species together | Polyculture crops may provide benefits, especially to organic growers
This fall, officials at the Semiarid Prairie Agricultural Research Centre in Swift Current, Sask., expect to harvest a series of unique looking plots.
They’ll be examining them and recording data as part of a three-year study into the performance of poly-culture cover crops or cocktail mixtures in southwestern Saskatchewan’s brown soil zone, in which multiple species are planted together for use as forage.
Mike Schellenberg, a range and forage plant ecologist, said the project comes at the request of producers, curious about concept after hearing about co-planted crops in the United States that showed evidence of increased organic matter, moisture retention and weed and insect control.
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Some growers in the area are already trying it, he said.
“Producers are noticing differences, but they’re unable to put the hard numbers to it because they’re not running a comparison. They’re just growing it,” he said.
In the SPARC plots, officials have planted warm season grasses (corn, sorghum and millet) along with cool season grasses (barley, triticale and oats), legumes (field peas, forage peas, hairy vetch) and root crops (purple-top turnip, forage radish and kale, all brassicas).
All of the species have been planted individually, as well as in combinations of four, eight and 12. Seeded in June, their performance will be compared to a perennial forage crop control.
“We’re not looking at actual grain yields,” said Schellenberg. “We’re looking at biomass that we can use for green feed.”
Benefits are expected as the legumes offer nitrogen fixation, while the root plants penetrate hard pan soils, providing new pathways for water to infiltrate the soil.
The closed canopy in the plots, which don’t receive any herbicide applications, offers protection against weeds, said Schellenberg. He also observed that the cocktail mixtures also didn’t receive the same insect pressure as the individually planted plots.
“We are sort of directing this to a forage end use, but the information that we’re getting off this, the organic systems are quite interested in this for improving their soil and maybe providing a non-herbicide method for weed control,” said Schellenberg.
“Even your typical producer with annual crops is interested as well for the same reasons, but (it’s) also as a crop that can break up your cycles for weed and insect issues.”
In the coming years, researchers plan to measure productivity, weed control, soil fertility and quality, while also keeping an eye on insects. Key to the project is identifying how many species are required to get the desired effect.
Schellenberg said he doesn’t expect these mixtures will substitute for alfalfa. They could, however, be used to get productivity out of land that isn’t suitable for another crop.
“In my mind, they would put this in when they have land that they’re getting ready for another use. They would put this in to get some productivity in the way of forage while improving the land in obtaining some benefits regarding weeds and insects…,” he said.
