P.E.I. research zeroes in on new kind of cover crop to help break pest and disease cycles
Researchers surprised at sorghum Sudan grass's ability to reduce barley rot issues
A tropical grass seems like an unlikely fit for Prince Edward Island, but sorghum Sudan grass is growing in popularity when it comes to preventing disease build-up by rotating other crops through the fields where cash crops like potatoes are grown.
New research from Agriculture and Agri-Food Canada shows planting the grass could also be of benefit to barley and soybean farmers.
"It's more related to corn than a lot of the other grasses that we grow in P.E.I.," said Ryan Barrett, research and agronomy specialist with the P.E.I. Potato Board. "It tends to favour hot conditions, warmer conditions than other cool-season grasses like, say, rye grass or many other grains we grow.
"It has a deeper rooting structure than some of those other grasses as well. And we've also seen in the last number of years that it can have some benefits in terms of breaking disease and pest cycles."
Barrett said farmers on P.E.I. have been growing Sudan grass for at least 10 years, in small amounts to start. The board has included it in agronomy trials for the last seven to eight years.
"Some growers were tinkering around with it. Maybe they'd seen it being grown somewhere else or they'd seen literature on it… And so they were trying it here," Barrett said.
He said the board gets involved by getting data from their fields and collaborating with Agriculture Canada on test plot experiments.
"And then we can kind of see on both sides, both plot scale and field scale, whether it's having the… intended effects."
Barrett said Sudan grass is usually planted in June, or even July, adding: "You have to kind of wait to plant it into really warm soil and then it'll take off really quickly."
Many farmers cut it repeatedly during the growing season to encourage the root system to expand as the grass regrows.
I just think it's another tool in the toolbox for some people.— Ryan Barrett
The board surveys its member producers every year about their fall cover crop plans. Extrapolating from those results, Barrett estimates the Island has 10,000 to 12,000 acres of Sudan grass or the closely related pearl millet being grown as a cover crop, either alone or in combination with other crops.
"I just think it's another tool in the toolbox for some people… For some people's rotations, it seems to work really well," Barrett said.
"There's no real slam dunk for everybody. It may fit for some rotations and not for others."
Federal research underway
On the federal side, Agriculture and Agri-Food Canada research scientist Adam Foster has also been exploring the potential of sorghum Sudan grass, as part of a larger project led by the Atlantic Grains Council, located at the Charlottetown Research and Development Centre.
"We were exploring a number of different cover crops to see what effects they would have on the soil microbiome and what carry-over effects that might have to disease on barley and soybeans," Foster said.
The researchers tested eight different cover crops by planting them in the summer a year before barley and soybean were sown in the same plots. They were sorghum Sudan grass, annual ryegrass, oilseed radish, brown mustard, alfalfa, crimson clover, buckwheat and phacelia (a member of the borage family).
Foster said researchers were surprised at how effective Sudan grass was at reducing fusarium crown and root rot in barley and soy beans.
As a scientist, the one thing I really like is discovering new things... We did not expect to see these results.— Adam Foster
"As a scientist, the one thing I really like is discovering new things, and when we went into this research, we did not expect to see these results…
"We were very surprised to see that the soil microbiome change was actually having this effect on the pathogen community. And even after you planted the crops one year, the effect carried over through the winter into the next year's crops.
"As a scientist, it's exciting and it's literally what we love most about our jobs."
Grains council spreading the word
The research is over now and results have been shared with the agricultural community, partly through an Atlantic Grains Council fact sheet.
"The Atlantic Grains Council is essential for our work," Foster said. "They represent many growers and grower organizations throughout the region, and by working with them, we can really get straight to the growers and straight to the producers without the need for essentially having lots of independent meetings.
"We're basically going to one spot to actually meet many people at once."
Grows to 2 metres tall
Potato board chair John Visser has been planting sorghum Sudan grass with millet for five years at his Victoria Potato Farm Inc.
"We were having a little bit of problem with brown mustard and so we were looking for some other cover crops that's going to help with building a healthier soil," Visser said.
"We looked into the sorghum/millet and we felt there was going to be some positive results and we grew a little bit on the small scale. Now we grow probably about 600 or 700 acres of it."
He said that with the right fertilizer, the mix will grow to about two metres in height. It grows back after being cut once during the season.
"It's supposed to give better crops in your barley and in your potatoes. Plus it grows very well in the spring when you plant it and it also helps with the weed suppression."
He said planting the sorghum/millet blend costs between $200 and $250 an acre, so they're counting on results that pay off in better yields down the road.
"Plus you do have a healthier soil. You put a lot of biomass in there."
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