Cover crop shown to deliver nitrogen, yields

Ontario field trials looked at corn and 
wheat yields using hairy vetch and clover

HARROW, Ont. — As Ontario farmers start to explore the potential of cover crops, an Agriculture Canada researcher is putting numbers to the potential benefits.

Xueming Yang spoke at an open house at the Harrow Research and Development Centre Sept. 10.

“We started this because we were looking at an alternative to manure for organic farmers, especially in places where it’s not easy to access,” he said.

Yang is also examining the potential for cover crops in conventional systems at a nearby heavy clay-loam location, but the organic plots on the sandy loam soil at Harrow are generating the most interesting results.

These plots, together with a conventional check, are under corn-soybean-wheat rotation. One trial, conducted over the past three years, involves a comparison of three cover crops established after winter wheat.

Yang feels he’s found a winner. The greatest yield impact on the following year’s corn has so far come from hairy vetch, which was spring plowed before planting corn.

The conventionally produced corn grown with commercial fertilizer achieved the highest yields in 2014 and 2015 at 225 and 213 bushels per acre, respectively — and a similar scenario appears likely to play out this year.

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The organic corn planted after hairy vetch yielded considerably less, but Yang is excited by the results. About 180 bu. per acre were harvested in 2014-15 and he expects a similar yield later this fall for 2015-16.

The organic corn grown without the benefit of a cover crop has consistently yielded around 100 bu.

Yang also tried crimson clover and red clover. Both improved the following year’s corn yield, but not as well as the hairy vetch.

Yang used 134 pounds of nitrogen fertilizer per acre in the conventional plot. The three cover crops were credited with producing anywhere from 70 to 110 lb. of nitrogen, with the hairy vetch delivering higher amounts on a more consistent basis.

The conventional cover crop trial been more of a challenge, likely because it’s been carried out in heavy clay-loam soil under no-till management.

That necessitated a burndown of the cover crops rather than working them into the soil.

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Yang plans to break with no-till and fall plow clay-loam plots and try both spring and fall strip-tillage.

Yang has also had success interseeding cover crops into standing corn around the six-leaf stage this year. It’s a relatively new practice in Ontario.

“On the U.S. side, they’re really pushing hard to interseed their corn. In my mind, I think Canada is behind in this.”

The interseeded hairy vetch in standing corn appeared to have the greatest amount of top growth, followed by crimson clover.

The sebania, a type of pea, failed to thrive.

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