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Cover Crops May Fight Weeds, Fix Nitrogen In Manitoba

Organic farmers are long-time users of cover crops to control weeds and add fertility, but a University of Manitoba researcher says they may be an option for conventional farmers as well.

There are multiple benefits from using plants to manage soils and so I m hoping that my research here will explore what the benefits are and also get creative in thinking about how to work them into our short growing season, said associate professor Yvonne Lawley.

She said cover crop use was more common prior to the green revolution, but added farming practices at that time also included more fallow.

Cover crops are more of an older practice that I think we re coming back to, said Lawley. When we began to have the wide-scale adoption of fertilizer, and increasing options for herbicides, we didn t need to rely on plants to manage soils.

But that change is beginning to come full circle with farmers in some areas again looking to plant-based management practices to preserve and improve soil quality, fix nitrogen and build nutrients.

Some of the challenges or limitations we have with our current cropping systems can be addresses by introducing cover crops to different degrees of effectiveness, she said.

Lawley is currently working to determine what types of cover crops could work in Manitoba, and has research plots in Portage la Prairie, Winkler and Carman.

Before joining the University of Manitoba in January, Lawley completed her PhD at the University of Maryland where she took part in a large multidisciplinary study of cover crops, focusing on radishes.

She said that in warm soils, radishes they are vigorous enough to emerge quickly and suppress weeds. The large tap roots are also good at fighting soil compaction, which was a chronic problem for farmers in the Maryland area where Lawley s research began.

Now I m looking at them again and wondering if this really is the best cover crop for Manitoba, she said. We could have other issues here, other diseases, other pressures that may either compromise the health of the radishes or the canola& we just don t know yet.

This year Lawley has explored the affect of cover crops on corn, soybeans and wheat, by broadcasting and drilling seeds into the crops at various times throughout the season, including in the early stages, the harvest period, and even following harvest in the case of wheat.

There were challenges this year with the very wet weather and then the very dry conditions, Lawley pointed out. The seeds I broadcast this year didn t have enough moisture to germinate& so it really depends on when you get your precipitation.

In addition to radishes, Lawley used turnip, clover and other small seed crops to study the impact. She noted in North Dakota, where she had been a research agronomist with The University of North Dakota, cocktail seed mixes were commonly used.

The researcher took advantage of wet conditions at her Portage la Prairie test site by studying the affect of cover crops in reducing the impact of excess moisture.

Although too early for definitive results, Lawley and her colleagues will continue to pursue the potential of cover crops in Manitoba.

It s not just about yield, it s about the whole cropping system, which is what

I m hoping to build my research around here in Manitoba, she said. shannon. [email protected]

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It snotjustaboutyield,it sabout thewholecroppingsystem.

YVONNE LAWLEY

About the author

Reporter

Shannon VanRaes is a journalist and photojournalist at the Manitoba Co-operator. She also writes a weekly urban affairs column for Metro Winnipeg, and has previously reported for the Winnipeg Sun, Outwords Magazine and the Portage Daily Graphic.

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