Study to improve nutrient management practices

Snow melt runoff | Frigid winter conditions on Prairies may require changes to grazing, fertilizing and seeding methods

Barbara Cade-Menun will be heading out into the field in the coming weeks. 


As she has since 2010, Cade-Menun and other Agriculture Canada re-searchers will be collecting snow melt runoff and studying its nutrient composition as part of an ongoing project to assess existing management practices for nutrient loss.


“Yes, we’re concerned about the environmental impacts, but we also are trying to make sure that nutrients stay where they are needed,” said Cade-Menun of the Semiarid Prairie Agricultural Research Centre. “We don’t want to fertilize the lakes. We want to fertilize the fields.”


Preliminary results of her work in southeastern Saskatchewan were published last year in the Canadian Journal of Soil Science.


Those numbers found nitrogen and phosphorus concentrations in runoff from crop and pastureland exceeding water quality guidelines. 


Cade-Menun said the project supports the development of nutrient specific best management practices tailored to specific regions. 


The project was originally funded through Agriculture Canada’s now concluded Watershed Evaluation of Beneficial Management Practices initiative, but will continue through 2016 with new funding.


“A lot of the best management practices that have been developed in the U.S., for example, or in Ontario or in Quebec, are in places where they get far more summer storm runoff than we get,” she said.


In those areas, producers will be looking to minimize losses due to erosion from rainfall, but on the Prairies, snow melt runoff is the major contributor to lost nutrients such as nitrogen, potassium, carbon and phosphorus. 


On frozen soil, snowmelt runoff that contains nutrients in dissolved form is carried further than runoff caused by rainfall. 


Other factors to consider include the region’s semi-arid climate, zero-till practices on cropland and in-field winter bale grazing on pastureland.


“The study has raised all the different things that we need to test now,” said Cade-Menun, including the timing of spraying, when to spread manure and if farmers should be 
tilling. 


“These are things we need to question. Should we be putting our nutrients further down in the soil, especially phosphorus?” she said.


“If going to zero till, if it is causing this buildup in the top inch, half inch, is that anywhere near where the crop actually needs it during the growing season? Should we be looking at practices where we’re moving things further into the soil?”


Cade-Menun said ranchers who bale graze in the winter need to be mindful of how water moves on their pasture so that they can retain nutrients and keep them out of wells. 


She said she’s also seeing evidence that fecal bacteria such as E. coli can overwinter.


“We didn’t realize that these things could survive the winter as well as they do,” she said.


“Snow is a wonderful insulator, so when the cow patties are put down and the snow goes over top, things live pretty happily in there.”


She said a lack of water quality issues downstream indicates bacteria probably don’t survive long after leaving the field.


“There is a lot of interest of course in E. coli throughout the world, but it’s studied in warm climates. People have always been more interested in the heat effects. Nobody has ever looked at cold.”

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