Production | Summer 2009
Controlled-release nitrogen a “natural” for winter wheat.
By Jennifer Barber
Different crops absorb nitrogen at different rates through the growing season. For winter wheat, which matures 10 months after seeding, controlled-release nitrogen can help meet that crop’s unique uptake pattern.
Generally, nitrogen is split-applied in fall and spring for winter wheat production. This is standard practice for several reasons, but mostly because early-fall application can result in nitrogen losses over the winter. Research has shown that controlled-release nitrogen allows application of winter wheat's full nitrogen requirement at seeding, without fear of winter and early spring loss.
Environmentally Smart Nitrogen (ESN) is a controlled-release urea product manufactured by Calgary-based Agrium. ESN has a semi-permeable polymer coating that allows water to enter the urea granule slowly, dissolving it over an extended period.
“We’ve been conducting research for years to show that ESN works well on winter wheat,” says Ray Dowbenko, senior specialist, agronomy, with Agrium. “We’ve worked with provincial groups, Agriculture and Agri-Food Canada (AAFC) and other third party groups and we’ve seen that ESN is doing good things for winter wheat.”
With controlled-release nitrogen, the nutrient becomes available as it’s required by the winter wheat plant. The release rate depends on soil temperature and moisture. Small amounts are released while the crop is dormant in the winter, but the granule remains intact and any nitrogen that is released typically stays in the ammonium form. Additional nitrogen is released in the spring when the crop starts growing again.
There also appears to be an environmental advantage to controlled-release fertilizer. “With traditional nitrogen, there is the risk of leaching or denitrification in late fall and into the spring,” says Dowbenko. “Research has shown with a controlled release of nitrogen, emissions of nitrous oxide (a greenhouse gas) could be reduced by 20-25 per cent.”
AAFC in Lethbridge, in partnership with others including Ducks Unlimited Canada, Agrium, the Canadian Wheat Board and various winter cereals groups across the prairies, has been looking into the impact of different nitrogen applications on grain quality of winter wheat.
