Researchers think they might have a fix for farmers facing the triple threat of drought, sal-inity and high fertilizer prices.
It is called AC Greenfix and it is a chickling vetch, a green manure pulse crop that fixes nitrogen.
Harold Steppuhn and Bix Biederbeck, scientists at the Agriculture Canada research centre in Swift Current, Sask., are suggesting a green manure, also called green fallow, might be a good fit for some farmers facing multiple problems this spring.
Steppuhn said they looked into the issue after hearing from farmers in dry southern Alberta and southwestern Saskatchewan who were worried about farming dry but salt-affected fields.
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“That led us to think about the possibility of a summerfallow substitute,” Steppuhn said.
Farmers often continuously crop fields with salinity problems to use up the surplus moisture in the saline areas.
But drought combined with high fertilizer prices have many questioning the cost of seeding a crop on land that usually yields poorly anyway. Yet summerfallow would allow the wet, saline areas to expand.
Greenfix shines in the drier brown and dark brown soil zones, producing much more growth than the other registered green manure variety, Indianhead black lentil, which is better suited to the black and grey soil zones.
“Root nodulation on the chickling vetch is usually very good and results in greater N-fixation than with the black lentil,” said Steppuhn and Biederbeck in a newsletter.
“With timely rains and sufficient phosphorus, the nitrogen fixed by AC Greenfix on wheat stubble has reached 209 pounds per acre, compared to 63 lb. per acre by the Indianhead lentil in tests near Swift Current.”
The vetch also is more salt tolerant than pulse crops such as lentils or peas.
As for moisture management, the idea is to allow the crop to grow for two months, using up spring moisture in the saline areas and fixing nitrogen. It draws moisture from the top 60 centimetres of soil.
In early July, the crop is either disced into the soil in conventional till systems or killed with a desiccant in zero-till operations. That allows for moisture storage in mid-to-late summer.
“But if the rains that we do get are early and the tap dries off in August and the latter part of July, well, it wasn’t a summerfallow, really.”
The researchers said producers considering whether green manure fits their operation must weigh the seed costs against the value of the nitrogen and other matters such as expected rainfall.
“We can’t tailor make a recipe for each producer,” Steppuhn said.
But with nitrogen fertilizer prices linked to high energy costs, “why not grow it ourselves?”
With adequate moisture, the vetch can produce enough nitrogen for a wheat crop the following year.
In tests near Swift Current, wheat grown after a vetch green manure yielded as well as a crop grown after a true summerfallow and almost 60 percent better than on wheat stubble.
For more information, contact Biederbeck or Steppuhn at 306-778-7200 or by e-mail at sparc@em.agr.ca.
