Researchers want to know how much is too much when it comes to side-banding urea in canola fields with wider row spacings.
When comparing fields with wide and narrow row spacing, each with the same volume of fertilizer per acre, wide rows have higher fertilizer concentrations because there are fewer of them.
The higher concentration of urea in wide rows leads to the question of whether it makes the soil too toxic as the urea breaks down into ammonia. That toxicity can hamper growth in canola fields
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“Hopefully we’ll have some good answers as to whether the problem is serious by the end of this year,” said Cynthia Grant, of Agriculture Canada’s research station in Brandon, Man. “If the problem is serious, we’ll try to correct it.”
A study looking at the issue began this year and runs for two more, with test plots at five research stations across the Prairies. For the study, canola was planted with row spacings of 22.5 and 30 centimetres. Urea was side-banded at rates of up to 143 kilograms per hectare. A no-till system was used on the plots.
Factors to consider
If it’s found that toxicity is a serious problem with the wider rows, further studies will be done to find solutions. Urease inhibitors, additives that slow the breakdown of urea, would probably be looked at, said Grant, along with different fertilizers and changing the application techniques.
Prairie farmers now use a wide range of methods to apply fertilizers to their fields. Urea is among the fertilizers used because it’s the least expensive of the granular products available.
The research is a spinoff from an earlier study sponsored by the Canadian Fertilizer Institute. The study, conducted by Ag Canada researchers, involved different fertilizer placements and row spacings.
“We were sometimes finding that our oilseed crop (canola) wasn’t performing as well with the wider row spacing,” Grant said.
Urea had been side-banded on rows 30 centimetres apart. The fertilizer was applied at rates that were two-thirds of recommended levels.
“We started to think that even with the relatively low amount of fertilizer we were using that we may have been getting some toxicity from our side-banded urea.
“The CFI study was significant enough that we were concerned.”
Problems with toxicity in canola can include poor germination, delayed maturity and a crop that’s less competitive with weeds.
“The stand doesn’t look as good or it doesn’t look as vigorous,” Grant said. “It can knock off a significant amount of yield and you might not even realize what’s going on.”
