WESTERN PRODUCER — Environmentally Smart Nitrogen has been around for about two decades.
Twenty years is a long time, so it’s easy to forget why Canadian farmers initially bought and used the polymer-coated fertilizer.
In the early 2000s, few people talked about greenhouse gas emissions from cropland, but farmers were concerned about something else.
“Probably the first reason it was used, when it was introduced, was for seed row safety,” said Lyle Cowell, a senior agronomist with Nutrien, which makes ESN.
“Twenty years ago, a lot of farmers had single shoot openers. ESN provides tremendous amount of seed row safety…. If you improve seed row safety, you’re going to improve the seedling stand.”
ESN uses a flexible polymer coating to encapsulate a urea granule that is 44 per cent nitrogen, says the Nutrien website. The coating releases the nitrogen slowly, based soil temperature.
ESN falls into the category of enhanced efficiency fertilizers, which are designed and marketed to reduce nitrogen losses to the atmosphere and cut leaching of the nutrient into groundwater.
The federal government is encouraging farmers to use these products because it is worried about greenhouse gas emissions and climate change.
The main greenhouse gas from fertilizer is nitrous oxide, and the federal government hopes to cut N2O emissions related to fertilizer by 30 per cent by 2030.
The 30 per cent reduction is voluntary and also controversial.
Many farm groups have said the emissions target is unrealistic.
Nonetheless, the feds are subsidizing the use of ESN and other enhanced efficiency fertilizers through the On Farm Climate Action Fund.
The Canola Council of Canada website explains how the program works.
“(The subsidy covers) the price difference between standard nitrogen fertilizer and fertilizer with dual inhibitor products … (and) the price difference between standard nitrogen fertilizer and polymer-coated urea (ESN).”
Nutrien has seen an uptick in ESN sales in Canada, thanks to the On Farm Climate Action Fund.
“Use of ESN certainly increased in the last year or two years,” said Cowell.
“The OFCAF money has provided some re-focus to it.”
The subsidy, though, only applies to fields where a farmer hasn’t used ESN in the past.
“It offers a farmer (a chance) to try a new practice — once,” Cowell said.
“It’s not a forever subsidy.”
The subsidy is encouraging a few growers to try ESN for the first time, but there already was an established market for it on Canadian farms.
Cowell said farmers purchase and apply ESN in a 30-50 per cent blend with urea for a variety of reasons:
- seed row safety
- better storage of fertilizer
- improved flowability
“Farmers like it because it flows through air drills,” Cowell said.
“With our system of seeding in Western Canada, it’s a pretty big deal for farmers to have good flowability.”
Some producers may like the better storage and handling of ESN, but all farmers care about yield.
If they’re going to pay a premium for ESN, most growers will expect a marginal yield increase to cover the expense.
If ESN reduces nitrogen losses, it seems logical that more nitrogen would be available to the plant, which would increase yield.
Bob Blackshaw, a retired Agriculture Canada scientist, conducted trials comparing ESN to urea at five locations in Alberta and Saskatchewan.
He found that ESN did boost canola yields, but not very often.
“ESN provided a seed yield increase over urea in 25 per cent of the cases and resulted in similar yields in the other 14 of 20 site-years,” the canola council says in a summary of the research.
Another possible benefit of preserving nitrogen in the soil might be to cut fertilizer rates. The logic is that enhanced efficiency fertilizers reduce leaching and gaseous losses, therefore a producer could cut fertilizer rates by 10 per cent and still achieve the same yield.
“It’s a theory, it’s right. But can we practice it? That’s a tougher (question),” Cowell said.
Turning the theory into practice is difficult because recommended rates of N aren’t engraved in stone.
There are field and soil fertility situations where farmers could cut rates of all forms of nitrogen and still achieve the same yield.
In other cases, that wouldn’t be a good idea.
“When we look at the big picture, we need to improve our predicted response (from) any fertilizer,” Cowell said.
“We’re not even in a place where we are that accurate to start with, with any nitrogen fertilizer.”
Consequently, “fiddling” with 10 pounds of nitrogen per acre isn’t an optimal practice, he added.
Data from the canola council website indicates that using ESN can reduce nitrous oxide emissions by 20 per cent on average, relative to urea.
However, N2O losses represent only a tiny fraction of nitrogen losses from the soil. As a result, there’s almost no agronomic benefit from cutting N2O.
“We probably only lose one or two per cent of nitrogen as nitrous oxide (in Western Canada),” Cowell said.
“There is a lot of focus on losses of nitrous oxide … but nitrous oxides are only part of the gases that can be lost through de-nitrification. There are other gases that are lost at probably greater (amounts) — N2 (nitrogen) by itself.”
Scientists from the University of Saskatchewan are hoping to pinpoint the total gaseous losses from nitrogen fertilizer in an upcoming research project.
“That’s the part we don’t know,” Cowell said.
“So far, we’ve been mostly guessing that number.”
If the researchers can nail down those numbers, growers and scientists might have a better understanding of nitrogen losses and how to improve the efficiency of nitrogen fertilizer.
“The general idea is to look at N lost as N2, which is not a greenhouse gas, but can be a more significant loss pathway,” said Richard Farrell, the U of S soil scientist who has proposed the research.
“Some data suggests that N lost as N2 can be as much as 10 plus times greater than N lost as nitrous oxide.”
Farrell is still waiting on funding for the project, so it may not begin until next year.
