Skip to content

Enhanced fertilizer can cut emissions

Enhanced efficiency products work, but few farmers are using them because they can’t find a way to make them pay.
Enhanced efficiency nitrogen fertilizer products can significantly reduce N20 emissions arising from fertilizer applications. Research found the largest emissions reductions are obtained from products that use a nitrification inhibitor, whether it’s alone or combined with a urease inhibitor. Products that just use a urease inhibitor, or polymer coated products, only reduce N2O emissions when applied in the spring. emissions arising from fertilizer applications. Research found the largest emissions reductions are obtained from products that use a nitrification inhibitor, whether it’s alone or combined with a urease inhibitor. Products that just use a urease inhibitor, or polymer coated products, only reduce N2O emissions when applied in the spring. | Robin Booker photo

WESTERN PRODUCER — Broad use of enhanced efficiency nitrogen fertilizer would achieve federal fertilizer emissions reduction targets, but there isn’t enough financial incentive for farmers to do this.

The federal government wants to reduce absolute levels of greenhouse gas emissions arising from fertilizer application 30 percent below 2020 levels by 2030, which is an attainable goal, said Richard Farrell, a University of Saskatchewan crops and fertilizer researcher.

“Enhanced efficiency products clearly can produce that emissions reduction. The question is how do you do that and pay for it? Because you’re not getting paid to save the environment, you’re getting paid to produce a crop,” Farrell said during the Saskatchewan Agronomy Update Dec. 14.

“There either has to be an incentive from the government to either help cover the cost of the premium, or some payment to come in that says, ‘OK, I’ve reduced my emissions by 30 percent using this product. I should get some sort of a subsidy or payment for that.’ ”

Farrell discussed ongoing research he’s involved with, including a study that sought the optimal rate of a dual inhibitor nitrogen fertilizer to reduce N20 emissions.

The study has a canola-wheat rotation with urea treatments of 70, 80, 90 and 100 percent of soil test recommendations, as well as treatments with a dual inhibitor nitrogen fertilizer product, SUPERU, also with rates from 70 to 100 percent of soil test recommendations.

SUPERU has both urease and nitrification inhibiting properties that protect against nitrogen loss.

“The (federal) emissions target is for direct and indirect emissions, and so a urease inhibitor basically prevents ammonium volatilization,” Farrell said

“It might not have as big of an effect on the direct emissions, but it has an effect on the indirect emissions.”

Using a line graph, Farrell described how N20 emissions were the largest in the urea treatment with the 100 percent of soil test recommendation application rate.

“It’s (line graph graphical representation of N20 emissions) a little bit bigger, it’s a little bit higher, It’s also broader. As you reduce the amount (of applied urea) the peaks narrow in, you’re still getting a high emission, but they don’t last as long, they come back down to background levels much quicker at the lower levels,” Farrell said.

Emissions in the SUPERU treatment are lower compared to urea.

“The (N2O emissions) peaks again narrow even more, and here reducing the (application) rate really didn’t change that too much,” Farrell said.

He said the study found the various treatments did not affect CO2 emissions or methane sink potential.

Canola yields were not affected, even with nitrogen inputs reduced 30 percent from soil test recommendations.

Wheat yields were also unaffected, aside from a small reduction when SUPERU was applied at 30 percent of soil test recommendations, but Farrell said he is not sure if this is significant at this point in the study.

A second study Farrell discussed examined enhanced efficiency fertilizers applied in a mid-row band in irrigated and non-irrigated wheat production.

The five main fertilizer products examined were:

  • ESN, a polymer coated product
  • a dual inhibitor product that had a urease inhibitor and a nitrification inhibitor
  • a product with a nitrification inhibitor
  • a product with two urease Inhibitors that affected different mechanisms
  • a product with just one nitrification inhibitor

With the fall applied urea treatment, emissions were low in the fall, but there was a large spike in N20 emissions during the spring thaw before seeding.

“Then you don’t see much (emissions) the rest of the way through the season because you’ve sort of blown off most of what you’re going to during that spring thaw period. With the spring application, you see the big peak after seeding,” Farrell said.

“You’ve applied the fertilizer, we get some rain and then we get another big peak, and then again things sort of tail off and you don’t see a lot of emissions as the crop grows up. It starts using the nitrogen and out-competes the microbial mechanisms that are there.”

He said even if there are large rainfall events in July or August, N2O emissions will be low because the crop will out compete everything else for nitrogen.

The fall applied enhanced efficiency products also had N2O emissions peaks in the spring.

“The biggest one (N20 emissions peak) is the polymer coated one. Then the next one is the urease inhibitor, then the nitrification inhibitor, and the dual inhibitor peaks get a little bit smaller,” Farrell said.

“With the spring application you see just a small peak because at that point you’ve got this early season rain, the crop hasn’t come up, but the fertilizers are protected so you’re not seeing large emissions.”

The spring-applied urea had emissions events the enhanced efficiency products didn’t have, indicating the products did what they were supposed to do.

Farrell said the products with the nitrification inhibitor, including the dual inhibitor treatment, were especially good at reducing emissions when fall applied compared to the other treatments.

“The nitrification inhibitor eNtrench and the dual inhibitor SUPERU were the ones that gave you the biggest reductions, and that’s over the two years, fall or spring applied,” Farrell said.

Irrigated systems typically get more fertilizer compared to rain-fed fields, and with the added water the potential for emissions is much higher on irrigated land.

Enhanced efficiency caused even larger emissions reductions on irrigated plots compared to rain-fed plots in the study.

“Within a rain-fed system we were seeing reductions of 40 to 50 percent in these spring emissions. In the irrigated one we’re seeing emissions reductions of 70 percent or more.

“What we’re finding is that you can achieve significant reductions with using an enhanced efficiency product. The largest reductions and the most consistent performance of all of them is products that use a nitrification inhibitor, whether it’s alone or whether it’s combined with a urease inhibitor.

“Products that just employed a urease inhibitor produce emissions reductions basically only when they were spring applied. They didn’t work at all with fall applications, and the consistency of the size of the reductions was a little more variable than it was with the nitrification Inhibitors. And then with the polymer coded one, we again only saw our emissions reductions when we put them on in the spring,” Farrell said.

Last year Farrell calculated a 15 percent premium that enhanced efficiency products have over traditional nitrogen fertilizer.

“There’s got to be some sort of economic incentive for all of this, and right now that just doesn’t exist. I mean, you can clearly go in and say, ‘OK, if the premium is 15 percent, I can use an advanced efficiency product and reduce the amount (of fertilizer) that I add by 15 percent. That covers my cost and I get a big (emission) reduction.’ But is that worth your time and effort to do that?”

He said few people use enhanced fertilizer products, which is part of the problem because the more they are adopted, the more companies will invest in manufacturing, which will cause prices to come down.