Increase fertilizer efficiency to reduce GHG emissions

In a bid to reduce greenhouse gas emissions, the Trudeau government took steps in 2021 to lower emissions from on-farm fertilizer use. These measures included setting a voluntary emissions reduction target of 30 per cent from 2020 levels by 2030, which has some producers worried their farms may suffer if it means having to cut back substantially on the fertilizers they use to nurture their crops.

Is there a way the government’s ambitious emissions reduction goal can be achieved without sacrificing productivity and yield for farmers? When we asked a half-dozen soil nutrition experts that question, the consensus was yes — and, for farmers, it wasn’t necessarily about making do with less fertilizer, but being more efficient in how it’s used.

“I think there are plenty of opportunities using existing technology out there to reduce emissions to that point and maybe even more without even reducing fertilizer use or (sacrificing) yields,” says Wes Anderson, who is vice-president of agronomy at CropPro Consulting. “Not in every case, but there are situations where we probably could.”

Our experts had plenty of advice on how farmers could lower emissions by amping up their nutrient-use efficiency. Len Kryzanowski, who did agronomic extension, research and policy development work for Alberta Agriculture for nearly 40 years before retiring and becoming a self-employed agrologist, highlights the importance of the 4Rs.

Kryzanowski maintains any discussion around emissions reduction should start with farmers and agrologists examining the four pillars of 4R nutrient management and assessing how the source, rate, timing and placement of fertilizer applications can be made more efficient.

Banding better than broadcasting

When it comes to nutrient placement, there was general agreement that banding fertilizer is, generally, the best way to go.

Lyle Cowell, manager of agronomic services for Nutrien Ag Solutions, believes the focus for farmers should always be on banding rather than broadcasting nitrogen fertilizer, since it’s more efficient and has the added benefit of reducing nitrogen losses through processes like denitrification, volatilization and leaching, which are detrimental to the environment.

Chris Cavers, an Agriculture and Agri-Food Canada agronomist in Portage la Prairie, Man., agrees banding is usually a more efficient placement method for applying nitrogen, but he says farmers and agronomists need to be tuned into local conditions, such as field access during wet periods, which might require broadcasting fertilizer instead.

“In an instance like that, an agronomist could recommend, ‘Yes, broadcast, but broadcast a fertilizer with a polymer coating or a nitrification inhibitor to minimize your losses that way,’” Cavers explains.

Our experts agreed that nitrogen stabilizers like N-Serve or Centuro for anhydrous ammonia or eNtrench for urea, as well as slow-release products like ESN or SuperU, are useful tools for farmers for upping their fertilizer efficiency and reducing nitrogen losses.

Mario Tenuta, the senior industrial research chair in 4R nutrient management at the University of Manitoba, says nitrification inhibitors are already reducing nitrous oxide emissions on farm fields.

“By using nitrification inhibitors, we routinely see a reduction in N2O emissions, and it can even be more than 30 per cent,” he says.

Cavers likens nitrification inhibitors to an insurance policy for farmers and says they’re best reserved for areas in a field at higher risk of water problems like intermittent ponding or short-term flooding.

“Those are the areas where you’d want to use them,” he says. “There’s no point in using them on the drier parts of the landscape.”

Liza Britz, who works at Horizon Fertilizers near Humboldt, Sask., believes it’s important for sales agronomists like herself to steer farmers in the right direction. She says the number of products available to farmers to help fertilizers be more efficient can be overwhelming.

“I think it’s our job to really cut through all that and (to determine) what is a viable product, what really works and what doesn’t.”

Soil sampling and testing

Our experts also agreed that a key plank in building better fertilizer efficiency is soil sampling and testing, which provides a gauge of which nutrients are present in the soil and how much is available for uptake by crops.

“Soil testing provides crucial information for the calculation of the right rate of fertilizers to apply,” says Cavers. He maintains soil testing and other management factors that relate to fertilizer form, placement and timing will help to maximize crop uptake of fertilizer and minimize nutrient losses to the environment.

Cowell feels that in addition to the agronomic value of soil tests, a key selling point is they don’t cost very much. He says while farmers have various options for soil sampling and testing, the cost is generally insignificant compared to the total cost of producing a crop.

“You can buy your own soil probe and go sample your own soil, then sit down with a trusted agronomist and get a second opinion on the right (fertilizer application) rates,” says Cowell. “Or you can hire a consulting agronomist to do this for you and provide a more in-depth look at your rates. But in the end, soil testing really is not a big expense on a farm.”

Cavers says soil sampling and testing facilitates a more dialed-in approach to nutrient management by enabling farmers to do fewer blanket applications on entire fields and, instead, focus on the most productive areas of their fields where they can get the biggest bang for their fertilizer buck.

He believes it could also lead to more farmers and agrologists taking a hard look at those acres where yields can vary widely with changing moisture conditions or are consistently less productive — to see if the land can be used differently.

Tenuta agrees, adding soil tests can be used to tailor nitrogen management to microsite conditions or variable conditions in a field. He sees this as a tremendous opportunity to reduce emissions, particularly in depressed or sunken areas where there’s generally more moisture and more nitrous oxide produced.

“We’re at a very simplistic level when we’re talking about general management of acreage on the Prairies. Most farmers don’t sample every year for nitrogen, and most farmers manage all of their fields the same. I’m imagining, as we move into the future, we’re going to be able to see farmers being able to vary the nutrient source or provide an additive like a nitrification inhibitor on the fly,” Tenuta says.

“I really do see we’re going to have more complex management. We’re going to be moving to field by field. We’re going to be more interested in soil sampling on a continuous basis. We’re going to want to be sampling within a field for the yield and residual nitrogen, as well as for the response to added nitrogen and the response to different products or product placement within a field,” he adds.

“I’m seeing everything moved to a field-by-field level, and then within that field, the managers, the farmer and the consultant are going to be taking that precision agriculture approach,” says Tenuta. “Many farmers are early adopters. They like to push the bounds of what they’re doing and how they’re doing it, so you’re going to have change.”