Nitrogen inhibitors save money, improve yields: researcher

Harrow researcher Craig Drury uses a wind tunnel to compare the effectiveness of urease and nitrification inhibitors. It measures the level of nitrogen being released from the soil in its gaseous form.  |  Jeffrey Carter photo

HARROW, Ont. — Farmers have an opportunity to boost yields and reduce input costs with nitrogen inhibitors according to a research scientist at the Harrow Research and Development Centre.

“The return on investment is there. Depending on the year, I see a three-to-one to five-to-one return,” Craig Druy said at a recent open house.

“The inhibitors control the release of nitrogen in the soil. If you can control the release, you can minimize losses and enhance the nitrogen uptake by our crops.”

Drury has been evaluating the use of urease and nitrification inhibitors available in Canada and hopes to do the same with newer formulations from Europe. They use a chemical means to slow the biological process.

He’s also looking at how different farming practices affect nitrification.

“This has been a drier year in Ontario but we’re still having a considerable amount of loss from the soil, if the fertilizer is not incorporated or if inhibitors are not used,” he said.

Researchers have evaluated data from trials conducted in the sandy loam at the Harrow research location in southern Ontario’s Essex County in 2014 and 2015.

They show that a dramatic reduction of nitrogen fertilizer loss can be achieved and similar results are expected this year.

Drury used both urea and UAN (urea ammonium nitrate) in his trials, which he said now make up 74 percent of nitrogen fertilizer sales in Canada.

The greatest losses, more than 50 pounds per 100 acres, occurred when the fertilizers were surface broadcast. Inhibitors reduced the loss to slightly more than 20 lb. while the combination of injection and inhibitors resulted in a 97 percent reduction.

By trapping nitrous oxide as it escaped, Drury was able to put a dollar figure on the different approaches.

When the broadcast method was used with no inhibitors or incorporation, more than $3,000 in ammonia was lost over 100 acres.

That was reduced to $1,320 with the use of inhibitors, to $1,490 with injection and to $38 with a combination of injection and inhibitors.

There were also differences in yield.

When fertilizer was broadcast with the urease inhibitor, there was about a five bushel gain over broadcast fertilizer alone in both 2014 and 2015.

By using both the urease and nitrification inhibitors with broadcast application, yields were even higher.

The greatest yield benefits came when the urease and nitrification inhibitors were used in combination, regardless of the fertilizer application system.

“What’s happening is the fertilizer is going to the crop instead,” Drury said.

“They are pretty new, the inhibitors. It takes a while for any technology to be taken up. Some of the innovators in the agricultural community are using them.”

Similar results are expected from the 2016 plots, although they had yet to be harvested. The research continues next year.

Paul Cornwell, a certified crop adviser with the Hensall District Cooperative, said inhibitors are most likely to be used with UAN.

An alternative to inhibitors are fertilizer coatings like environmentally smart fertilizer, he said.

Uptake of inhibitors tends to be impacted by the price of nitrogen, Cornwell said.

When prices are low, farmers may decide to in-crease their nitrogen rate or forgo inhibitors.

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