Nitrogen stabilizer comes to Canada

Nitrapyrin-based product | Branded as N-Serve and eNtrench, it has been used in U.S. for 35 years

Dow AgroSciences is introducing a nitrogen stabilizer product in Canada that has been used in the United States for 35 years.


Dow announced in June that nitrapyrin, which reduces the likelihood of nitrogen loss through leaching and denitrification, is now approved for use in Canada.


“It’s been sold in the U.S. for about 35 years (and) used primarily on corn,” said Jeff Loessin, Dow AgroSciences Canada’s portfolio marketing leader for crop protection.


“In Canada, we’re bringing it forward for use on corn, canola and wheat, our high-use nitrogen crops.”


Nitrapyrin, branded as N-Serve and eNtrench, hinders the activity of a soil bacteria called nitrosomonas, which converts ammonium to nitrate.


N-Serve can be used with anhydrous ammonia and eNtrench is designed for use with liquid fertilizers and dry products such as urea.


Nitrapyrin keeps fertilizer in the form of ammonium longer, preventing losses that occur when nitrogen fertilizer is in the nitrate form.


“It’s an established product…. It does what it’s supposed to do. Basically it slows the nitrification process,” said Cindy Grant, an Agriculture Canada soil fertility specialist in Brandon. 


“The key niche for its usefulness in other areas seems to be with fall banding…. I think it is quite commonly used in Minnesota, those kinds of areas.”


Grant said nitrapyrin is distinct from urease inhibitors such as Agrotain because it acts at a different stage of the nitrogen cycle.


Nitrapyrin maintains nitrogen in the ammonium form longer, while urease inhibitors keep nitrogen fertilizer in the urea form. 


A 2004 study, which was published in Nutrient Cycling in Agroecosystems, evaluated data from the U.S. Midwest and concluded that nitrapyrin does reduce nitrogen losses through leaching and denitrification.


Grant said nitrapyrin is a proven technology in the U.S., but Canadian research isn’t as conclusive.


“Part of the reason they never had it registered here before is partly due to the fact that with our cold soils and relatively dry conditions … we didn’t get an economic advantage.”


The nitrosomonas bacteria are not active and nitrogen losses are less likely if a grower applies anhydrous later in the fall when the soil is cooler.


“Our recommendation is to put your nitrogen on after the soil temperature has fallen below 10 C,” Grant said. 


“That means the microbes have slowed down.”


Loessin said nitrapyrin allows producers to apply anhydrous earlier in the fall.


“It widens out that window,” she said.


“It gives you the opportunity to basically apply ammonia after harvest, any time, and you get that protection of your fertilizer source all the way to the next spring.”


Dow’s fact sheet says nitrapyrin slows the activity of the nitrosomonas bacteria for up to 10 weeks in warm soil, which is defined as soil temperatures higher than 10 C.


Manitoba Agriculture said on its website that products such as nitrapyrin are effective when soil conditions are wet or warm.


“If the placement and timing is not optimum and conditions are excessively wet, causing loss of nitrate-nitrogen, the cost of the products offering nitrification inhibition or slow release are beneficial,” the website said.


“The dilemma for the grower is that when application timing and placement are optimum and the weather is not conducive to loss, these enhanced products will provide no yield advantage over traditional N sources. Yet they all add cost.”