Saskatchewan agronomist Shannon Winny says many of her customers find a combination of ESN and urea provides a valuable return on investment in most years and under variable growing conditions.
ESN or Environmentally Smart Nitrogen is a controlled-release nitrogen fertilizer product first introduced by Agrium (now Nutrien) about 20 years ago. ESN is 44 per cent nitrogen urea contained within a flexible polymer coating. The breakdown of the coating, which is activated by soil temperature, releases nitrogen over 50 to 80 days.
The idea is for ESN to release nitrogen as the crop needs it, which can result in a protein boost in cereal crops midway through the growing season.
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Winny owns and operates GroWest Ag Ventures Ltd., an independent crop consulting business based in Harris, Sask. She provides consulting services over a couple of different regions with different growing conditions. Her husband farms land with his father and brother in nearby Rosetown and in Choiceland in northeastern Saskatchewan. Winny also manages all of the large plot research trials at the Ag in Motion Discovery Farm near Saskatoon.
“With my husband farming in two different parts of the province, I get to work with producers growing crops under different growing conditions,” says Winny. “It was pretty dry everywhere in 2021, but most years growing conditions are a bit drier in the Rosetown area, while usually we have more moisture at Choiceland. Each area has its own conditions and then of course each farm has its own preferences as well.”
Generally, when it comes to crop fertility in the Rosetown area, where more producers use single shoot seeding systems, her recommendation is to use a nitrogen blend that includes 75 per cent ESN with 25 per cent urea.
Winny says this blend can be safely placed in the seed row. Because ESN is coated, it is safe up to about two to three times the normal safe application rate of urea. Nutrien says if using 100 per cent ESN, it is safe up to three times the rate, while for a blend with ESN as 75 per cent of the total N, it recommends dropping back to two times the safe rate of urea.
“I recommend the 25 per cent straight urea in the seed row or very near (that) just so the crop has early access to nitrogen as it germinates,” says Winny. “ESN may release about 15 per cent of nitrogen early, but the majority is going to be released over that 50- to 80-day time frame.”
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She offers a different recommendation for producers in the Choiceland area. First, because of favourable soil and moisture conditions, it is common for farmers to apply a portion of nitrogen in the form of anhydrous ammonia.
Depending on yield targets, producers often apply about 90 pounds of anhydrous ammonia deep banded in fall and a blend of roughly 50 per cent ESN and 50 per cent urea at seeding.
“Along with the anhydrous ammonia, many producers have had good success at seeding with an additional 35 pounds of ESN and 25 pounds of urea placed in a side band close to the seed row,” says Winny.
Based on soil test recommendations and yield targets for a cereal crop, the combination of anhydrous plus the side banded ESN and urea works out to about 100 pounds of actual N.
“Again, the urea is providing that early nitrogen source to the germinating crop,” she says. “As the crop grows, the roots reach the anhydrous ammonia and the ESN releases as the soil warms up.”
Different circumstances
Winny says heavier clay soils in the Rosetown area aren’t as conducive for application of anhydrous ammonia, but another option is to float on or broadcast nitrogen in the fall or early spring. This can improve seeding efficiency and can also serve as a risk management tool.
Where fertilizer is applied in a separate field operation — anhydrous or floating — it can mean fewer stops to refill the fertilizer cart at seeding.
Winny recommends some ESN as well as about 10 pounds of urea be placed close to the seed row, with the rest broadcast before or after seeding. She notes there is a fairly wide window for broadcast application of fertilizer.
“With wheat, for example, farmers can float fertilizer on any time from fall right up to about the five- or six-leaf crop stage in the spring,” she says. “Some producers apply a portion of fertilizer in the fall along with some at time of seeding, and then they can monitor the crop and growing conditions to see if a top dress application is warranted.
“By splitting the fertilizer application, it is also nice to be able to hedge your bet a bit,” Winny adds. “Rather than apply 200 pounds of fertilizer up front and then only have about an inch and a half of rain and little or no crop, farmers can make that call whether to apply more fertilizer.”
Winny says as long as producers use nitrogen that has been properly stabilized, there is no need to incorporate broadcast fertilizer. She notes a number of nitrogen stabilizer products can be used to reduce the risk of N losses through denitrification, volatilization or leaching.
These products include Agrotain or SuperU from Koch Fertilizer. NexusBioAg has a line of Neon Surface nitrogen stabilizer products that can be used with urea. There is also YaraVera Amidas (40-0-0+5.5), a coated, granular, homogenous nitrogen and sulphate sulphur fertilizer. Winny says YaraVera Amidas technically isn’t a stabilized product but she describes it as “a fantastic product for floating in season.”
Winny appreciates that farmers must pay attention to input costs and return on investment, particularly with the high price of fertilizer these days but she notes that nitrogen stabilizer products provide value by improving nitrogen efficiency and reducing losses. She says another benefit is the way delayed nitrogen release can provide a protein boost in cereal crops.
Ontario research
While all farmers realize there are few guarantees, especially when it comes to growing season conditions, a longtime Ontario agronomy researcher says studies have shown a combination of ESN-stabilized nitrogen and urea or some other nitrogen source provides improved yields and economic returns.
Tarlok Sahota, director of research at the Lakehead University Agricultural Research Station in Thunder Bay, Ont., says after conducting and reviewing 10 years of research in Ontario, Western Canada and the U.S. corn belt, his recommendation today is still to use a combination of ESN with other forms of urea.
“A blend of the two fertilizers, urea and ESN, could prove better than either of the two fertilizers applied individually under (varying) growing conditions,” says Sahota. “Studies conducted on ESN in corn, wheat and other commodity grains elsewhere, especially in the United States, indicated that ESN improved crop output per unit of applied N, reduced N losses to the environment and gave growers greater control over the fate of applied N.”
Sahota says using ESN as part of the fertility program is particularly beneficial in situations where there is a risk of N losses due to denitrification and leaching.
Nutrien’s recommendation
Michel Poiron, marketing manager with Nutrien, says ongoing research has revealed the optimum recommendation for western Canadian farmers considering ESN is to use it in a blend with other forms of nitrogen such as urea.
He says some of the earlier recommendations were to use ESN as a 100 per cent nitrogen source depending on environmental conditions, but those recommendations have been updated.
“Research across Western Canada in recent years has shown that a 50:50 blend of ESN and urea is actually the sweet spot,” says Poiron. “It might vary slightly in certain circumstances, but in general and for most crops, including wheat and canola, that 50:50 blend produces the best results.
“In terms of yield and crop quality as well as economics and return on investment, we have found that a 50:50 blend is best,” he says. “With canola, research has shown a three- to four-bushel yield increase, and with wheat, for example, ESN is releasing that 10 to 15 pounds of nitrogen at the protein synthesis stage of crop growth, helping to improve crop quality.”
Poiron says ESN, as designed, generally doesn’t do much at seeding in early May because the ground is cool. But as the soil warms, it releases more nitrogen over a 70- to 80-day release pattern, with the all-important release happening as the crop reaches the protein stage.
With longer-season crops such as corn and sunflowers, the blend might lean heavier toward ESN — a 60:40 or 70:30 split — but for most other crops in the western Canadian environment, a 50:50 split is ideal, he says. And with that blend working well for most cereals and oilseeds, it makes it simpler for producers to apply to all crops.
“And farmers are recognizing that as well,” Poiron says. “They are seeing the benefit in crop performance as well as the return on investment. As we recommend that 50:50 rate, we have seen a 95 per cent retention among growers who see the benefit.”
Soil temperature is the main factor in releasing ESN, but Poiron says the product does work under dry growing conditions.
“It does require some moisture, but very little. Temperature is really the gas pedal,” he says. “Is ESN activated under dry growing conditions? If the crop is growing, then ESN is also working.”
