On the market for just over a decade, ESN fertilizer was first adopted by Midwest grain producers. Almost all the product went to that region until some three years ago when the plant in New Madrid, Missouri, doubled capacity. That allowed new territories, like the Mid-South, to open up.

“All the ESN comes in from the Missouri plant,” says Louisiana-based Kelly Dupont, with Agrium. “When it arrives we filter out all the ‘fines’ to provide a really nice, uniform product. That receives a coating and is then shipped out.”

The physical coating applied to ESN protects against volatilization, leaching and denitrification.

“It’s a temperature-based product,” says Dupont. “So, you might consider putting some out in, say, September for ryegrass. We did some of that last year. The typical approach is to spoon-feed the crop (N) and split it into multiple applications. Well, ESN was put out all up front at planting and it lasted all winter.

“As the temperature heats up, it’ll release faster. With the ryegrass situation, if it’s rainy and cold, the grass isn’t growing anyway. The ESN just sits there, protected, waiting on sunshine and warmer days.

“Wheat is another crop where you can put out ESN early. Everyone is trying to hit the sweet spot of March 1, or whenever, to get the top-dress on their wheat. Well, oftentimes you can’t roll on March 1 – too wet or any number of things. You can apply ESN in January when the ground is frozen if you want. It’ll just sit there, waiting on the sun.”

Golden

Bobby Golden, Mississippi Extension rice and soil fertility agronomist, began working with ESN in 2004 as a graduate student in Arkansas. “So, we’ve been working with it for 11 years, although we haven’t looked at it in the same crops from year to year. Since 2010, we’ve spent the majority of our time looking at ESN on corn and cotton. In the last two years, we’ve also looked at it as a potential additional nitrogen source in soybeans.”

How does it work?

“A lot of the backbone of the research – and that’s from my time in Arkansas, then LSU and now Mississippi State – is in trying to determine the nitrogen release profile of ESN when placed in Southern soils,” says Golden. “That data has shown that, in general, in our warm climate and with application in an April timeframe with soil temperatures above 70 degrees, the product will release its nitrogen over about 35 to 40 days. It has a lag time of about three to four days after application before it begins releasing nitrogen. It will then steadily release the nitrogen over that 35- to 40-day window.”

The release mechanism requires a little moisture to kick it off. “But the release rate is temperature dependent. In most scenarios in the Mid-South, unless we’re applying it in early March, we’ll be in about a 40-day release window.”

Golden says data in laboratory conditions shows the warmer the temperature, the quicker the release. “In our labs, we’ve seen little to no difference in the release rate of the product whether you’re on a Sharkey clay or a sandier cotton soil. Soil texture hasn’t influenced the release of the product to date.

“We’ve looked at it on rice, corn, cotton and soybeans. Right now, in rice, we’re hesitant to recommend the product for use. There’s some hurdles to jump with the flood and application timings for us to use it in rice.”

ESN has looked “very promising in Mississippi for early-March planted corn. When we apply ESN at planting or shortly after, it looks really good with differing ESN/urea blends gaining 8 to 18 bushels per acre over nontreated urea.”

Dupont says ESN does very well in cotton. “Cotton is such a long-season crop that the ESN seems to stick around a bit longer and is there later in the season. 

“Really, where I’ve seen the most growth is in the forage market. The cattle ranchers have full pockets these days and so they’re fertilizing. With ammonium nitrate going away in most areas, they’re looking for a different fertilizer source. ESN is filling that void.”

Both Golden and Dupont say the comparison between ESN and Agrotain are inevitable. “Most everyone looks at ESN and says, ‘Hey, it looks like Agrotain,’” says Dupont. “Well, it isn’t. Agrotain is a good product, does what it is supposed to – prevent volatilization for seven to 10 days. That means if it rains tomorrow you’ve kind of wasted it. If you incorporate urea with Agrotain on it, that’s kind of foolish because you haven’t prevented your volatilization problem regardless.”

Golden digs into the chemistry between the two. “The active ingredient in Agrotain is NBPT – that’s what gives it efficacy. NBPT inhibits hydrolytic action on urea by the urease enzyme. Thus, NBPT effectively limits Ammonia volatilization by limiting hydrolysis.

“Where ESN differs from Agrotain is the control release coming from a physical barrier. When you put Agrotain on urea you’re stopping ammonia volatilization from occurring but the urea is still 100 percent available shortly after application. With ESN, you minimize volatilization loss, denitrification loss and/or leaching by slowly releasing small amounts of nitrogen over time. So, on day five after ESN application, say, 95 percent of the nitrogen hasn’t been released into the soil environment and is safe from N loss mechanisms.”

What about ESN application? 

“It’s a dry product and can be applied using standard equipment,” says Dupont. “It’s actually much better on the application side because it’s such a uniform product. You don’t have all the ‘fines’ and dust. It’s aerodynamic, so to speak, and there’s no segregation issues when it’s spread.”

Is there a lag time in terms of ordering ESN?

For the most part, producers can get a load immediately, says Dupont. “Of course, there are matters of logistics. If I’m trying to get a load to south Louisiana, how many trucks are coming down from New Madrid? In those situations, there can be a delay in trying to find a trucker willing to make a run south. So, it can take a bit of planning.

“There’s only been one time in three years where we’ve had to wait on urea to come up from New Orleans.”

More questions answered

Queried on typical questions from producers, Golden comes up with several.

First up: If I use this product can I reduce the nitrogen rate?

“My answer is no,” says Golden. “I wouldn’t reduce my N rate unless I was over-fertilizing to begin with. ESN is just an alternative mode of action to protect the N from various loss mechanisms.”

Second question: Is the cost of ESN worth it?

“Well, any nitrogen stabilizer is worth it if an N-loss condition occurs in your field. If you could tell 100 percent of what the weather will do – rain? Volatilization? Denitrification and leaching? – we’d know the product is worth it.

“Of course, there’s no way to know for sure. If you put out Agrotain on urea today and catch a one-inch rain and it’s incorporated you won’t get the efficacy out of the product. The same is true of ESN – if there’s no N-loss that occurs in the field you really don’t benefit from the technology. However, most of the time, a field will run into an environment where somewhere during the season after N application, an N-loss condition will occur. That’s when N stabilizer and enhanced efficiency products really shine.”

Golden and colleagues have seen good results with ESN by incorporating with a furrow plow sweeping out the middles. “ESN may, on very hard, compacted soils, may move across the soil profile and wash a bit on the end of rows. That can be solved with incorporating it with a furrow sweep. We’ve done that successfully in multiple trials.

“If we get a big, heavy rain, a lot of N sources can move off the end of fields. But because ESN is contained in a polymer capsule it can be physically seen. Other N sources can’t be seen once they dissolve.”

What about ESN qualifying for USDA/NRCS programs?

“ESN does qualify for the government programs,” says Dupont. “In fact, there’s a big buzz with ESN in the circles pushing for water quality. Since you don’t have immediate soluble nitrogen that has the potential to run off into a ditch and end up in the Mississippi River and, ultimately, the Gulf of Mexico, ESN is very attractive.”

Dupont says if you’re looking at ESN from a straight yield standpoint, “it’ll do well if you’ve got really good, strong, nutrient-holding capacity soils. However, other products might do well, too.

“Where ESN will shine is where you know you’ve got nitrogen loss problems: sandy soils where there’s leaching issues, heavy soils where there’s denitrification problems. It’ll also do very well in over-the-top volatilization situations where you expect a rain, put urea out, and the rain doesn’t come. All of the sudden, you’re 10 days in and volatilization rears up. ESN puts a stop to all that.

“Those more difficult fields are where you’ll see the yield separation. We’re seeing a lot of producers flying on extra urea because they know the field lost so much early this season. Meanwhile, ESN is still hanging in there, corn is green all the way to the ground and looks fantastic. At some point, when you’re doing rescue applications, ESN is a bargain.”

How can ESN be stored?

There’s very little shrinkage with the product, says Dupont. “Because it has the barrier, it’s waiting on some moisture – enough to grow the crop – but beyond that it’s strictly temperature-based.

“I live in south Louisiana and ended up with half a bucket of ESN sitting on my pier in all the humidity. It’s in a covered area but doesn’t have a lid on it. That bucket of ESN looks just like it did two years ago. It hasn’t turned into a rock and is just waiting to be spread. Retailers don’t have to worry it’ll turn into a concrete block in the back of a bin.”

There is one way you can set ESN up to fail, warns Dupont. “If you need nitrogen today, then since it’s controlled-release you need to consider other options. ESN will take seven to 10 days before it begins releasing.

“What happens is ESN will take a bit of water and turn into a sort of water balloon full of urea. As the temperatures heat up, the pores in the coating allow the urea to weep out.

“So, if you need nitrogen today, we recommend you blend ESN with some urea, some ammonia sulfate, some form of soluble nitrogen to provide that instant dose.”