ESN Makes Single Shoot Safer

The drawback to single-shoot openers, says Ken Coles, is that they limit the amount of seed-placed fertilizer you can put down safely. As general manager of the Southern Applied Research Association (SARA) based at Lethbridge, Coles is looking out for farmers in his area — trying to save them some cash if he can. “The options were either make a second pass to put down fertilizer or move to a double shoot opener,” he says, both of which add costs without adding much value.

With the advent of polymer-coated urea, in this case Agrium’s ESN product, a third option becomes available: Keep your single shoot opener and bump your seed-placed fertilizer rate without harming stand establishment. But how much nitrogen can you put down safely? Is the sky the limit? Do you need to treat all or only some of the urea? These were questions Coles set out to answer.

Over three years, 2007 to 2009, Coles and his team evaluated three opener types, four nitrogen rates (zero, 30, 60 and 90 pounds per acre) and four ESN levels to try and find the upper limit of seed-placed fertilizer in a single opener system. The trial pitted a disc opener (seed bed utilization of roughly seven per cent) against a narrow knife (one-to two-inch spread) and a three-inch spread on 10-inch row spacing (30 per cent seed bed utilization.) ESN was used in four rates: none, 100 per cent of N applied, a 75 per cent ESN to 25 per cent untreated urea ratio, and finally a 50:50 ratio. All rates and openers were tested on canola establishment.

It’s important to note these trials were set up on land that had a very high background soil nitrogen level, making it a great set up for evaluating the effect of plant stand establishment on yield as related to seed safety versus availability of nitrogen. All trials were under dryland production.


“We haven’t finished our analysis as of yet, but our preliminary

Ken Coles says their trial results show a correlation between stand establishment and yield. “The general thinking is that canola will branch out and overcome a thin stand, but that’s not always the case,” he says. “Plant population is still important when we’re talking yield potential.”

findings suggest some definite trends,” Coles says. For starters, it’s clear that for the disc and knife opener, each increment increase of ESN improved plant stand numbers. “There was a clear order for these openers,” Coles says, “ESNtreated fertilizer was always safer.”

What’s interesting is that independent of ESN use, the higher the seedbed utilization, the higher the plant stand numbers. In some cases, the three-inch spread with no ESN fared just as well as the same opener with ESN, Coles says. The message here is higher seedbed use adds safety, regardless.

Timely rains have the same effect. “A good half-inch of rain a few days after seeding improves seed safety as well, but you can’t count on that and that’s where a product like this becomes risk management,” Coles says. That said, the three-inch spread with ESN had the best establishment overall.


The positive correlation between ESN use and stand establishment is pretty clear, according to Coles. “There’s no question that seed safety and stand establishment improved with ESN use in all cases, however that didn’t always translate to more yield,” he says.

It seems that in a drier year, like 2007, the better plant stands — those that received some percentage of ESN — did out-yield the others. “In that year, the ESNtreated disc and knife plots had higher yields, but there wasn’t a significant difference in yield in the treated and untreated three-inch spread plots,” he says.

“There is a correlation between stand establishment and yield. The general thinking is that canola will branch out and overcome a thin stand, but that’s not always the case,” Coles says. “Plant population is still important when we’re talking yield potential.”

A better growing season, like ’08 and ’09, diminished yield differences between the plots. “Yields overall were nearly three times those of 2007, however the differences between treated and untreated plots really averaged out in 2008,” Coles says. “This past year, we seeded late (mid-May) and had good growing conditions. The yields weren’t as good and weren’t much different between plots.” He adds, however there was a significant difference in plant stand numbers.

The trial did prove that without ESN, 90 pounds of seed-placed N depressed yields, however up to 60 pounds of N did seem safe with all openers in 2009. Conversely, in the drier 2007, nearly all plots without ESN had lower yields. “As fertility rates increased, yield decreased unless 100 per cent treated with ESN,” he says. He adds that it didn’t seem to take a lot to hurt yield in a drier year.

Stand establishment itself is a risk management tool, Coles says, and one that shouldn’t be ignored. In this trial the researchers were only measuring plant counts and eventual yield but Coles cautions that there are other factors, such as disease pressure or insects, that could significantly knock back a crop. A healthy start and higher original plant counts means more yield potential protection.


“The great thing about on-farm trials,” Coles says, “is that you can tailor it to your own questions and management.” Most farmers aren’t going to evaluate three types of openers, however he recommends looking at SARA’s findings and applying them to your own farm.

“If you typically put down 120 pounds of N with a three-inch spread on canola, maybe try treating 75 per cent with ESN,” he says, thus bringing the seed-placed rate down to 30 pounds, which seemed safe in the trial. The most important thing, Coles says, is to leave a check strip and track where you made the changes on your GPS and use your yield monitor (GPS-equipped is ideal) to judge the difference.

“If you don’t leave a strip you won’t see what happened,” he says. After noticing such a significant impact on seed safety in a dry year like 2007 and considering the high cost of hybrid seed, Coles says it just makes good sense to test out the safety of seed-placed rates on your own fields.

Lyndsey Smith is a field editor with Grainews. She’s based in Lumsden, Sask. Email her at [email protected]

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