21 Days will make or break corn yield
Corn needs a reliable season-long supply of nitrogen. Can it be done?
Every farmer accepts that a fairly hefty portion of the nitrogen they put down never makes it to the crop. That’s just how nitrogen is – some of it will leach away, some of it will gas-off (volatilize) into the air and some of it will be taken up by the crop, where it contributes to yield.
While this nutrient loss is simply a given for most farmers and something they calculate into N application rates, putting numbers to it can be a bit shocking. In the case of corn, roughly 40 per cent of soil-applied N doesn’t make it to the plant. Nearly half!
Not only that, at the same time plant-available N in the soil is on a downward swing, corn is ramping up its demand. It’s why many corn growers plan a nitrogen side dress later in the season. But how much of that N makes it to the plant and how much is lost?
Given the importance of nitrogen to corn yield outcomes, and its cost, farmers are right to focus on ways to get the most out of what they apply. The question is how?
What the corn wants
This focus on nitrogen losses and nitrogen efficiency in corn has intensified over the last few years – indeed, it is one of the most researched subjects in corn production today. The challenge has always been to find ways to mitigate N losses while improving efficiency, and there are no easy answers.
Work done by Dr. Fred Below, professor of plant physiology at the University of Illinois, has certainly helped to clarify the challenges. His “Seven Wonders of the Corn Yield World” focuses on what he sees as the seven key factors that contribute the most to achieving an ideal 15 700+ kg/ha corn yield.
The top two factors on Below’s list, both of which he says can influence yield by 4400 kg/ha or higher, are weather, something no one can do anything about, and nitrogen, something everyone can do something about.
Like most crops, corn needs a season-long supply of nitrogen, but it’s around the V6 stage when plants really start to increase nitrogen intake in preparation for the reproductive growth stages.
Further, the most important growth stages for yield determination are from V10 to R1, a roughly 21-day period from about the third week of June to the second week of July. According to Below’s research, corn needs at least 7.8 kg of N per ha per day during this specific yield-building period.
This is the critical point for nitrogen availability. If corn doesn’t get that seven pounds per day for the full 21 days, you’re leaving yield on the table. So how do you avoid that?
The most important growth stages for yield determination are from V10 to R1, a roughly 21-day period from about the third week of June to the second week of July. According to Below’s research, corn needs at least 7.8 kg of N per ha per day during this specific yield-building period.
Achieving a constant supply of N
Typical practice is to apply nitrogen to the soil in fall or spring, before planting, followed by a supplemental application around the V6 stage – usually with a liquid nitrogen product applied as a side dress or, increasingly, with a Y-drop applicator.
But here’s the thing: nitrogen, while a highly mobile nutrient, tends to move only one way in the soil – down. It has limited side-to-side movement, which means your second application has to land pretty much right on top of the roots to be useful. The Y-drop applicators are better at this than other methods, but leaching and volatilization are still an issue.
There are other factors with side dressing, too, that make it less than ideal including the time and fuel costs of an additional field pass and the soil compaction that comes with that, which also impedes N uptake.
But the fundamental challenge that remains - how to ensure, out of all you’ve applied, there is a constant supply of at least seven pounds of available nitrogen per day during that crucial 21-day, yield-determining period.
Nitrogen stabilizers help, as do application rates and timing. But none of these can ensure a constant supply of available N. A rain event, a drought, too hot or too cool temperatures, or any number of crop stressors – can all mess with nitrogen availability, uptake and utilization.
But there is a new tool in the nitrogen application toolbox that does actually help to address this challenge. It’s called Envita and it, essentially, allows corn plants to fix their own nitrogen on a continuous basis.
Envita is a naturally occurring, food grade bacteria that’s applied in-furrow or as a foliar spray. It enables cells throughout the plant, both roots and foliage, to fix their own nitrogen from the air.
Say what? Of all the sources of nitrogen available to plants, air might be one of the most overlooked. Air is 78% nitrogen and the Envita bacteria naturally metabolizes that N and makes it available to the plant. Envita grows with the plant, too. It doesn’t leach away or wear off, which means that this is the first solution to provide a constant, season-long nitrogen supply to the plant, making it a real game-changer for corn farmers.
And they have options, too. Farmers can add Envita to their regular N program and aim for even higher yields, or they can use it to reduce their N fertility program while maintaining yield targets. In 2020 field trials, Envita boosted corn yields, on average, by 376 to 502 kg/ha on maize and by 269 to 336 kg/ha on soybeans.
A modern tool for an age-old problem
It’s worth pausing for a moment to consider how technologically advanced corn has become in the last few decades. Advanced breeding techniques and constantly improving germplasm have led to some pretty spectacular field performance and productivity gains across the board.
While it’s easy to get lost in the bells and whistles of modern corn hybrids, what hasn’t changed are the basics of corn production, and that’s Below’s point with his Seven Wonders: a 15 700+ kg/ha yield is possible today, but the genetics can only take you so far.
Crops still have to be in the ground by a certain time, still need protection from various pests and still need to be fed properly. So even if all the nitrogen a corn crop needs is right there in the soil, it’s only as good as the plant’s ability to get it to where and when it is needed most and, as every farmer knows, there are not too many days that a crop isn’t dealing one stress or another.
By taking nitrogen from the air and topping up what your crop isn’t getting from the ground, Envita is already where and when corn plants need it, able to fill in any gaps in N supply, especially during that critical 21-day period that can make or break crop yield.