Didn’t get your fertilizer down last fall? What to consider this spring

Wet conditions mean you should pay particular attention to nitrogen


If you’re looking out your window at last year’s crop still in the field, you’re not alone — about four million acres went unharvested in Western Canada in 2019. And if you did manage to get your crop in the bin, maybe you couldn’t do much fieldwork before the snow and frost made it impossible.
All of this means that many farmers will be feeling the pressure this spring to iron out last fall’s problems — getting old crop off or putting fertilizer down, or both — before they can think about getting this year’s crop in the ground. And that, says Alan Blaylock, has implications for your fertility plan.
“If fall fertilizer applications have to move into spring, now your planting could be delayed, so maturity could be delayed, too,” says Blaylock, senior agronomist with Nutrien. “And if it’s another wet spring in 2020, well, these problems compound on each other.”
When and how to successfully apply fertilizer this spring will mean planning ahead to make sure you know exactly what you need, where you need it, and being ready to adjust your strategy depending on what Mother Nature decides to do. “If the spring is dry, we can get out there and get it done,” says Blaylock. But if it isn’t, here are some things he says you should think about when planning your fertilizer regimen this spring.

Soil-test now

“Phosphorus and potassium don’t change much from year to year,” says Blaylock. “They’re not mobile in the soil and are pretty stable. For nitrogen it’s a little more tricky — in wetter environments, that nitrogen is more transient and throughout the Prairies, we have potholes and wet spots that are prone to loss.”
So, after a wet spring in 2018, another wet and late spring in 2019 followed by that terrible harvest weather, 2020 is probably not the year to skip soil testing, he says. “With these extreme weather conditions, some of that nitrogen may have been lost through the fall and spring. It would be good to know if so and how much.”
Blaylock cautions farmers to be diligent with their sampling technique in order to get as accurate information as possible. “That soil test is a starting point for you to figure out what you’re going to do,” he says.

“Soil testing is not an exact science, it’s not prescriptive,” says Blaylock. “A soil test is an indicator of the probability you’ll get a response to fertilizer. The lab may make a recommendation, but they don’t know the details of your farm, so ask yourself what the soil test tells you, given all the other things you know. For example, if you have good soil moisture this year, maybe you should bump up rates to get a better response.”
Even a good spring offers a narrow window of opportunity to get fertilizer down — a window which could be even narrower if you were unable to get any put down in the fall, so make sure you start from a position of knowledge with soil test results in hand. “It’s a low-cost piece of information and very valuable piece of information, that doesn’t cost a lot compared to the fertilizer investment,” says Blaylock.

Spring application: three thoughts

Spring weather and conditions will determine a lot, but time is the real master when it comes to spring-applied fertilizer, so you need to think about potential scenarios and be ready for action when the time comes. Here are three things Blaylock says to think about.
Yield targets. “You may want to consider making adjustments to your yield targets,” he says. “Think about that yield goal seriously – is the crop going to be too delayed with reduced yield potential, or do you have good yield potential – and take that into consideration when picking the rate.”
For instance, should this wind up being another late and/or wet spring, think about how much time the crop physically has to take advantage of nitrogen uptake is from about the five-leaf stage through flowering in canola and from before jointing to heading in cereals,” he says. Applying fertilizer later than that will have a minimal impact on yield because the plants don’t need it anymore.
Typically, spring-applied fertilizer is more efficient, but getting 100 per cent of the crop’s needs down in time for the crop to take full advantage of it could be challenging in some circumstances. Adjusting yield targets to suit current growing conditions can help you pick a rate that will help the crop do the best it can in the time it has to maturity.

 Band if you can.  “Best management practice for cereals and canola is to put your nitrogen down before or at planting. In cases where moisture is uncertain, some may apply two-thirds or three-quarters of your fertilizer before planting, and the remainder after emergence but before rapid uptake,” says Blaylock. Side- or mid-row pre-seed banding is safer for seed and by far is the most efficient application method if conditions permit.
Pre-seed or at-plant banding is also the best method to prevent nitrogen losses through denitrification, where nitrate is leached away from the root zone, and gassing-off (volatilization), where ammonia vaporizes into the atmosphere.
Blaylock acknowledges that farmers who intended to put fertilizer down last fall may have anhydrous already purchased and will want to use it this spring if possible. “Anhydrous is very popular in the fall, but spring ammonia application takes more time than broadcasting and soil conditions have to be right,” he says. “If it’s too dry or too wet the soil doesn’t close properly to trap the ammonia.”
Alternatively, Blaylock says, if you have good moisture you could dribble-band UAN, which is often better than broadcasting.

Broadcast if you have to. “If the ground is wet and you simply have to get the work done, broadcast urea is the fastest way to go,” says Blaylock. “That comes with a certain set of risks, though.” Namely, a much greater chance of nitrogen loss through gassing-off. “If you are forced into broadcasting without any incorporation, one should probably use a urease inhibitor to avoid volatilization.”
But if you can broadcast before seeding and incorporate some with the seeder during seeding, this can be a viable way to get your crop properly and efficiently fertilized in a short amount of time. “You get better efficiency if you band your fertilizer,” says Blaylock. “But if broadcasting is what you’re left with, spring is a better time to do it than fall.”

For more resources on effective fertilization practices, visit https://www.nutrien-ekonomics.com/



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