With further price spikes and potential scarcity ahead, might it be time to try reducing costs and input requirements with variable rate application?

It might be – although a true reduction in required fertilizer volumes though a variable rate approach is unlikely.

WHY IT MATTERS: Refining how we use fertilizer supports crop quality and uniformity.

Variable-rate fertilizer application is an approach intended to match fertility treatments with the specific needs in different parts of a field, so knowing fertility levels in those different parts of the field is critical, says Chris Snip, an independent agronomist from Essex County.

Grid or zone soil sampling are both viable options, as are soil scanning technologies like SoilOptix and SWAT Maps. Indeed, Snip says “they all have their place.”

His experience suggests 2.5-acre grid sampling is an accessible and effective method for most of his clients, although SoilOptix can be valuable in fields with highly variable soils. He also points to cost-share programs, such as those offered through Ontario’s conservation Authorities, as valuable initiatives in reducing the cost of soil sampling and analysis work.

While urea is one of the products most impacted by current trade disruptions, it’s not necessarily one that can be effectively managed through variable rate application.

“I don’t have a lot of confidence with what’s out there today. I still think there’s a lot of stuff we don’t know about nitrogen and a lot of that variable rate stuff is how do we dial that it,” says Snip. Instead, he believes phosphorus and potassium are the primary nutrients to look at.

“Then you have to deal with someone to analyze the data and make it useful information. I like sitting down and having a conversation with the farmer about what makes sense. Down here in Essex, we tend to have a lot of legacy phosphorus – where an old farmyard used to be or areas that used to have vegetable production – that’s where you really get a benefit in changing the rate.”

Locally, Snip adds research from Agriculture and Agri-Food Canada Harrow points to an optimal range of 20 to 30 ppm for phosphorus. Beyond 30, and the amount of dissolved reactive phosphorus leaving the soil goes up significantly.

“Our approach is to build, maintain and drawdown. I always refer to nutrients in the soil as a bank account. We’re either putting money into that account or taking it out,” he says.

Equipment needs

If you’ve soil sampled, engaged an agronomist to analyze the data, and made a plan – then can your equipment do anything with it?

Variable-rate prescriptions require tractors and application equipment that can change rates to match a prescription. Ian McDonald, crop innovations specialist with the Ontario Ministry of Agriculture, Food and Agribusiness, says the capability of modern equipment to vary rates on-the-go is “quite amazing” today, but tends to be very large.

“Big equipment may not be able to vary across the toolbar, or the reaction time may not be what you want,” he says, adding “you have to have variation in the landscape to take advantage of variable rate.

“Variation isn’t always about changing soil type or elevation in terms of difference in crop response to fertility level.”

Managing smaller, more refined areas might remain a challenge, although Y-drop systems for repeated in-season applications have changed the equation for urea and UAN over the last decade. Looking ahead, McDonald anticipates advances in robotics will unlock the ability to apply nutrients in smaller quantities and on a smaller scale throughout the growing seas – something which could help alleviate nutrient tie-up in soil.

Snip adds the right equipment can open up new avenues of precision – fertilizer banding and strip till applications, for example. If a grower doesn’t have the necessarily capability themselves, custom applicators probably do. Neighbours might also be willing to lend a hand.

“Most people play nice together in the sandbox,” says Snip.

Misconceptions

The hard truth of variable rate, however, is growers should not expect to use significantly less fertilizer overall. The practice of redistributing more fertility to areas where it’s needed, and reducing fertility where it’s not, tends to balance out.

“We really saw an increase in more consistent yields from that variable rate…It’s not necessarily saving money, but putting it to better use,” Snip says. “It’s more about the right place when it comes to variable rate fertilizer.”

McDonald adds a variable rate approach can even increase the total amount of fertilizer applied, although that fertilizer is more strategically placed. Regarding nitrogen, he says another misconception is the economic range of nitrogen is narrow. In reality, the most economic range for nitrogen is around 25 pounds, with weather and moisture playing a key role in nitrogen availability.

“There’s an idea that if input rates are set to predicted yield potential of 200 bushels. But if everything lines up it could be 220 bushels. So you put on extra, a little insurance nitrogen,” McDonald says. That extra nitrogen, however, is not where an actual yield boost may come from.

“I don’t think that pays off … Your insurance was already built into the system through nitrogen mineralization.”

If a grower does want to experiment with different fertilizer rates, they have to know whether the experimental rate is actually responsible for the end result. McDonald continues encouraging growers to try their own on-farm rate trials with a zero-control check to identify actual fertilizer impact. Even small block checks, he says, can provide the necessary data to confidently “play with your rates.”

He adds data management remains an ongoing challenge, requiring growers to engage advisors to clean and interpret data before drawing impact conclusions. It can still be a worthwhile process, though.

“Farmers should find what they do best, and find the right people to optimize their system,” McDonald says.

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Financial pain can bring technologies and practices that were peripheral for many into sharp focus.

The rapid rise in fertilizer costs has been marked and could be the difference between profit and loss for some farmers this summer.

I’m curious to see if it will drive changes on farms.

Farmers don’t want to skimp on nitrogen as it is a major driver of yields, so they will err on the side of applying more than less.

A significant amount of money has been spent on fertilizer innovation, particularly in the area of nitrogen, over the past decade. Most of those solutions have a place, but aren’t mainstream.

This edition (April 7) features a couple of stories that address nitrogen options and a program to support the transition to split application. See them on pages 14 and 15.

The easiest way to manage fertilizer is to soil test. I’ve heard recent stats that less than 40 per cent of farmers soil test. You can’t manage what you can’t measure.

Variable-rate fertilizer is a technology that isn’t new, but it’s likely to gain more usage this year, as farmers think carefully about how better to manage the expensive input. This is a technology that won’t likely save you a lot in fertilizer costs, but it could help bump yield to pay for it.

Encapsulated fertilizer is another option to improve nitrogen use efficiency. Coating urea keeps it in place longer, hopefully so it’s there when the corn plant roots need it. The value is that the nitrogen is released slower and therefore doesn’t leach away and more of it is used by the crop.

Another practice that’s received mixed reviews is the split application of nitrogen. Instead of applying a full season of nutrients at planting, with a spreader and/or planter, 30 to 50 per cent might be applied at planting, then multiple other applications can be made, such as a sidedress at the V4 to V6 stage of corn. Wheat can also be sidedressed. Other farmers leave some of the nutrients to be added, if needed, up until pre-tassel, using high clearance sprayers with tubes that drop the nutrients at the soil level.

This practice is valuable for saving nitrogen, as the corn is usually tissue tested to ensure that the extra fertilizer is actually needed. Some years it will be, and there won’t be savings, but some years there will be.

There are programs to help with experimentation with nitrogen usage.

Farmers for Climate Solutions is administering an interesting program that helps guarantee a profit if you take the risk of using a second nitrogen application.

With today’s urea price, it’s likely worth the risk of a second N application, later in the season, but a program like this can make experimentation worthwhile.

How are you managing the high cost of nitrogen this year? Are you standing pat, or trying something new?

The post High fertilizer prices could drive innovation in application appeared first on Farmtario.

Several farmers talked about their 2023 trials at the Southwest Ag Conference in early January.

In Lambton County, Brad Podolinsky looked at three nitrogen rates in a corn field to figure out whether adding more nitrogen made sense for his farm. Rick Vandenbos, who farms near Binbrook, was looking for similar information.

The way the two tackled the problem was a testament to differences in equipment and environment on farms in Ontario and how those factors affect on-farm trials.

Podolinsky, who worked in conjunction with the Lambton Soil and Crop Improvement Association, used John Deere’s Operation Centre to record information on the project. He used three rates of nitrogen.

The normal treatment is a three-pass system: 30 pounds at planting, about 100 as a side dress and then 60-70 lb. with a y-drop system later in the season.

There is some variable rate application using the y-drop system because it has the capability, which the side dress applicator does not.

To run the trial, the application script was uploaded to the sprayer and liquid fertilizer was applied. Results were measured using the yield monitor on the combine and data was uploaded to the John Deere cloud-based system. 

“By the time I got back to the shop, it was already in Operations Centre,” said Podolinsky.

Total nitrogen for the three applications was 30 lb., 195 lb. and 230 lb. Yields were about 153 bushels per acre for the 30 lb. application, 200 per acre for the 195 lb. application and about 207 per acre for the application of 230 lb. of nitrogen.

The most surprising result for Podolinsky was that 30 lb. of nitrogen got him more than 150 bushels of corn. 

“I was a little shocked that 15 per cent of my normal practice got me 80 per cent of my yield,” he said.

He speculated that the amount of rain in that field caused nitrogen loss.

“I figure in my two higher rate zones, we lost a fair bit of N.”

His normal rate of 195 lb. as applied per acre still made financial sense based on $6 per bushel corn and the $500 per tonne cost of 28 per cent liquid nitrogen fertilizer. The extra 35 lb. of nitrogen would also have been profitable.

The results helped Podolinsky confirm the nitrogen rate he has been using.

“I don’t think we’ll change a whole lot. We might bump it up a bit, but I’m pretty happy with how the results show.”

 Across southern Ontario, near Binbrook, Vandenbos farms crops and hogs with two partners. He says the farm has traditionally applied a low rate of fertilizer, but wondered if that should change to get better yield.

The hog farm needs clean corn, so it’s critical to manage mycotoxins that produce deoxynivalenol (DON). That means yield isn’t the only driver in corn production on their farm and they did some fungicide trials in 2023.

Vandenbos says the farm has regularly conducted trials, but it is low tech compared to Podolinsky.

“I’m not a great IT guy, so a bunch of years ago we actually invested in scales for the grain buggy,” says Vandenbos. This allows quick access to data on small areas in a field.

The partners have watched how fungicides worked on the farm since starting to use them on corn in 2019. Last year, fungicides were an obvious winner in a wet year, he said.

Some trials showed a 15-bushel difference, although “it’s really hard to get fungicide to pay back purely on yield”, but the emphasis on reducing DON is important and that showed up in the treated versus non-treated plots.

The farm’s nitrogen trial was spawned by a program put together by Clark Agri Service to figure out what it would take to get to 300 bushels per acre of corn.

Clark Agri Service agronomist Johanna Lindeboom worked with Vandenbos on increased nitrogen rate trials.

“We’ve always been a bit on the skinny side on nitrogen and we were getting really good response on pounds of nitrogen on actual yields and she wanted us to see how far we could push it,” said Vandenbos.

Their total applied nitrogen is usually around 134 lb. per acre, which meant about 0.7 to 0.8 lb. of nitrogen per bushel of corn.

In 2023, tissue tests showed a need for more nitrogen so it was applied using y-drops. They also tried a high-yield test area with 40 gallons per acre of 28 per cent nitrogen liquid fertilizer, as well as an area of no additional nitrogen and an area with 15 gallons.

The result was a yield of 234 bushels per acre, which Vandenbos says is quite good for their area. But there was little gain from the additional nitrogen – about two bushels across the three strips.

“I was really disappointed with that because we said we’re gonna push it and we’ll see something substantial. However, it did tell us something. It’s not all in nitrogen.”

Like Podolinsky, Vandenbos expects that with late-season moisture and increased temperatures, a lot of the nitrogen was mineralized and not used by the plants.

The plan is to run a similar but smaller trial in 2024, and also look at other areas, such as starter fertilizer.

He encourages farmers to run their own trials because it contributes to learning and adds some fun to farming.

How much N are you losing?

Farmers know that not all the nitrogen they apply is taken up by crops. That’s a frustration because they’ve paid for that fertilizer and also because the excess ends up in the environment.

A Brant Soil and Crop Improvement Association project looked at the use of simple dosimeters to measure nitrogen loss.

A dosimeter measures types of radiation and is used by people who work in areas where they could be exposed to radiation. But dosimeters can also measure nitrogen loss in fields with some simple processes and shielding.

Holly Loucas of Corteva helped manage the project and talked about it at the conference.

She gave credit for paving the way to Greg Stewart, former OMAFRA corn specialist who is now with Syngenta, and Marijke Vanderlaan, also now with Syngenta, who conducted her master’s degree research on how to correlate nitrogen loss and dosimeters.

In the study, the dosimeter is clipped to a stake and then a pail with certain-sized and placed holes is put over the stake. The dosimeters turn a pinkish purple colour when sulphuric acid reacts with ammonia leaving the soil as the nitrogen volatilizes.

The parts per million reading can be recorded from the dosimeter and calculations run to determine nitrogen loss.

Tyler McBlain installed three of the units in a corn field at his farm. Two were in rows. One had added water put into the bucket as simulated rain and the other had no extra moisture treatment. The third bucket was in a row where the planter skipped, so it had more exposed soil.

Farmer cooperators checked the dosimeter daily to record the data.

McBlain wants to see more years of trial for the system, but his one-year takeaway was that there was less loss from the area that had full canopy than the one without and the one that had more water applied. That validates his decision to apply more nitrogen later in the year at a variable rate using y-drops.

Loucas was pleased with the results.

“I think in every situation where we had one in the field, we were able to measure nitrogen loss to some extent.”

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