Your 4R fertilizer management plan for 2021

Doug Hofmann soil tests every field every year. The farmer from Muenster, Sask., doesn’t have to soil test every year to be 4R compliant, but he does it anyway. “For the cost, I don’t even think about not doing it,” he says.

He has a GPS-marked sampling location for each field, and he goes back to that same area each year. He will sample more intensely in fields where yield maps show possible problem areas. For fields that are new to the farm, he samples nine locations per quarter and submits separate samples for each location. “That gives us a better idea what the land needs, and we can pour the coals to it,” he says.

For canola acres, Hofmann uses a phosphorus-potassium-sulphur blend of 0-40-10-15, and sets the rate for each field based on soil test results. Nitrogen is applied using variable-rate mapping.

With his long-term and intensive fertilizer program, Hofmann says soil test results have become fairly similar for each field, but he still won’t stop testing every field every year. “It helps us fine-tune things,” he says. Fine-tuning for 2021 will include an adjustment on sulphur rates. “We’re running into a bit of excess sulphur in some fields, so we’ll cut back a little bit in 2021.”

Hofmann develops his fertilizer strategies with help from Sara Lemmerich, an agronomist with Nutrien at Humboldt, Sask. Lemmerich has her 4R designation from Fertilizer Canada. She’s also a certified crop adviser (CCA) and might try for the new CCA 4R designation in 2021. “This is a logical step,” she says.

Nutrien takes a company-wide approach to 4R and has quite a few staff agronomists with their Fertilizer Canada 4R designation. With this designation, agronomists can help growers get their acres counted under the 4R program. The Canola Council of Canada would like to see 90 per cent of canola acres using 4R practices by 2025 – as a way to demonstrate positive production practices for Canadian canola.

Lemmerich says working with Hofmann and other farmers on their 4R practices is “leading to good conversations” on fertilizer rates, sources, placement and timing.

Of the 4Rs, she says rate is one that “can always be reexamined.” Nitrogen rates get a lot of the attention, but phosphorus rates are “often forgotten about”, she says. A lot of farmers will apply 25 to 30 lb./ac. of phosphorus because that is the rate they’ve always used, but what is the crop removing? “We’ve been seeing a lot of 50 bu./ac. yields over the past few years, which means phosphate removal could be up to 60 lb./ac. per year,” she says. That helps to explain why phosphorus levels are so low.

Except for Hofmann’s. He has built up soil phosphorus levels to the point now where he doesn’t feel the need to use seed-placed phosphorus. “We don’t put any fertilizer at all in the seed row,” he says.

Lemmerich says seed-row placement often comes up in her conversations with farmers, and some are surprised about the possible crop damage that can come from higher rates of seed-placed fertilizer. “Reducing fertilizer in the seed row will be especially important in 2021 if the spring is dry,” she says. Dry soils increase the risk.

Basic 4R principles

Farmers can review 4R principles at fertilizercanada.ca. The “basic” level practices include a recent soil test (in the past three years) to establish a baseline for soil phosphorus levels and tools “such as nitrate soil tests” to set crop- and field-specific nitrogen rates. Basic practices also say that “any nitrogen fertilizer” source can be used if that source is applied in spring or in-season. Banding is generally considered the best placement, but broadcast with incorporation is acceptable. For nitrogen, basic 4R practices specify that farmers should “avoid fall broadcast of unprotected nitrogen”.

Hofmann applies all of his fertilizer in one pass at the time of seeding. He uses the standard fertilizer sources and puts it all in the side band. With side-band placement, fertilizer is within easy reach of plant roots and “it’s not going anywhere”, he says. “It goes into the ground and I know exactly where it is.”

He applies all fertilizer at the time of seeding because top-dress has risks — especially for timing. “By the time you realize the crop needs more fertilizer, application is probably going to be about 10 days too late,” he says. Also, with all fertilizer in place at the time of seeding, he can focus his in-crop efforts on weed, disease and insect management.

Hofmann learns a lot from running plots and trials on his farm. “I like to try different things and with the trials, I get to see the new stuff first hand. I get to see how it was seeded and the rates. I get to see the truth behind it all,” he says.

Lemmerich says Nutrien has done a lot of canola trials with Hofmann over the years. “Doug is our guinea pig guy,” she says.

For variety plots in particular, Hofmann uses the opportunity to try out higher nitrogen rates. His usual average across the farm is 90 lb./ac., but he’ll use 150 lb./ac. on the seed plots to see how the varieties stand up and perform.

As a result of these trials, he wants to try higher nitrogen rates in some spots in 2021. After years and years of harvest data, he has mapped the high-productivity acres where he’d like to try higher nitrogen rates. His variable-rate application system makes it an easy adjustment.

In the interview for this article, Hofmann actually used the word “cheap” to describe fertilizer. It’s the biggest input cost on the farm, but he calls it cheap because the return on investment is so clear. This is why he’s always looking for ways to push for higher profitability. After years of soil testing, yield mapping, on-farm trials and discussions with advisers like Sara Lemmerich, he has come to the conclusion, “I think we can do more with fertilizer.”

For more on canola fertilizer needs, read the article “How much fertilizer does canola need?” at canolawatch.org.