Nutrient Experts Share How to Save $$ on Fertilizer
Published: Friday, April 4, 2025
Applying only as much fertilizer as your crops need is important for two reasons, experts say. First, with high fertilizer prices, growers can't afford to apply excess nutrients. Second, it's the right thing to do from a water quality perspective.
Jon LaPorte, Michigan State University Extension educator, and Kurt Steinke, nutrient management specialist with MSU, both addressed that topic during the Michiana Irrigated Corn and Soybean Conference on March 5 in Goshen.
For years, farmers have been told to follow the Build-up and Maintain app-
roach, meaning they should add enough fertilizer, year after year, to keep phosphorus (P) and potassium (K) at high levels. Once the critical soil test level is reached, fertilizer recommendations are based on maintenance and keeping those nutrients at a high level for the long-term.
"The problem we found is that you're going to have leaching," LaPorte said.
Another problem was that growers weren't seeing a yield response to those high soil tests.
"With the excessive nutrients in the soil, you were spending a whole lot of money to put nutrients out there that you were just turning around and losing," he said.
Since then, most fertilizer recommendations have shifted to a Sufficiency Level of Available Nutrients (SLAN), LaPorte said.
With SLAN, farmers apply the minimum amount of fertilizer needed to reach the maintenance level, according to LaPorte. The main idea is to keep soil nutrient levels in balance.
When you're studying your soil test, LaPorte said the ideal recommendation for phosphorus is 80 pounds. For potassium, the goal is 260 pounds (if the cation exchange capacity is below 5) or 370 pounds (if the cation exchange capacity is above 5).
"The idea is that when you hit those numbers on your soil test, don't add any more fertilizer, regardless of what you may be used to," he said.
Steinke addressed the economic realities of the fertilizer market. He said fertilizer prices are much higher today compared to the "good old days" of just five years ago. In 2020, farmers paid just 39 cents a pound for nitrogen; five years later, they're paying 60 cents a pound. Both phosphorus and potassium are also higher in price.
Fertilizer is a world commodity. When there is volatility around the world, it tends to affect the prices U.S. farmers have to pay. For nitrogen, the U.S. imports roughly a third of its supply. China produces 40% of the world's supply of ammonia but has cut back on nitrogen exports so it can meet domestic needs. Russia is the world's No. 2 nitrogen producer.
COVID, hurricanes, war, plant shutdowns, tariffs and logistical factors create volatility for the nitrogen market. If any of these factors happen at the same time, it can create a price spike in the market.
Farmers can absorb high fertilizer prices when prices are around $6.75 per bushel, as they were in 2023. However, corn prices are now hovering just above $4, leaving farmers unable to cover those high costs.
The U.S. imports 25% of its phosphorus needs. Farmgate prices have increased from 39 cents per pound in 2020 to 74 cents per pound in 2025.
For potash, the U.S. imports 85% of its supply. Most of that comes from Canada. Prices have increased from 29 cents per pound in 2020 to 37 cents per pound in 2025.
Steinke said tariffs could add as much as 25% to the cost of imported fertilizer. For farmers, that could increase the cost between $100 and $200 per ton.
He added that farmers could see a "substantial difference" in prices depending on when the product was purchased—last fall or this spring—by their supplier.
Last year, both Indiana and Michigan saw record corn yields. Steinke said the good crops were the result of soils warming up earlier than usual in the spring, allowing farmers to plant crops earlier.
The last day with soil temperatures below 50 degrees F in the Lansing area was April 27. By contrast, farmers couldn't get in the fields in 2023 until May 27.
"When soil temperatures get north of 50 degrees, the biology kicks in and we start mineralizing some nutrients," he said.
Another factor contributing to record corn yields, Steinke said, was consistent moisture throughout the growing season. In some places it was too moist, but, overall, both Michigan and Indiana had good rains.
In addition to the warm soils, available moisture and early planting was early nitrification, a biologcal process that transforms nitrogen into a form that plants can use. Nitrification happened very rapidly last year.
"Conditions that support mineralization of nutrients, those are the years that also tend to support greater formulas," he said.
He said it's something that happens only once or twice in a decade. The last time it happened in Michigan was in 2016.
"The weather worked in our favor for the most part," he said.
Early planting also improves soybean yields.
"As you go north, you gain a bushel a day before May 9 or May 10 in our neck of the woods," Steinke said.
But the MSU specialist shared a recommendation for late-planted beans. His research shows that starter fertilizer makes a big difference—as much as a 9 to 10 bushel per acre increase —on soybeans. The best response was observed on sandy soils with good water availability.
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