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Liquid Gold

Waseca, Minn. — Minnesota may be sitting on an abundant, low-cost, high-nutrient fertilizer that’s easy to handle and available statewide. Better yet, it may reduce costs for farmer’s and one of state’s fastest-growing industries.

This mystery liquid isn’t actually all that mysterious. It’s just syrup — a soluble coproduct of dry-mill ethanol plants. Typically the syrup is sprayed on distiller’s grains, another ethanol coproduct, and dried for livestock feed.

Recently AURI initiated research to evaluate the liquid soluble as a land-applied fertilizer. “Most ethanol plants are looking for markets for the syrup because it is has relatively low value,” says Al Doering, who heads AURI’s coproducts lab in Waseca, Minn. “It’s a liquid, we’re in the middle of hog country, and farmers are used to handling liquid manure. We made the association and decided to test the syrup for its fertilizer value.”

Doering sent syrup samples to several independent labs and the AURI fats and oils lab in Marshall. Tests showed exceptionally high levels of nitrogen, potassium and phosphate — the NPK needed to fuel high-yielding crops.

Laboratory tests show the syrup contains 24 to 29 percent solids and is lower in pH than swine manure. Per 1,000 gallons, the syrup contains about 80 pounds of nitrogen, 89 pounds of phosphate, 63 pounds of potash (potassium), and about 8 pounds of sulfur — all higher than swine manure.

As with manure and commercial fertilizers, not all these nutrients are available to crops. But based on assumed nutrient availability, 1,000 gallons of syrup, with a $23 value, equals the same amount of commercial fertilizer, valued at $42, at current market prices.

Using solubles for fertilizer may save energy, as the syrup doesn’t have to be dried by the ethanol plant. Plus, the fuel used to produce and transport commercial fertilizers could be reduced.

“It’s worth looking at because we’re adding value to the syrup, potentially reducing the agronomic input costs to farmers, reducing drying time and costs for the distiller’s grains and returning a natural product to the soil as a fertilizer,” Doering says. “But we’re still early on and need to look at the economics to make sure it’s feasible … there are variables like transportation and application costs.”

Doering says the initiative’s second phase will likely involve university test-plot research including yield trials, nutrient availability, plant absorption and soil sample analysis.