Farmer Cuts Herbicide Bill by Adding Soybean Oil to His Weed Killers

At first, Gene Hood was skeptical. A friend and fellow farmer in Indiana was adding soybean oil to his herbicides. By doing so, he was able to cut back on the amount of weed killers he sprayed on his fields.

At first, Gene Hood was skeptical. A friend and fellow farmer in Indiana was adding soybean oil to his herbicides. By doing so, he was able to cut back on the amount of weed killers he sprayed on his fields.

After hearing about what his friend was doing, Hood, who farms north of Gifford, didn't exactly run to the farm supply store to load up on soybean oil.

Then one year in the early 1990s he had to respray herbicide on 780 acres. And he learned the chemical company that supplied him with the herbicide would no longer guarantee the product, meaning Hood would have to foot the bill if he needed any more re-sprays.

What the heck, Hood thought, he'd give the soybean oil a try.

Since then, he's been adding processed soybean oil to the herbicides that he sprays at planting time and later when the crops are up and growing. This year Hood estimates he'll save about $25,000 by reducing the amount of herbicides he sprays on about 2,000 acres.


"It's worth messing with," said Hood, who mixes the soybean oil with the herbicide before adding the substances to water and heading out to the fields.

What he does is essentially reduce the recommended rate of application. For example, the chemical manufacturer's recommended rate of a particular grass killer was 1 ounce per acre. Hood used one-quarter of an ounce.

What prompted him to do such a thing was the potential to save money. But he also feels pretty good about reducing the amount of chemicals entering the environment.

"It's got to be better for the ground. You're putting less chemical out there," Hood said.

Over the years he's tried adding soybean oil to several different kinds of herbicides sprayed at different times of the growing season. Eventually convinced of its effectiveness, he started buying the oil wholesale and selling it to other area farmers. This year he sold about 4,000 gallons.

It can be a tough sell. Many farmers choose not to spray themselves and instead hire an application company to handle it all. Or the farmers remain satisfied with a chemical company's guarantee.

By not following the recommended rate, "you take all the liability," said Earl Williams, a soybean farmer from Cherry Valley and president of the Illinois Soybean Association. "A chemical company will often back up use of their product only if you apply it according to their rates, what's printed on the label. If you're doing an off-label application, they won't back it up," he said.

But that doesn't matter to Hood, who hasn't had to respray herbicides since he started mixing in soybean oil.

Soybean oil is one of a slew of additives for herbicides and pesticides, said Aaron Hager, University of Illinois Extension weed specialist.

How do they work?

Imagine a drop of water on a freshly waxed car. It usually sits there on the surface. Well, a leaf is covered with a waxy surface. When the herbicide hits the weed's leaf, it could sit there like a nice round ball of water on a waxed car. To increase the amount of surface area the chemical comes into contact with, chemical companies or farmers mix in additives such as ammonium sulfate or substances called nonionic surfactants, Hager said.

(Why even bother to control weeds? Weeds are hogs. Not only do they take up space in the field, but they soak up water and other nutrients that farmers would rather see go to their corn and soybean plants.) Just how effective soybean oil is as an additive to herbicides, particularly herbicides applied at planting time, is up for debate in the farming and academic community, Hager said. He's never seen any third-party data that indicate an additive improves the performance of an herbicide applied before the corn or soybean plants emerge from the ground.

As for Hood, his proof is in walking through the clean fields, he said.

If you do want to try a new additive, Hager recommends trying it first on a portion of a farm, rather than on all the acres the first time.

To see more of The News-Gazette, or to subscribe to the newspaper, go to

Source: Knight Ridder/Tribune Business News