They began in the south, and slowly, stealthily, they’re creeping up north. And they’re getting stronger by the minute. We’re talking about weeds. Weeds, the dread of every farmer – especially for organic farms, like the one NDSU student Paul Subart currently works on in North Dakota. It was weeds that inspired him late last July, as he sat atop a tractor mowing down weed patches on a flax field.

“I knew there had to be another way to control them without mowing or digging,” he said.

There on that tractor, he envisioned the preliminary designs for a modified rotary hammer mill; a design that he has now polished, presented at the NDSU Innovation Challenge, and that won first place in the Corn Track of the competition. Now he not only has the design and support from local farmers, but $5,000 in awards money to begin building the prototype.

Modified Rotary Hammer Mill

The Subart Farm

Enter the hammer mill weed-pulverizer

What Subart has designed is a modified rotary hammer mill which, when mounted on the back of a combine, is able to pulverize weed seed in a way that the organic matter is saved and returned, he said. This not only reduces the amount of weeds but also improves overall soil quality, he said.

“It reduces weed pressure, reduces the amount of viable weeds in the soil, so that the herbicide has a better chance of success,” he said. “Then you have less weeds in your field, which is something every farmer wants. It creates an all around more sustainable farm.”

Subart, a 21-year-old junior at NDSU studying Crop and Weed Science with a soil science minor, said the process of the project, named “A Displaced Farmer,” took a lot of designing and re-designing over the past months.

“I was thinking of [the project] when I should’ve been taking notes in class,” he said with a laugh.

Dan Hieserich, Mill Training Coordinator at Cargill Corn Milling and one of the judges for the Innovation Challenge Corn Track, said he and the other judges saw high potential for Subart’s design.

“Paul’s innovation has the potential to have a very high impact in the organic farming industry and possibly to the farming industry as a whole,” he said. “If his device can prove to reduce weed pressure without the use of chemicals, input costs for farmers as a whole could be reduced.”

The war of the weeds

Subart knows first hand the annoyance of weeds; he grew up on a family ranch, and has spent the past five years working at an organic farm.

“All you do is dig,” Subart said. “This mill would be a huge for organic farms, especially.”

As weeds continue to grow more resistant to herbicide, particularly against widely used herbicides like Roundup, the need for stronger battle techniques is becoming a “rather dire need,” he said.

In particular, a certain weed named The Palmer Amaranth, also called “The Terminator” or “Satan,” has won Weed of the Year the past two years for being the most herbicide-resistant weed – and it’s coming. It is currently working its way up the corn belt, Subart said – and though it hasn’t hit North Dakota yet, weed experts are saying it’s only a matter of time.

The only known solution down south, Subart said, is through tilling, hand-pulling, and combining herbicides. And that’s just no fun.

“My end goal with this mill, is to reduce the need for tillage,” Subart said. “To completely reduce the need for tillage in organic and conventional farms.”


The only competition for Subart’s design is pull-type seed destructor from Australia, he said. But this mill is different from his own in a few ways. Firstly, it costs around 200K, and Subart wants his mill to be under 10K in raw materials.

Secondly, the Australian pull-type is more bulky, and less likely to be adopted in the United States where combines are not built for that kind of pull machinery.

“Other than that, there’s really nothing that exists in the U.S.,” he said.

Hammer mill

Paul Subart (second form the left) after winning first place in the Corn Track at the Innovation Challenge 2015.

Next steps for A Displaced Farmer

With his recently earned 5k from the Innovation Challenge, Subart hopes to begin building a prototype and get a patent for the design. Eventually he would like to see his design commercialized, and even better, be integrated into the design of combines from the get-go.

“I know a couple farmers already who said if they have a working model, they would like one,” he said. “Ideally it would be taken to large commercializers and incorporated into the combines into the assembly line.”

Your move, weeds!

Photos courtesy of Paul Subart and Haneys Photography.

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Marisa Jackels