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The USDA agronomist was confident he could find a use for the waste, and a few Internet searches revealed that fruit processors often crush the pits for use in sandblasters. That brings us to a less obvious question (but perhaps more obvious to weed scientists): Can you kill weeds with a sandblaster?

“It seemed like such a silly idea at first,” Fossella said. But he and colleague Dean Peterson of the U.S. Department of Agriculture’s North Central Soil Conservation Research Laboratory in Morris, Minn., are weighing the issue. “We ended up buying a cheap sandblaster and doing some simple experiments in a greenhouse.”

Their initial work involved growing weeds next to corn plants; when the corn was about six inches tall and the weeds were about one to three inches tall, the researchers destroyed both with sand.

It turned out that only the weeds were affected. In fact, the weeds were gone, but the corn plants were left untouched. This prompted a field trial in 2012, in which a larger sandblaster was mounted on an ATV. As Peterson drove, Fossella followed behind, crouched next to the blaster nozzle, blasting away weeds and other nuisance plants.

These early hand-held machines showed promise, if a bit of a chore for the people doing the blasting. But the researchers were excited by the results. So Fossella sought funding to develop a larger machine and began working with researchers, including Dan Hemberg, an agricultural engineering professor at South Dakota State University, who had the skills to build one.

Double treatment at the three- and five-leaf stage of corn allows achieving approximately 80% weed control throughout the season.

Forcella received a grant from the Foundation for Sustainable Agriculture Research and Education to develop a “pneumatic abrasive sand control system.” They began developing a sandblaster for weeding row crops like corn. The machine’s core component is the PAGMan, an air compressor that delivers compressed air to nozzles aimed at the plant’s roots. Crop residue is forced into the nozzle and sucked up by the fast-moving air. Almost any gritty waste (from seed meal to nut shells, fruit pits, and ground-up corn cob scraps) will work. (Forcella’s current favorite is granulated poultry manure: “We can weed and fertilize at the same time,” he says.) The PAGMan has four pairs of attachments that shred weeds up to two inches high but leave corn plants four inches tall or taller unharmed. Two applications (at the three- and five-leaf stage of corn) can provide about 80 percent weed control throughout the season, Forcella says. To demonstrate this, PAGMan will be field tested in corn and soybeans this summer in Minnesota and South Dakota.

The second model is the Veggie Blaster, run by Sam Wortman, an associate professor at the University of Nebraska. The machine is specifically designed for weeding, since the rows of vegetables are much wider. It is pulled behind a small tractor and moves between the rows of vegetables, killing weeds in the row. Vegetables such as tomatoes are typically grown on trellises covered in plastic. As weeds emerge from holes in the plastic for transplanting seedlings, sand is sprayed on them.

Wortman said they tested the Veggie Blaster on peppers, beans, edamame and zucchini this summer in Illinois. But since this is the first time the team is testing the Veggie Blaster this summer, they can’t yet say how well it kills weeds, he said.

Interest in the technique, known as “weed pulverizing,” is growing. A two-year field study at the University of Illinois’s Student Sustainability Farm found that the technology could reduce the need for tillage and hand weeding; and in Spain, a team at the University of Seville is developing a version of the Veggie Blaster that can detect the presence of weeds and activate only when needed.

“We don’t have patents on these devices,” Forcella said. “It would be very difficult to patent it, I wasn’t ready for that. So we more or less decided to go the open source route. We want to come up with a concept and test the idea. If it works, then hopefully some company will adopt it.”

It’s unclear whether equipment manufacturers will invest in the machines, although smaller components such as nozzle designs may be easier to patent. The main expense is the compressor: The PAGMan costs $9,000. Forcella estimates that retail units will cost at least $10,000.

On the other hand, a DIY setup for a small operation can cost as little as $1,000. Forcella said some versions of the weed-eating device may be patented in the future, but for now, the public can make their own. “Almost anyone can build a simple device.”

According to Forcella, California organic grower and Amigo agricultural consultant Bob Canistano built a vegetable sandblaster for less than $250. The entire process took about three hours. “It doesn’t require any special skills,” Canistano says, “just common sense.” He bought the sandblaster, walnut shell powder, fittings and hoses, made a “wand” out of PVC and brass fittings, and hooked it up to his portable electric air compressor. The device requires a power source to operate, but by mounting it on a cart along with a Honda gasoline generator, he can now pull it to a field or tree by hand, with a tractor or lawn mower.

While grass weeds require repeated applications because their growing point is underground, Canistano noted that the product is also effective against other weeds. “When used at the right time during the weed’s growth, this tool is very effective against most weeds, including broadleaf weeds, grass weeds, thistles, and gorse.”

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