Skip to content

Brainstorming a Better Tarp

They mushroom every fall — great domes of grain covered with immense sheets of plastic. Millions of bushels of newly-harvested corn, soybeans and wheat are stored outdoors at elevators all over the Midwest, an emblem of modern agriculture’s stunning bounty — but also a major vexation.

“Every fall we have to put tarps on our grain piles,” says Doug Kavanagh, operations manager at Glacial Plains Cooperative in Murdock, Minn., which handles more than 20 million bushels of corn a year. “Every co-op does. It’s a very common practice.”

But covering a two-million-bushel corn pile with a 200 x 400-foot plastic tarp is an expensive, back-breaking job. It takes eight or 10 brawny men an entire day of slogging over the slippery hill of grain, lugging a four-ton, $40,000 tarp into place. Then the seams have to be taped and the edges secured. The weather during this operation is often cold and windy, adding to the misery and danger.

Once the tarp is in place, aeration fans must run continually to keep the cover from blowing off. Tarps often tear, letting in moisture. And when it’s time to move the grain in the spring, the single-use tarps have to be cut up and hauled to a landfill. It all adds up to a boatload of labor, expense and hassle.

A couple of years ago, after a day of tarp wrangling, Kavanagh woke up in the middle of the night and thought, “There has to be a better way — maybe a spray-on cover.” He mentioned his 3 a.m. brainstorm to Tom Traen, Glacial Plains general manager. “Tom said, ‘That’s a good idea, and I know who to call for help!’ ”

Kavanagh and Traen sat down with Michael Sparby, AURI project director, and AURI chemists Doug Root and Ranae Jorgenson to hash out the concept. That was the genesis of an ag-based, sprayable “bio-tarp,” designed to shed water and protect grain and silage piles all winter.

“We recognized an exciting idea,” Root says. Although spray-on organic coverings are used in other settings, such as waste lagoons and sugar beet piles, “there doesn’t seem to be anything like this onthe market.”

The patent-pending product, called “E-Z-Tarp,” was formulated and bench-tested at AURI’s fats and oils lab in Marshall, followed by small-scale trials at the Murdock co-op. Now it’s ready for commercial scale-up and final testing. Kavanagh and Traen, both grain-industry veterans, are seeking investors.

Development by trial and error

It took about two years to develop the E-Z-Tarp formula, says Ranae Jorgenson, AURI analytic chemist. The product had to be made of 100 percent food-grade materials. It had to form a waterproof barrier durable enough to last through the winter without cracking, yet crumbly enough to mix easily into the grain or silage pile after storage. Finally, it had to be sprayable in cold weather using existing mixing and application equipment.

The first two bio-tarp formulations failed in outdoor tests. The third formula was tested on small corn and haylage piles during the fall and winter of 2009-2010. “It held together all winter,” Kavanagh says. The corn piles remained dry, and periodic aeration didn’t disturb the covering, he says. The haylage piles “continued to ferment under the bio-tarp, just as they were supposed to do,” he says.

“We think we’re pretty close to the final formula,” Jorgenson says. The next steps will be testing the bio-tarp on commercial-size grain piles and identifying the most efficient mixing, pumping and spraying equipment. The material, a water-based emulsion like latex paint, has a syrupy consistency. The bio-tarp ingredients are mixed and heated to 140 degrees, then pumped while still warm. As the emulsion cools, it hardens into a solid waxy sheet, creating a waterproof cover in about four hours.

The optimum application rate also needs to be refined, Jorgenson says. Three application rates were tested in 2009-2010. A layer 1/8 to 2/8 inches thick appeared to work the best, Kavanagh says, but that needs to be confirmed in trials on larger piles.

Kavanagh and Traen have invested considerable time and money in E-Z-Tarp, much of it to obtain a patent. “We expect that it will take about $100,000 to scale up and finish testing,” Kavanagh says. They’ve identified a Wisconsin dairy producer who is interested in trying the bio-tarp on silage piles. The two grain merchants are looking for an equity partner to help them complete testing this fall and bring the bio-tarp to market.

Better performance, labor savings

E-Z-Tarp offers both performance and economic advantages over standard polyethylene covers, Kavanagh and Traen say.

Plastic tarps rely on the suction created by aeration to hold the cover against the grain pile. When power outages take the fans off line, tarps can lift up and rip or blow away. “We’ve had that experience quite a few times,” Kavanagh says. With the E-Z-Tarp, by contrast, “if there’s a power outage, you still have protection.”

The bio-tarp also lets you run aeration only as needed, rather than continuously, saving energy dollars, he says. In addition, the undisturbed parts of the pile will remain covered as grain is picked up, unlike plastic tarps, which are generally removed all at once, leaving the pile open to rain or snow during loading.

“I see this as a huge advance in preserving the quality of commodities,” Traen says.

But the biggest advantage of E-Z-Tarp is labor savings, Kavanagh says. Installation will take just a couple of operators and require none of the heavy lifting that can lead to worker injuries. An application rig — similar, perhaps, to a small fire ladder truck — would be used to spray grain piles. Kavanagh envisions a custom service that would travel around to elevators and livestock farms in the fall.

E-Z-Tarp would also eliminate tarp disposal costs, Kavanagh says. Instead of paying 5 cents a pound to landfill the plastic every year, “you could actually get paid for the bio-tarp.” That’s because grain may contain up to three percent foreign matter, so the bio-tarp could simply be incorporated into the final product after storage. “It’s all food-grade and would be minimal in weight,” Kavanagh says. For livestock producers, the bio-tarp ingredients “would increase the feed value,” he adds.



AURI and E-Z-Tarp

AURI scientists Ranae Jorgenson and Doug Root worked with two grain marketing veterans to develop a new covering for grain stored outdoors.

 Idea to opportunity

Develop a spray-on biodegradable, food-grade covering for grain and silage piles, replacing plastic tarps.


Prototype successfully developed and tested at AURI’s Marshall laboratory; being tested this summer on large scale.