Blasting those blasted weeds

By Carol Stender
cstender@agrinews.com

Date Modified: 05/21/2012 1:48 PM

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MORRIS, Minn. — Organic farmers want to blast one of their greatest production challenges —weeds. They may be getting that chance thanks to Frank Forcella's latest research project.

Forcella, weed scientist at the USDA-ARS Soils Lab in Morris, is studying the effects of "sandblasting" abrasive grit on in-row weeds.

Graduate student Corey Lanoue and professor Dan Humburg, both of South Dakota State University's Ag and Biosystems Engineering Department, have built a sandblasting machine for field use. The unit has four nozzles under grit tanks that blasts young weeds.

Forcella has jerry-rigged a smaller unit in the Soils Lab's greenhouse, where he's studied the affect on weeds and plants.

Blasting didn't hurt corn plants when applied twice at the one- and five-leaf stage, he said. Last year they researched its impact on soybeans when applied at the cotyledon leaf stage.

Forcella's weed blasting idea got its start due to an abundant apricot crop in 2007. Forcella enjoyed processing the fruit, but was left with a five gallon pail of pits. He wanted to find a use for the pits. Google searching apricots, he found a link to sandblasting. It spurred the weed scientist to consider pits as a sandblasting material.

Organic growers were enthused when Forcella broached the possibilities with them.

Apricot pits may not be a feasible and sustainable choice for grit in Minnesota. Ground corn cobs would work well, he said.

Sandblasting weeds may not be economical as the only weed control measure, Forcella said. A combination of sandblasting for in-row control and flaming for row weeds may be good.

The lab is also testing cover crops in the weed management system. A cover of winter rye is planted in the fall and, when it heads in the spring, is killed with a roller-crimper. The grain is seeded into the two-inch mulch, which also suppresses weeds in the row.

Forcella recently returned from a month-long research project in Spain where vineyards face the same in-row weed issues. The sandblasting machine will need some renovations for vineyards, but the principle is sound.

The researchers hope to field test the sandblasting unit in two to three weeks, Forcella said.