For organic growers, weed control can require much time, effort, and creativity. They must find cost-effective ways to prevent weeds from reducing crop yields without using chemical herbicides. A new technique — sandblasting — was recently tested on crops of field corn.

The current issue of the journal Weed Technology discusses tests conducted on six plantings of field corn over two years. The tests sought to discover if applications of corncob grit propelled by compressed air could be an effective form of weed control.

Sandblasting is typically a technique used to remove paint or rust from a metal surface. By using a “soft” grit that is also a natural material, such as corncob residue or nut shells, this technique can be used agriculturally. These additional uses for agricultural residue could also increase the value of the parent crop.

When sandblasting weeds, grit from a compressed air tank is aimed at the weeds growing near the bases of corn plants. To determine at what point in the crop cycle this weed control was most effective, sandblasting was performed from the one- to five-leaf stages of corn growth. Some test crops received second and third treatments of abrasion.

The corn plants were unaffected by the procedure, while the weeds were eliminated with varying degrees of success. This research found that multiple sandblasting at the one- and five-leaf or the one-, three-, and five-leaf stages produced consistently high levels of weed control throughout the growing season. Single applications or multiple applications of grit at other times in the growth cycle did not produce satisfactory results.

While sandblasting proved to be a viable technique for weed control, this experiment did not prove it to be a cost-effective one. Expenditures could be reduced, however, if a farm were to collect and mill its own corncobs rather than purchasing grit. Another option might be to substitute an organic fertilizer, such as seed meal or crushed limestone, as the grit, thereby achieving two purposes at once.

Full text of the article, “Air-Propelled Abrasive Grit for Postemergence In-Row Weed Control in Field Corn,” Weed Technology, Vol. 26, No. 1, 2012, is available at http://wssajournals.org.