Corn gluten meal

Corn gluten meal (CGM) is a byproduct of corn (maize) processing that has historically been used as an animal feed. It can also be used as an organic herbicide.

The word gluten here is inexact; there is no true gluten in corn, but simply corn proteins. The expression "corn gluten" is colloquial jargon that describes corn proteins that are neither gliadin nor glutenin. Only wheat, barley, and rye contain true gluten, which is formed by the interaction of gliadin and glutenin proteins.

In 1985, Dr. Nick Christians of Iowa State University discovered that CGM displayed pre-emergent herbicidal effects during a series of turf grass experiments. The use of corn gluten meal as an herbicide was patented in 1991, but, like many food-related substances used for gardening, is not regulated in the US.

CGM targets a range of plants include small-seeded annual and perennial herbs. It is most frequently used in lawns, but may be applied to gardens and fields as well. Large-seeded weeds seem unaffected.

The corn gluten meal breaks down over time as an organic nitrogen source (NPK rating of 10-0-0).

Proteins in CGM inhibit root formation on newly germinated seeds, killing the plant. Applications must be timed so that the CGM is present and effective as seeds are germinating.

Subsequent research has not been conclusive regarding the effectiveness of corn gluten as a preemergent.

CGM is applied using a spreader or even by hand: the material is essentially harmless if not inhaled, and is, in fact, edible (though not particularly palatable). On lawns, CGM is applied in early spring (usually timed phenologically by the blooming of crocus or forsythia), and again in the autumn. If the lawn is overseeded, CGM should either be applied at least six weeks before sowing, or two weeks afterwards.

Though very safe to use and nontoxic, CGM should not be applied to areas where it is likely to wash directly into watersheds (it is a nitrogen source). Otherwise it is ecologically safe.

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Wikipedia