Understanding Corn Gluten Meal Vs. Corn Meal
What Is the Difference Between Corn Meal & Corn Gluten Meal? That’s a most common question these days as the interest in alternative weed controls continues to dominate the organic lawn care banter. Here’s an overview of the two distinctly different products:
Both corn meal and corn gluten meal originate in the same place, with whole kernels of corn. Corn meal, the same stuff we use as a coating for food, is simply ground up corn. Corn gluten meal is a bi-product — and the two products, in general, cannot be substituted for one another. Depending on how they are milled, however, they can appear almost identical.
Corn Meal — Most corn meal is made from grain corn intended for animal feed, but Purdue University in Indiana told us that 10 percent of grain corn is used for corn flakes and other edible products. Our friend, Howard Garrett, aka “The Dirt Doctor,” has long espoused the virtues of corn meal as a fungicide on the lawn — or for feet for that matter. We’ve never used it for that purpose, and several universities dispute the claim, but we’ve always found Howard to be a credible authority.
One thing corn meal won’t do is suppress weeds and it’s also not particularly useful as a fertilizer, although some value is obtained.
Corn Gluten Meal — This is derived from the part of the kernel that doesn’t get used in corn meal. It’s high in protein and nitrogen, which makes it an excellent lawn fertilizer, but is not really edible — although it won’t hurt you if you swallow some. I’ve gulped handfuls of the stuff at my public speeches just to make a point about safety.
In the mid 1980s professor Nick Christians at Iowa State discovered that corn gluten meal truncated the growth of young seedlings. The oily coating on the corn gluten meal doesn’t allow plant roots to form and the recently geminated seedlings die. A lot of conditions have to be perfect for this phenomenon to occur, however, and as we’ve posted here for the past two years, corn gluten meal is not considered a highly practical weed control tool — especially given the price increases of the past five years.
A Note About Genetic Modification — The use of corn gluten meal in weed control is allowed in many organic standards programs, including our SafeLawns Approved program, although the corn gluten meal is not technically organic because most corn is genetically modified by Monsanto and others to resist Roundup or Bt. Organic sources of corn gluten meal do not appear to be readily available, although we’d be happy to post any sources here if anyone knows of such a thing.