8 Goes Green

Compost Study Shows Low Levels of Organic Matter in Samples

Posted: May 13, 2011 12:11 AM by Laura Hibbard
Updated: Jul 7, 2011 10:23 AM

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COLUMBIA - In a study by organic chemist Chris Cady the University of Missouri Soil Testing lab tested samples of ten different retail compost bags to determine their percentage of organic content. Cady said the inspiration for this study came from his own garden.

"Over the past few years I'd gone to some of out local stores and I've been finding these products where, if you look at a torn bag, just looks like it has a lot of soil in it."

Organic matter should be the primary ingredient of compost, but according to Cady before the tests were done, you only need to feel around in some retail composts bags to tell that this isn't really the case.

"This is a chunk of soil...it looks like silt," Cady said while sifting through a bag of store-brand compost. "This could really all be just be river bottom soil...there's a hunk of clay. That's a really good example of what we're talking about."

The results of the tests confirmed Cady's suspicions. The percentage of organic content in the bags ranged from 4.6 percent to 46.5 percent. According to Cady 4.6 percent is a good reading for topsoil products, but is extremely low for compost as it will not boost the organic material already in the soil. The top scores on organic matter went to the home made compost and Back to Nature Cotton Burr Compost.

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