The scoop on manure

Cow manure labelA friend of mine recently asked me about manure. In a nice way. And it got me thinking. And doing a little research. And what I gathered will raise some eyebrows.

But first, I’ll back up a bit. She asked me about manure because she knew I’m in the middle of taking the Organic Horticulture Specialist course offered by Humber College. When people ask me about it, I tell them the short story is that I’m studying dirt. Never in all my life did I think I was going to spend hours and hours pouring over textbooks, lesson notes and videos, all about the nature of soil. And never did I think I would fall in love with the stuff. But here I am and I have. Check out the video below to get a taste of what this course is about.

Anyhoo, my friend wanted to know if buying manure (the kind you get in plastic bags at the garden centre, not from a steaming pile at the farm) was an organic option for gardeners. You know, organic as in a good-for-your-garden way. This seemed like a straightforward question but, being halfway through my course, I knew at least enough to hesitate and admit I didn’t have a clue about whether that stuff was organic. What I have learned so far is that a lot of fertilizers and other soil amendments are promoted as good for your soil and really, really aren’t.

So I went to a couple of garden centres and took some cellphone snaps of the ingredients lists on some different packaged manure options. I found bags emblazoned with “Cow Manure” and I also found bags saying “Cow Manure” in big letters and, in much smaller letters, the word “compost”. Then I did a little digging. Here’s the poop. (Sorry. Couldn’t resist.)

The label may say manure, but…. On one bag, the ingredients list included the expected nitrogen, phosphorus and potassium, each at a guaranteed minimum amount of .5%. Maximum Moisture was listed at 60%. OK. Ya don’t want manure that’s the consistency of dried cement. Here’s the eye-opener: Organic Matter was listed at 25%. Sooooo, what’s the other 13.5%? We don’t know. Another brand listed Organic Matter at 50% and Maximum Moisture at 60%. More hmmmmm-ing.

BTW, in the first lesson of my course, we learn that “organic based” fertilizers legally only need to contain 15% organic matter. The other 85% can be synthetic. Also, “organic matter” is composed of decomposed plants and organisms and their waste products. So I couldn’t tell from the ingredients lists I looked at just how much cow manure was really inside the bag. There could have been a lot of other stuff.

The bag should state that it is pathogen-free. Yes, kids, yucky stuff can get through to you and your garden if the manure is not composted properly. However, even if the composting process used was correct by all industry standards, certain other things besides pathogens can still get through and into your bag of cow manure. These include heavy metals. According to Heide Hermary, author of Working With Nature, the textbook for my course, other problems with using manure as feedstock for compost include the fact that farm animals are regularly dewormed and that the dewormer can make an impact on your garden’s earthworms. And they’re the good guys!

And then there’s arsenic and pesticides. Yup. This is something else I learned from Ms. Hermary. Chicken manure can have high levels of arsenic. Mushroom manure can include the pesticides originally sprayed on the mushrooms. And then there’s the whole GMO issue.

Plants are better than poop. Here’s the bottom line as taught in my course. Raw manure is the end product (snicker) you get when an animal eats some plants and takes all the nutrients it needs from them first. So you’re left with semi-nutritious material. Why not just go with a much more efficient source? Leaf mulch and plant-based compost can offer more nutrition to your garden plants.

Is packaged manure or manure compost that you get at the store organic? If the ingredients list includes organic matter, well, you’ve got organic matter. But, if you want organic in the good-for-organic-gardening sense then, no, not unless the package distinctly says “certified organic” on the package.

One thought on “The scoop on manure

  1. Pingback: Is your soil healthy? More dirt on dirt. | Rhymes with Linnaeus

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