Many different conclusions on comfrey.

I had hoped to find facts on comfrey but I found confusion and more questions. I should be fairly simple. You take different plants from different areas and study them in all useable forms. Chop and drop mulch, tea and maybe even a dried soil amendment. I would guess that my NC farm would have different characteristics than someone’s from Montana. Maybe not drastic differences though.
I spent last evening trying to find results that weren’t all over the board. The garden myths website says it’s no better than any other plant. He did concede that it was a great plant to help bulk up compost. Another graphic showed it had no available nitrogen, (which I do not believe) but did have minor nutrients other than NPK. There are other examples that all blended together into vastly different, forgettable mix.
Does anyone have something definitive?

From Toby Hemenway's "Gaia's Garden" page 132 dynamic accumulator table.  Comfrey accumulates nitrogen, potassium, calcium, magnesium, iron and silicon.  


A 2010 comfrey fact sheet  There is good nutrient tables in the article.

"Comfrey  provides  a  low  fibre,  high  protein  and  high  mineral  feed  which  can  effectively  replace  some  costly  concentrates in the poultry diet.
The protein : fibre ratio of comfrey is around 1.5:1.0 as against young lucernes which run around 1.0:1.5. The additional vitamin A provided by comfrey can cause a yellowing of the flesh in meat birds, similar to the premium ‘corn fed’ birds available commercially. "


I try to search from just .org and .edu sites for data related inquiries.  The search terms I used to find the comfrey info sheet was "comfrey leaf protein content"  I also saw some good links searching "comfrey leaf nutritional assays"  Google search algorithms sometimes need help to tease out useful links.  I try to think of using odd and unusual words to expand the search area.  Almost like playing the game scattergories.  


I would also like to note its role as a bee and insect attractant.   Insane amounts of flying bugs and bees visit my comfrey plants.  

You’re the best Brian! I bought Gaia’s garden years ago and made the mistake of loaning it out. When I looked it up I was looking for calcium mainly. Then it got weird. Regardless of what I read I have comfrey and will continue to use it. It just irritated me that there were so many sites with so many different analyses. I’d like to have my own analyzed to see what’s going on here on the farm.

Random websites (even with good .org or .edu credentials) can include all sorts of opinions based on not-truly-solid research. To find good peer-reviewed research, the best method that’s available to almost all of us (without access to a university library) is scholar.google.com

Google Scholar is far from perfect, and not as comprehensive as a massive university library, but it’s very good.

And post the results here!  Always interested in actual facts about comfrey!

So true Anne. I managed to get a screenshot of many different plants from a university. I’m posting a cropped picture of the NPK. Zero nitrogen!?!?! Even regular grass has nitrogen.
I have a garden bed with comfrey in the middle. After planting tomatoes today I chopped the comfrey to the ground and mulched around the plants. I will do this at minimum monthly until November or so. I have my other plants on the edge of planting spaces. I like to be able to mow it with my bagger on and mulch with that.

Even the concept of a "dynamic accumulator" is unproven.  I'd like to believe that it's true --- that certain plants send a deep tap root down into the soil and mine the subsoil for scarce nutrients, which they then draw up to the soil surface where they are deposited when the comfrey leaves are picked/eaten/composted.  In theory, it sounds right.  But as far as I know, there has never been any peer reviewed research that clearly proves that this is, in fact, taking place.  

Testing it should be fairly straight-forward: take two identical plots and test the soil to get a map of the nutrient composition of each.  Then plant a bunch of comfrey in the one, while leaving the other bare as your control group.  After a few years of chop-and-drop composting, test the soil once again.  Is the comfrey actually delivering sub-soil nutrients to the surface?

I personally like comfrey because: 1) the chickens can't kill it.  They eat it but it's indestructable.  2) it's a great compost activator.  If you've got a cold pile, nothing heats it up faster than comfrey.  For this reason alone, I'd have to think that it's got a lot of nitrogen.  3). I like how comfrey quickly fills in a bare patch under a tree or in a hard-to-grow space.

"I'd like to believe that it's true --- that certain plants send a deep tap root down into the soil and mine the subsoil for scarce nutrients, which they then draw up to the soil surface where they are deposited when the comfrey leaves are picked/eaten/composted. "

I don't know how it could possibly be untrue, Marco. Clearly plant roots will absorb mineral nutrients from as deep as their roots go, and if those minerals are transported to the above ground foliage they will.become part of.the surface biome. We may fail to acknowledge just how many minerals are used in root development and thus overestimate this effect when we imagine that all the minerals obtained 6 ft deep end up in the leaves, but I am under the impression that the only question about dynamic accumulators is whether particular plants actually do an exceptional job accumulating a particular mineral or not.

As for comfrey and nitrogen, all I need to see are those giant dark green leaves growing profusely to know that there is plenty of nitrogen in that plant