organic

There seems to be a lot of this going around lately, generally amongst the hard science fellas & gals, which brought a thought to my mind about worm castings.

Those of us into the organic thang all swear by their usefulness, but I have to call in to question one of their oft-stated benefits - i.e., the supposed presence of trace elements.

In compost science circles (particularly the simmering cauldron of controversy surrounding compost teas) some of the basic assumptions about compost formulation are being re-examined. To this end, considerable examination is being made of the nutrient composition of feedstocks as it relates to the benefits of the finished product.

Good lord, to think that I was once an english major. I can't even understand what I just wrote. Anyway, in plain language, what I'm saying is that a finished composted product is pretty much not going to contain anything - at least nutrient-wise - that the feedstock it was decomposed from did not. In other words, if you use rabbit poop with a NPK of 2.4-1.4-0.6 as the major constituent of your compost feedstock, you're not going to get any more than 2.4-1.4-0.6 in your finished compost, and probably less.

How does this relate to worm castings? Well, it's assumed that all worm castings contain trace elements/micronutrients. But if there are no micros in the feedstock that the worms were consuming, I am guessing that it's fair to say that the worms won't be producing micros from inside their guts. They produce lots of interesting things in their poop, but nutes aren't one of them AFAIK. End result, those of us relying on worm castings as our sole source of micronutes might very well be shortchanging our ladies.

Just a thought...questions, comments?

O

3hounds

I think the worm castings question is a valid one simply because we know nothing about the conditions under which they are produced.
Worms fed a rich diet of all things good and proper might be one thing, while commercially "grown" castings are likely fed the most economical food on which they will survive (vs."thrive").

The manufacturers conditions might be interesting to investigate... according to http://www.wormdigest.org the large farms feed the worms "cardboard paper sludge". If this is normal practice, and I have no reason to believe that is not, then how can that provide optimum nutrition?

As with human diets, perhaps variety is the key to well rounded nutrition?

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organic

Good point 3H. I do know of a local company who produces castings, and they feed theirs dairy manure which is an abundant waste product in my area. This would seem to be a more nutritious feedstock than cardboard sludge (although surprisingly I've heard reasonably good things about the finished product from that), but even manure alone seems to me to be a bit lacking.

I did come across a short research paper once comparing the nutrient levels of castings based on different feedstocks and the finished results showed wide variation. It didn't address the subject of trace elements however...I am wondering where this (probable) myth began.