I am hoping Kelley will see this post. If I were to guess, I would think that vermicompost just might be more biologically active than castings.

Hmmm. I would definitely disagree with the definition provided. Worm castings are simply the manure of the earthworm. Whether or not they've been re-ingested and how many times is irrelevant. The definition provided by ebfarm.com is not based on any scientific data with which I am familiar and is not accurate.

As to nutrients being depleted by re-ingestion, this statement is, again, not based in scientific data and suggests a lack of understanding of nutrient processing in the worm gut.

There are differences between pure worm castings and vermicompost (which is defined as the finished, unscreened output of a worm bin, comprised of castings, decomposed OM that did not pass through the gut of the worms, and partially decomposed OM), but it is innacurate to suggest that one is necessarily better than the other. Pure castings tend to be higher in plant growth regulators and soluble nutrient than does vermicompost, but vermicompost TENDS (this word is important to remember!) to demonstrate better disease suppression, a more broadly beneficial impact on moisture management in soil systems to which it is applied, contain more organic matter, and support a more diverse cross section of microbial species. While I tend to recommend vermicompost more often than I do castings, this is more for practicality than because vermicompost is generally speaking a "better" product.

Does that make sense?

KellyS

How do you know if you've got vermicompost or castings? The last time I harvested, the stuff was crumbly and almost black with no recognizable OM in it, not even shreds of paper or eggshells. There were some worms still cavorting around in it. The "crumbs" were about 1/4" in diameter and moist. Castings? Vermicompost?

As I understand "castings" are just that.."castings". Castings are the very finished material of the OM. Vermicompost is the composted/partially composted OM.