Re: earthworm castings

Paul Krombholz wrote, 28 Oct
> Subject: Re: earthworm castings
> Anne Seales wrote, Oct. 27:
> >.......Their worm castings are available in 1/2 cubic foot size @$9.95, and 1cf
> >@$15.95.  Shipping is steep as this stuff is heavy - add $5 per 1/2cf bag,
> >and $10 per 1cf bag.  .......
> Before you shell out all those $$ for earthworm castings, are you sure that
> there is anything special or magical about earthworm castings?  What is in
> earthworm castings that isn't in ordinary topsoil that would befefit
> aquatic plants?  Please, whoever sets up some plants with earthworm
> castings, do an experiment for us.  Set up one tray with castings and
> another with ordinary topsoil, and plant the same kind of plants in both
> trays.  Let us know if there is a noticeable difference in growth between
> the two trays.

I don't think we will find a really big difference between good quality
black loam and earthworm derived humus aside from higher proportions of
sand or clay in the former which may not matter. Sometimes it's just
hard to find black loam. The dirt available here in Vancouver is pretty
sandy or clay with low humus. That's why I didn't use it.

The point of using earthworm castings is to provide a high quality,
fully composted humus. It would be useful for Aponogetons, Ludwigia
and other species which tolerate a rich substrate. If used in moderation
it would also do well for a general purpose substrate and would be very
similar to plain dirt or topsoil. It has the (possible) advantage over
potting soil in that it does not contain uncomposted organics such as
peat. Of course, Neil Frank is using a peat and vermiculite substrate with
good success. Neil, is that substrate designed for a specific type of
plants or kind of general purpose? What was the composition again? I
also recall you mentioning that mud substrates are very commonly used
by the academic types for research on aquatic plants. In your opinion,
are these soil based substrates trickier? Karen, are Crypts generally
lovers of rich, muddy substrates too?