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Re: Steve's nutrient method (derived from Krombholz)

Kevin M. Hanson wrote:
> >Date: Sat, 13 Dec 1997 04:54:18 -0800
> >From: Stephen Pushak <teban at powersonic_bc.ca>
> >Subject: Steve's nutrient method (derived from Krombholz)
> >
> >Step 6) prepare a mixture of Krombholz soil soup (mix with water to form
> soupy mud)
> Can you help me find more info on what "Krombholz soil soup" is?  I am very
> interested in your nutrient method, but I am not familiar with this
> reference.

Here is some information from a discussion in June of 96 between several
folks on the subject of soils and substrates. This comment is from Paul
Krombholz and describes the "soil-soup" method along with some other
comments. I looked for an entry in the index of TAG back issues but
didn't find it. Paul may be referring to his article in TAG 9:3, "Part 4
Homemade Nutrient Solutions" where he describes extracting powerful
nutrient solutions from soil and compost. Maybe he can give us another
reference on soil-soup.

"Steve, June 13, expressed concern about high concentrations of
nutrients released by composting. I am concerned about that. too,  I
don't think it is good to have high concentrations of soluble nutrients
in the soil of aquatic plants.  In theory they can cause osmotic damage
to the roots of aquatic plants, and nitrates in the soil can prevent, at
least until they are used up, the desirable reducing conditions that
make iron soluble.  Besides,  the nitrates are wasted if they get
converted to atmospheric nitrogen.   If I have soil that I think has a
lot of nutrients released by composting, I extract the nutrients before
using the soil for growing aquatic plants. The latest TAG describes two
methods I use to extract nutrients from soil. Just ordinary soil from
the woods shouldn't need to be extracted.  it is already thoroughly
extracted by the rains and the plant roots.  I shouldn't think that
there would be any need to extract composted soil-peat mixes because
there are such small amounts of mineral nutrients in peat.  It might be
advisable to extract soil-manure mixes before use.  I think that, for
beginners, soil-peat mixtures would be 'safer'.

"The "soil-soup" method where soil is collected and water is slowly
added with much mixing until you have something like thick soup, which
is then run through window screening or a rice strainer, produces a safe
product. The screening filters out all the roots, worms and other
critters, and other "raw" pieces of organic matter that might cause a
large oxygen demand.  About a quarter inch to a half inch of the soup is
placed in the bottom of the tank or planting tray and covered with about
a half to one inch of gravel.  Water can be added with precautions to
prevent stirring up the gravel, and almost no cloudiness will develop. 
The gravel can be put on top of the soup, and then everything can be
allowed to dry out.  The soup turns quite hard, but when water is added,
it gets soft again, and the plants seem to grow just as well.  If the
soup has been allowed to dry out, the chances of any cloudiness
developing when water is added are much less. The soup is relatively low
in organic matter, and I have found that, when a tray becomes packed
with roots, low-level iron deficiency develops, and additions of soluble
iron stimulate growth.  Soil-peat mixtures or soil-manure mixtures
beneath gravel seem to be able to supply iron for a longer time.  I have
not seen any tannins come from soil-soup, but I have seen tannins get
into the water from soil-manure and soil-peat mixtures.  A water change
gets rid of them, and they don't seem to come back."

Note: I'm not advocating beginners to try things like manure or compost!
Caution!!! :-D