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Barley Straw revisited
Hi people,
I have lurking for over two years now and so I thought that I should
finally contribute something to the list. This is the first time I am
posting, so be nice.
The previous mails regarding barley straw has lead me to believe that the
algae control by barley straw was largely due to the release of hydrogen
peroxide and super oxide radicals, under aerobic conditions with bright
light. After that, we see many people dumping hydrogen peroxide into their
tanks.
Since then, someone directed me to this paper by N.C. Everall and D.R.
Lees, 1997 (The Identification and Significance of Chemicals Released from
Decomposing Barley Straw During Reservoir Algae Control, Wat. Res., Vol 31,
No3, pp 614-620) and it suggests that the anti-algae properties of barley
straw was attributed to a cocktail of phenolic compounds which are of known
phytoplankton toxicity, and some, are toxic to higher plants. This also
includes some unknown chemicals that are yet to be identified. He goes on
to described lignin as a promising source of "anti-algal precursory
oxidized phenolics" and suggested that you could use other alternatives (he
cited anti-algal studies done on oak leaves). Also, "Phototransformation of
phenolics results in the biproduction of potentially phytotoxic hydrogen
peroxide and super oxide radicals".
In an earlier paper by the same person, he stated that barley straw was
used because of a low phosphorous content.
Addressing the issue of Dulpa and their fermenting straw in dark reactor:
Since the anti-algal properties are due to phenolic that solubilize from
barley straw, it doesn't really matter what material the reactor is made
of. Dupla used dark plastic because decomposing barley straw is probably
not a pretty sight in a well- planted Dutch tank. In anyway, I suppose you
can throw a bale of barley straw in your sump and have the same effect as
Dupla's reactor.
Also, since the paper that I've cited is dated 1997, I was wondering if
anyone else to update on this.
ck