Muriate of Potash warning

[dice]

A warning on using fertilizers containing muriate of potash
(potassium chloride) as potassium source:

As for your low-Potassium predicament, I have a warning
for you: Under no circumstances should you EVER add Potassium
Chloride to boost your K. That stuff will kill every Earthworm down
there; there goes your Humic Acids. It's also called Muriate of
Potash. Use Greensand or Wood Ashes instead.

Quoted from
http://en.allexperts.com/q/Fertilize...-Vegetable.htm

(I don't know the expert, I don't have independent confirmation
of the toxicity to earthworms, but there are plenty of
alternate sources of potassium for incorporating into soil
or container mix.)