Chemistry 101. Potassium chloride. Was: Muriate of Potash

J.E. Shields
Tue, 08 Nov 2005 09:29:20 PST
Hi all,

Roger and Arnold have provided some excellent information on this subject.

What distinguishes potassium chloride from potassium sulfate is chemical 
composition, and the relative biological effects of the chloride vs the 
sulfate ions.  Both are soluble sources of potassium.  Industrial grades of 
either may contain traces of other materials.

Chloride is the combined form of the element chlorine, and it is essential 
to most living things, but in limited amounts.  Higher levels of it are 
toxic, and what those levels are specifically depends on the species of 
plant under discussion.  "Muriate" is an archaic term for chloride and is 
not used in the modern scientific literature.  You can look it up in any 
good dictionary of the English language.  Just as we avoid vernacular names 
for plants, we would also do well to avoid using them for chemicals.

Sulfate provides the element sulfur, which is also essential for all living 
things.  It occurs in proteins as the amino acids methionine and 
cysteine.  It can play a role in the transfer of methyl groups in 
biosynthetic processes.

Potassium chloride is cheaper than potassium sulfate or potassium 
phosphate, and is likely to be found in cheap fertilizers as a source of 
the element potassium.  It isn't advisable to use any fertilizer containing 
chloride on plants that have any sensitivity to chlorine.  More expensive, 
higher quality fertilizers will not contain much chloride.

Jim Shields
AB in chemistry
PhD in biochemistry

Jim Shields             USDA Zone 5             Shields Gardens, Ltd.
P.O. Box 92              WWW:
Westfield, Indiana 46074, USA
Tel. ++1-317-867-3344     or      toll-free 1-866-449-3344 in USA

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