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View Full Version : Polyhydroxycarboxylic Acid: Good or Bad?


DavidNJ
12-22-2010, 06:24 PM
Polyhydroxycarboxylic Acid? Also called PHCA, it is an organic compound added to lime. At least three different products have it: Solu-Cal, Verde Cal, and OldCastle's Cal-Turf Pro. All have 30-37% calcium and 2% polyhydroxycarboxylic acid.

All claim to effectively alter pH in 1-2 months, much faster than a normal lime application, and improve plant absorption. They all claim a maximum application rate of 12lb/Msqft. None talk about how the effectiveness is effected by different buffer pH ratings. None discuss the science objectively. None talk about why their effectiveness is claimed to be 4x what their CCE (calcium carbonate equivalent) would indicate.

Are there any reports or papers that discuss the science behind it and how to calculate application rates? The number of different products and their fairly wide distribution seem to indicate it works. The claims to more rapid effectiveness would indicate it would be very useful when an immediate correction is needed for a new lawn, rennovation, or overseeding.

Sidebar: Cal-Turf Pro indicates they have an encapsulation in of the calcium in the PHCA causing more effective distribution. Do the other brands do that?

RigglePLC
12-22-2010, 08:59 PM
An organic complexing agent. I could not find much more.
http://www.brettyoung.ca/Western_Canada/Products/Turf/documents/Soil_Amendments_2010.pdf

DavidNJ
12-23-2010, 03:01 AM
This is challenging my knowledge of chemistry. It seems to be tied to the Cation Exchange Capacity and Chelation in which organic acids bond with metals making the insoluable and non-reactive. But then the question arises why aren't these amendments more common and done without a lime component? I did find one fertilizer, Wilbur-Ellis Foli-Gro CarboCal that includes it; 6% nitrogen, 8% calcium (from calcium nitrate) and 3% polyhydroxycarboxylic acids. It is a 6-0-0 spray.