Humic and Fulvic acid fertilizer testing and labeling, AAPFCO approved method.

Humic and Fulvic acid plant and soil amendments.

What are humic and fulvic acid?

The Association of American Plant Food Control Officials (AAPFCO) define them as follows:

Humic Substances – the major organic constituents of soil organic matter and the aquatic environment, consisting of complex heterogeneous mixtures of carbon-based substances formed by biochemical reactions during the decay and transformation of plant and microbial remains. They are primarily composed of three main fractions, called humic acids, fulvic acids, and humin, which are operationally defined by their solubility in dilute alkali and acid solutions. High concentrations of humic substances are commercially harvested from terrestrial deposits of Leonardite, oxidized lignite, oxidized sub-bituminous coals, humalite, carbonaceous shales, peat, and sapropel.

Humic Acids – the portions of the alkali extracted
humic substances that are insoluble in strongly acidic
solution. They will precipitate from the alkali extract
in acid solutions of pH 2 or less. They can be used as
either soil amendments, foliar applications, or blended
with liquid fertilizers.

Fulvic Acid Fraction – the portion of humic substances that are soluble in bothalkali and acid aqueous solutions.
Hydrophobic Fulvic Acids – are the portions of humic substances that are soluble in both alkali and acidic aqueous solutions that are separated from non-humic aqueous substances in the fulvic acid fraction by selective adsorption onto a nonionic macroporous acrylic ester resin of moderate polarity i.e. DAX-8 resin, at low pH.
Recently the American Association Of Plant Food Chemist Officials (AAPFCO) has approved a testing method to determine the fulvic acid fraction of plant and soil amendments for the purposes of labeling.
“The analytical procedure developed jointly by the Humic Products Trade Association (HPTA) and the International Humic Substances Society (IHSS) has been approved by AAPFCO as the only officially recognized procedure for the analysis of humic acids and a specific category of fulvic acids. The procedure has been published in theJournal of AOAC International, a peer reviewed scientific journal, and is currently being reviewed by the International Organization for Standardization (ISO) as a possible international analytical standard.” Lawrence Mayhew

The market is saturated with products claiming to have high concentration of either humic or fulvic acid. But I have not seen many products with label claims that have used this new method for the quantification of the humic or fulvic content. The individual state regulatory agency’s are slowly adopting the new method as the required method for labeling claims. I recommend you contact the manufacturer of your humic and fulvic acid products and urge them to lead the way.

Ferti-Organic Soluble Fulvic Acid analysis IHSS-HPTA Lamar method