Humic Acid vs Fulvic Acid for Plants + Gardens: Ask the Doc

HTG's Dr. Myers goes over the origins of Humic and Fulvic Acids and discusses the benefits and methods of using them in your garden.

Current scientific studies show that the fertility of soil is determined to a very large extent by the content of humic acids. Their high cation-exchange capacity (CEC), the oxygen content as well as the above average water holding capacity are the reasons for the high value of using humic acids for improving soil fertility and plant growth. The most important feature of humic acids lies in their ability to bind insoluble metal ions, oxides and hydroxides, and to release them slowly and continually to plants when required.

Fulvic acid is the lowest molecular weight portion of humic substances. By definition it will be golden in color where humic acid will be brown to black. Because of its small molecular size, fulvic acid is able to penetrate the leaf and even the mitochondria of a cell which makes it great for foliar sprays and root drenches. By comparison humic acid is a fantastic soil conditioner and better for dry broad cast and soil/soil-less application. Typically each manufacturer will provide a product analysis differentiating the fulvic from the humic; however some states do not accept fulvic acid analysis and will refer to all substances as humic acids. To further confuse things, a standardized industry method for analyzing humic substances does not exist. This creates a wide range of concentrations and analysis for humic products. At the end of the day it is best to conduct bioassays and test the products yourself to see which one will perform best.