Humic Acid(s) - What's the Deal?
By Chris Williams
Chris Williams is a product manager for Helena Chemical Company and a former golf course superintendent. He covers the turf, ornamental, lawn care, and industrial vegetation management markets in the eastern United States, from VT to FL. Chris lives in North Myrtle Beach, SC.
Just what is the deal anyway? Carbon, humic acid(s), organic acids, and many other terms seem to be everywhere in the Turf and Ornamental world. These products have been widely discussed and marketed in the Green Industry. But importantly, what should you be looking for in these products? In this article I would like to shine some light on this topic, mainly concerning what they are and what constitutes a quality product. Hopefully, this will bring some clarity to this very confusing area of many nutritional programs.
Carbon, Humic Acid(s), & Organic Acids
Carbon is a very popular word in the world of turf grass maintenance today. Carbon is an essential nutrient and needed to fulfill nutrient usage and other processes inside the plant, but is there a difference in “carbon” sources? The answer is ABSOLUTELY! We should talk about carbon in general, but is it the carbon doing the work, or something deeper? It is actually, something deeper, and the answer is humic acid(s) and other organic acids. Humic acid(s) are the workhorse within the carbon chain pulling off all these wonderful miracles in nature. Carbon with no humic acid(s) is just carbon; it looks good, feels good, but contains no real value to the plant or the user.
There are wide variations in humic acid(s) because of geography, history, and the collection. Geography identifies the origin of the parent material, including those from fresh or salt water sources. For example, materials mined from grassland humic acid(s) deposits typically have equal amounts of fulvic acid (FA), grey humic acid (GHA), and brown humic acid (BHA); whereas forest-derived humic acid(s) lead to FA making up half to a little more than half, and then split almost evenly between the GHA and BHA in composition. Geography is typically one of the “selling points” with these types of products, but this does not mean much in terms of “quality.” Being naturally derived, the percent of active ingredient and usable quality can vary greatly within a mining location. Other variables, such as is the mine location covered in trees/grass or fresh/salt water. Lastly, what is the mining process and where is the mine? Processes used during manufacturing can demolish the functional groups with heat or chemicals, rendering the material useless. In cold, wet climates the materials have to be dried in order to be processed into a usable form. Also, are there other processes or chemicals used in manufacturing to make extraction of the product more user friendly?
Another very important consideration about the quality of the humic acids is the integrity of the source of material. Are the mines owned by the supplier? If they are, the quality of the humic acids should be fairly consistent. But if the supplier is sourcing material from a variety of sources, quality can vary greatly.
You may be wondering why there is an “(s)” following the humic acid(s) throughout the article? That is, because humic acid(s) are not a specific compound. They are made up of carbon with a benzene ring backbone surrounded by functional groups (carboxyl, hydroxyl, ketones, and amines). Molecules will vary depending on the parent material and the reasons stated above. Does decayed animal matter look like a decayed tree on a molecular level? A humic acid(s) product should contain more than just humic acid. As mentioned above FA, GHA, and BHA should also be in the composition.
Fulvic acid is the most plant-active portion of humic acid(s) providing nutrient uptake. The molecular weights of humic acid(s) are expressed as daltons. FA will measure between 700-7,000 daltons. The Grey and Brown factions are measured from 7,000 -700,000 daltons. These materials provide soil building properties ranging from microorganism food sources to nutrient grabbing sites building CEC in the soil. Anything in the product measuring over 700,000 daltons (humin) is considered unusable by the plant and lacking efficacy. All humic acid(s) products contain particles in this range, but how much is outside of the usable range is definitely something to consider when purchasing a humic acid(s) product. You want a product with as much material in the 700-700,000 dalton ranges as possible. As you can see, the “(s)” is important.
Research and Standards
Humic acid(s) in our industry lack a true “standard.” Testing methods used are not widely accepted and, also can be manipulated. Currently, there are six testing methods – each of them different. The two main methods used in the United States are the California Department of Food and Agriculture (CDFA) Gravametric testing procedure and the A&L Colormetric procedure. The differences in these testing procedures is a conversation for another day. Both methods provide good, but not absolute information. The issue is humic acid(s) do not have one molecular fingerprint, such as 2,4-D for example. Each molecule of humic is different in chain length and functional groups, whereas the 2,4-D molecule always looks identical. Academia has a hard time measuring the quantity of humic acid(s) due to these properties. Since each molecule is unique, there is no procedure to test one versus the other without field trials and data. This affects the percent active ingredient also, meaning almost anything can be claimed on the label! You read that correctly, the percent active ingredient can very well be arbitrary. The testing methods used cannot measure absolute percent active ingredient, but testing could be relative if the same testing method was used in our industry. So what does this mean for you?
Rates will vary tremendously! In my travels I hear rates from forty pounds per acre to well over 800 pounds per acre. Often, the rate will vary within a single product. Now you can see why! The maker is not sure where the rate should be, so they make a range for everyone. This is another indication the product may not be as represented!
What should you be looking for in a humic acid(s) product? First, where did it come from? Dig a bit deeper. Just because a product is dark in color does not mean it is effective. Second, what are the ranges (daltons) for each of the main categories - FA, GHA, and BHA? What good is a product that has above 700,000 daltons (humin)? As we discussed, there is little to no benefit in those materials. Is it a humic acid or humic acid(s)? Most importantly, what trials are available with the product you are purchasing? Not just humic acid(s) in general, but trials on the actual product. Now realize this topic goes much deeper and could warrant a day’s discussion, but there is no time or space for that in this article. However, these are fair questions to ask when using your resources to care for your plant material. If your experiences do not show much validity in using humic acid(s) or carbon, I encourage you to try a different product. These materials truly are beneficial. The quality of the material used could be responsible for the poor results!