Exactly what are humates? Basically, humates, which are naturally present in organic soil matter, are the salts of humic acids. There are three types of humates: humic acids, fulvic acids and humin. Only humic and fulvic acids currently play a role in hydroponics.

Humic acids are the primary extractable component of humic substances. As complex aromatic macro molecules comprised of amino acids, sugars, peptides, and aliphate compounds, they have a greater molecular weight than fulvic acid. Humic acids aren't water soluble under acidic conditions; they require a pH level higher than 2. Also, humic acids can be extracted from soil with various reagents and are dark brown to black in color.

Fulvic acids by contrast, represent only a fraction of all humic substances. However, fulvic acids are generally more plant active than humic acids due to their higher oxygen content and abundance of carboxyl groups. Another difference between the two is that fulvic acids are soluble in any pH level. They remain in a solution even after the removal of humic acids and are light yellow to yellow brown.

The primary benefit of both humic and fulvic acids is improved plant growth. Humic acids enhance the nutrient richness of soil resulting in stronger, healthier, better producing plants. Equally important, to eco-conscious hydroponic growers, there are no known detrimental side effects from using humic acids.

Several studies, from late 1950's to those performed within the last few years, establish the importance of these acids to plant development. Specifically, humic acids increase the rate and percentage of seed germination, stimulate plant growth by accelerating cell division, improve the uptake of phosphates from fertilizers, act as a buffer to any salinity or toxicity in liquid fertilizers, increase the rate of root development and ultimately, increase overall yield. Humic acids accomplish this by partly by assisting the conversion of mineral elements into a plant-absorbable form. Elements such as manganese and iron in particular, which are usually added to hydroponic systems as a synthetic chelated compound, are made readily available to plants in the form of humic and fulvic acid.

Research conducted by Dr. Vladimir Vaslenko of Canada's CERES Corporation on 'Rhapsody' tomatoes showed an overall "changed growth pattern among treated tomatoes" including increased stem and height diameter, as well as increased leaf chlorophyll. The latter finding is of critical importance, since there's a close correlation between increased chlorophyll, improved photosynthesis, and the final biomass and yield of crops. According to the study, humic and fulvic acids increased the amount of chlorophyll in the tomato leaves by approximately 10%. The study emphasizes that photosynthesis in a plant's upper leaves is key to the plant's eventual yield; the use of humates results in 16 to 17% larger tomatoes as well as a slight increase in the overall number of tomatoes produced. The influence of humic acid on tomato plants is also backed by a 1999 study produced by the International Symposium on Growing Media and Hydroponics. The study specified positive results for humate treated plants even cases of suboptimal pH values and suboptimal electric conductivity, two common stress factors for hydroponic-raised plants.

In a study produced by Dr. Lynette Morgan, the Director of Research at New Zealand's SUNTEC International Hydroponic Consultants, the effect of fulvic acid on green been plants also produced positive conclusions: treated plants experienced a 36% increase in bean weight at harvest, a 36.5% increase plant growth, and they flowered on average four days ahead of the control plants. Simply put, these studies indicate the use of humates results in bigger plants and bigger veggies and quicker harvests.

Yet according to Luscar Ltd., one of the leading researchers and developers of humate products, one of the current challenges to widespread humate use in hydroponic systems is quality: "Quality products that are readily available on a commercial scale must be consistent to achieve success… Key parameters need to be identified and methods for analyzing such deposits have to be more quantifiable." The future of humates products, says one Luscar study on "Leonardite and Humified Organic Matter," rests on the creation of high quality, results oriented, environmentally-friendly humate products.

Fortunately, there are several products currently on the market striving to meet this challenge. Whether you're gardening professionally or as a hobby, humate containing products are one option to consider for improved plant growth.

References:
"Hydroponics and Humates: Acids for Modern Agriculture" (Dr. Vladimir Vaslenko, The Growing Edge September/October 2002)

Hydroponic Humates" (Dr. Lynette Morgan, Maximum Yield July/ August 2001)

"Effects of Lactate, Humate, and Bacillus Subtilis on the Growth of Tomato Plants in Hydroponic Systems" (M. Bohme, International Symposium on Growing Media and Hydroponics 1999)

"Leonardite and Humified Organic Matter" ( D.M Ozdoba et. al., Luscar Specialty Products Division)