The Value of Humate

While all of you should be well aware of the value of the biological components of our products (i.e., mycorrhizal fungi and rhizosphere bacteria), many of you may not fully comprehend the value of some of the other ingredients, like humic acids.

Humate and Humic Acids

Humate is a mineral that is mined from the earth. It is an early stage in the development of coal from organic matter. Humate is rich in humic and fulvic acids, which are active components of soil humus (hence the name “humate”). These water-soluble organic acids not only increase the organic content of the soil, but they also increase the cation exchange capacity (CEC) of soil. The CEC is a measure of the ability of soil to hold and release positively charged mineral ions (cations) in the root zone.

Humic acids have many negatively charged sites along the length of the molecule. These sites attract and hold positively charged mineral ions like iron, magnesium, manganese, calcium, zinc and other micronutrients. The humic acids hold onto these ions and keep them dissolved in solution, preventing them from becoming electrostatically attached to particles of soil. This is important for plants, because plants can only absorb minerals that are dissolved in water.

Soil particles have negative charges too, and will also grab and hold these minerals. To get these minerals, plant roots have to actively detach them from soil particles using an electrochemical trick called “cation exchange.” In cation exchange, the root cells release the desired mineral cations from soil by trading (or “exchanging”) hydrogen ions (H+) for them. Humic acids can save plants a lot of work, by grabbing onto minerals and keeping them dissolved before they can become electrostatically attached to soil particles. Once they are complexed with humic acids, minerals tend to remain soluble longer, without re-attaching to soil particles. So humic acids improve the nutritional value of the soil by reducing the tendency of valuable minerals to electrostatically attach to soil particles. At the same time, humic acids readily support the absorption of these minerals by roots. This is what is meant by “increasing the cation exchange capacity of soil.” Improving the CEC improves the mineral nutritional value of the soil for plants. Stated in brief terms, humic acids aid in the uptake of mineral nutrients by plants.

As a natural organic material, humate is very slowly biodegraded by soil microbes like saprophytic bacteria and fungi. Since it attracts and holds various mineral ions, humate can serve as a mineral source.

Many of LebanonTurf’s biological products contain humate in one form or another. Insoluble products contain granular humate, which is about 65% humic acid. Our soluble products contain a soluble version of humate called “ROOTS Humex WS.” Humex is a proprietary soluble extract of humate, which is unique in being soluble over the entire pH range found in most landscape soils, both acid and alkaline. This allows HumexTM to hold mineral cations in solution over a very broad range of soil pH. Other brands of soluble humate cannot do this as well.

Humic acids:

  • Increase the organic content of the soil
  • Increase the nutritional value of the soil by increasing the cation exchange capacity (CEC) of the soil
  • Aid in the uptake of mineral nutrients by plants