What are Humic Substances?

Humic substances (HS) are natural substances belonging to the soil organic matter and resulting from the decomposition of dead cell materials and from the metabolic activity of soil microbes using these substrates. HS are collections of heterogeneous compounds, originally classified according to their molecular weights and solubility into insoluble humins, humic acids and fulvic acids, but with loosely defined boundaries and complex molecular constituents. This area is expanding all the time with new organic acids being isolated and used for different purposes from cation exchange capacity increase, foliar nutrient delivery and even complexed nutrient chelation and ISR/ASR stimulated crop response.

HS are ubiquitous, they can be found throughout soils and groundwater including rivers streams and lakes. The richest sources on HS are typified by Leonardite, an ore found in open-cast coal mining, yet lignite (peat-coal) and lake beds can also be rich sources of HS for extraction. Humic acids used in biostimulants are usually Humates which are produced by the alkaline extraction of humic acids from HS rich sources. Good HS sources will also yield lower molecular weight and more soluble Fulvic acids at around 4-1 Humates vs Fulvic acid. The combination of the two is normally found in the most effective biostimulants.

Benefits:

Humic acids are found at the highest levels in the most fertile soils. Poor fertility soils can be improved by the addition of longer carbon-chain HS, improving CEC and enhancing nutrient availability. Secondly, humic acid changes the activities of sucrase, urease, and phosphatase in the soil, and enhances the metabolism of many substances in the soil. The change in enzyme activity also positively affects soil beneficial microbial activity. Increased root development and consequent yield increases are common.

In foliar formulations HS can beneficially influence the uptake and translocation of metal cations and other substances in proprietary formulations. Fulvic acids are known to improve membrane permeability in a complementary effect.

Environmental Impact:

HS are used to improve environmental remediation of heavy metals. there are no negative environmental impacts, only positive ones.

Other Uses:

HS and particularly Fulvic acid are naturally occurring ingrediens in many dietary supplements with many beneficial applications in human health. Veterinarians first discovered the substance’s impact after observing that livestock that grazed near these deposits experienced better long-term health. Those positive effects have translated to humans as well, evolving into the following applications:

Liquid mineral dietary supplement; Efficacy/stability-enhancing ingredient; Nutrient bio-availability boosting material. It’s a source of essential minerals, amino acids, electrolytes, and antioxidants; Improves nutrient uptake and assimilation; It’s a natural chelator for detoxification effects; Enhances cellular function through participation in oxidation-reduction (redox) reactions; Promotes gut health and immune function.

Research References:

1. 1. Chen, X. G. et al. Responses of root physiological characteristics and yield of sweet potato to humic acid urea fertilizer. Plos one. 12(12), e0189715 (2017).
   2. Suman, S., Spehia, R. S. & Sharma, V. Humic acid improved efficiency of fertigation and productivity of tomato. Journal of plant nutrition. 13 Jan, 439–446 (2017).
   3. Selladurai, R. & Purakayastha, T. J. Effect of humic acid multinutrient fertilizers on yield and nutrient use efficiency of potato. Journal of Plant Nutrition. 39, 949–956 (2016).
   4. Khan, R. U. et al. Effect of humic acid on growth and crop nutrient status of wheat on two different soils. Journal of plant nutrition 28 Nov, 453–460 (2017).
   5. Ahmad, T., Khan, R. & Khattak, T. N. Effect of humic acid and fulvic acid based liquid and foliar fertilizers on the yield of wheat crop. Journal of plant nutrition. 29 Oct (2018).
   6. Jindo, K. et al. Root growth promotion by humic acids from composted and non-composted urban organic wastes. Plant Soil. 353, 209–220 (2012).
   7. Li, Z. J. & Ma, G. R. The recent situation for manufacturing urea humic acid and mechanism in increasing crop yield. Chinese Journal of soil Science. 35, 799–801 (2004).
   8. Yan, X., Jin, J. Y., He, P. & Liang, M. Z. Recent advances in technology of increasing fertilizer use efficiency. Scientia Agricultura Sinica. 41, 450–459 (2008).
   9. Selladurai, R. & Purakayastha, T. J. Effect of humic acid multinutrient fertilizers on yield and nutrient use efficiency of potato. Journal of plant nutrition. 09 Nov, 949–956 (2015).
   10. Gao, H. J., Luo, G. & Lin, B. The progress of humic acid on conservation and remediation of tobacco-growing soil and tobacco leaf quality. Humic Acid (in China). 2, 16–20 (2017).
   11. Wang, L. B. & Wang, Y. X. Effects of humic acid fertilizer on soil nutrients and microbial activity. Humic Acid (in China). 4, 6–9 (2011).