Humic Acid


The peer-reviewed international journal Agronomy 2016, 6(4), 50 ( published a Review on 28 October 2016 by Drs Graham Lyons and Yusuf Genc entitled “Commercial Humates in Agriculture: Real Substance or Smoke and Mirrors?”, and this is the abstract:

Soil humic substances (HS) are known to be beneficial for soils and plants, and most published studies of HS and humates, usually conducted under controlled conditions, show benefits. However, the value of commercial humate application in the field is less certain. This review attempts to answer the question: How effective are commercial humates in the field? Commercial humates, especially K humate, are used widely in agriculture today as “soil conditioners”. A wide range of benefits is claimed, including growth of beneficial soil microbes; deactivation of toxic metals; improvements in soil structure including water retention capacity, enhanced nutrient and micronutrient uptake and photosynthesis; resistance to abiotic stress, including salinity; and increased growth, yield and product quality. Despite this, there is a surprising lack of solid evidence for their on-farm effectiveness and findings are often inconsistent. The industry relies largely on anecdotal case studies to promote humates, which are often applied at unrealistically low levels. It is recommended that products should be well characterised, physically and chemically, and that careful field studies be conducted on foliar humate application and pelletised humates at realistic rates, targeted to the seedling rhizosphere, for a variety of crops in a range of soils, including low C sandy and saline soils.

These are some quotes from the Review:

“A lack of solid evidence has not inhibited enthusiastic promotion of humate products by some businesses, and “unfortunately, many of the small (fertiliser) companies make unsubstantiated and often ridiculous claims about humic (and fulvic) acids, which gives these products a poor image when the supposed results do not eventuate.””

The authors refer to an article written by Dr D.C. Edmeades from New Zealand ( This is a must read article and I give two quotes here:

“Having unjustly put the fear-of-god into the farmer’s mind, the next step in their advertising is to present their “solution.””

“Graeme Sait of Nutri-Tech Solutions says: “Humates are now recognized as the single most productive input in sustainable agriculture.””

The authors of the Agronomy Review conclude “that the smoke and mirrors description of commercial humates is currently more appropriate than real substance.”, i.e. commercial humates are basically a waste of money for on-farm use.

Why is the situation like this? The authors explain: “Vendors know they will not be prosecuted, regardless of their claims (bold type mine), and researchers have called for mandatory quality control by regulatory bodies.” In other words, government regulators such as Departments of Agriculture are failing to take action against the exaggerated and ludicrous claims being made for commercial humates by companies selling these products. Therefore, BUYER BEWARE!

Does this mean that soils cannot be improved by the addition or replenishment of humates? Not at all! The journal Agronomy 2016, 6, 45 ( on 28 September 2016 published my communication entitled “Replenishing Humic Acids in Agricultural Soils”, and this is the abstract:

For many decades, it was commonly believed that humic acids were formed in soils by the microbial conversion of plant lignins. However, an experiment to test whether these humic acids were formed prior to plant matter reaching the soil was never reported until the late 1980s (and then only as a side issue), even though humic acids were first isolated and reported in 1786. This was a serious omission, and led to a poor understanding of how the humic acid content of soils could be maintained or increased for optimum fertility. In this study, commercial sugar cane mulch and kelp extracts were extracted with alkali and analyzed for humic acid content. Humic acids in the extracts were positively identified by fluorescence spectrophotometry, and this demonstrated that humic acids are formed in senescent plant and algal matter before they reach the soil, where they are then strongly bound to the soil and are also resistant to microbial metabolism. Humic acids are removed from soils by wind and water erosion, and by water leaching, which means that they must be regularly replenished. This study shows that soils can be replenished or fortified with humic acids simply by recycling plant and algal matter, or by adding outside sources of decomposed plant or algal matter such as composts, mulch, peat, and lignite coals.

My long-time research in the field of humic acids has shown that it is vital to replenish soil humic acids content, and the best ways to do this is by recycling plant matter or to add outside sources of decomposed plant or algal matter such as composts, mulch, peat, seaweed and lignite coals. An added benefit to this approach is the low cost compared to commercial humates.







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