Talk:Humic substance

Humic acid is not a humic substance

This article has many serious problems, starting from its name. Apparently "humic substance" is a relatively rarely used term and concept, which refers to compounds present in untreated humus; whereas "humic acid", "fulvic acid" and "humin" are not "humic substances", but compounds derived from humus by chemical treatment. While "humic acid" and "fulvic acid" have indefinite chemical composition, they are defined operationally well enough to deserve their own articles (just as "coal tar" deserves an article separate from "tar", and "turpentine" from "rosin"). There seems to be a lot of research on humic and fulvic acids and their uses.
Whether "humic substance" should be a separate article or just a section of the humus article, it should focus on the unmodified substances. The article should be moved back to "humic acid", and that name should come first in bold in the lead section; and contents that refers to (unmodified) "humic substances" should go to humus
Moreover, the article makes it seem that the most important thing about the concept is the controversy or controversies, which in fact are relatively peripheral. The focus of the article must be the extraction, composition, properties, and agricultural/ecological relevance (or lack thereof), with the controversies discussed in a section further down the article.. --Jorge Stolfi (talk) 02:13, 12 October 2018 (UTC)

I completely agree. Feel free to take a crack a a major revision, perhaps using the fulvic acid entry an a template.Mukogodo (talk) 18:35, 26 November 2018 (UTC)

Comments

This page needs to be linked to Water Quality and treatment for the purpose of making drinking (potable) water.

The presence of humic acid in water intended for potable or industrial use can have a significant impact on the treatability of that water and the success of chemical disinfection processes. Accurate methods of estabishing humic acid concentrations is therefore essential in maintaining water supplies

This area needs to exapanded upon as it is is deals with public health related issues. any assistance would be appreciated

Scientific critic on the concept of humic substances

Recently, there is a substancial amount of critique in the scientific community regarding the chemistry of humic substances, and whether these operationally defined substances are really a good good model to study natural organic matter. The critique focuses on whether extraction methods for humic substances alter their chemistry, and whether humic substances can be found in untreated soils. I think this aspect should be discussed in the article.

Here are some key articles on the topic: http://www.nature.com/nature/journal/v478/n7367/full/nature10386.html http://www.sciencedirect.com/science/article/pii/S0065211310060037 Nagchampa (talk) 15:48, 22 November 2012 (UTC)

Article focus

Articles should focus on the topic in the title. This article spends most of it's time focusing on the properties of humic substances. Perhaps that material should be moved to humic substances which redirects here. Currently this article never tells us much about humic acid, structure, chemical properties, etc. I know nothing about it, so I wouldn't really be much help. Thanks - Taxman ^Talk 14:20, 31 August 2007 (UTC)

I agree. I couldn't find in the article what led me to it out of curiosity in the first place: what kind of compounds makes humic acids (or substances)? Some are mentioned (amino acid residues, quinones, etc.), but they don't seem to be the major components. I ended up still not knowing an example of a humic acid and its actual chemical composition. --UrsoBR (talk) 01:17, 23 January 2009 (UTC)

Big molecule... I looked up Humic Acid and Fulvic Acid in Beilstein Crossfire. Fulvic Acid is 3,7,8-Trihydroxy-3-methyl-10-oxo-4,10-dihydro-1H,3H-pyrano[4,3-b]chromene-9-carboxylic acid - C14H12O8, whereas Humic Acid is (2-[3-Carboxy-3-(3-carboxy-2,4-dihydroxy-6-methyl-5-carboxy-phenyl)-2-hydroxy-1-methyl-propyl]-5-(3,4-dicarboxy-2-oxo-butyl)-4,6-dihydroxy-isophthalic acid - C28H26O20. The other acids mentioned on this page gave no hits. I'll try to put the Humic Acid structure on the main page.

Health Issues

I have been redirected here after searching for fulvic acid, which I was interested in because of its links to health issues. However, this article does not speak about these issues at all. Perhaps there is an argument for expanding the page on fulvic acid in regards to this? Sadly, I am a newcomer to this issue, and as such would not be the one for creating the page —Preceding unsigned comment added by 195.171.88.236 (talk) 21:51, 1 October 2007 (UTC)

It's about 7 years after the request, but I did add such a section. I found several articles on toxicity caused by the presence of fulvic acids in chlorinated drinking water, and no scientific articles at all looking on the effects of fulvic acid on human health.71.174.82.162 (talk) 07:16, 26 December 2014 (UTC)

"Fulvic" has become a buzzword in health food circles, e.g. for "blk water". A google search for "fulvic" points to this page. This article makes claims about the health benefits of fulvic acids which I'm unconvinced its references support. — Preceding unsigned comment added by 2605:A601:989:E00:226:8FF:FEE5:5B63 (talk) 05:39, 22 March 2016 (UTC)

crenic acid

This is another acid found (along with apocrenic acid) in humus. Does anyone know its composition / structure? Jeff Knaggs (talk) 17:20, 7 March 2008 (UTC)

Inline citations

I have added the "Morefootnotes" tag because the second half or 2/3 of the article is unreferenced and one really has no way of knowing how to verify or evaluate the information provided. --UrsoBR (talk) 01:17, 23 January 2009 (UTC)

The reference to footnote 2 at the end of the introductory paragraph is invalid; the articles cited make no claims regarding the permeability of membranes to colloids. Small chelates have been shown to cross membranes under special circumstances, but colloids are simply too large to do so. — Preceding unsigned comment added by Rskurat (talk • contribs) 04:17, 14 July 2015 (UTC)

That's what I came to point out. It looks as though this was an accident, though. The citation was added to support the claim that fulvic acid had been synthesised, where there had previously been a claim that it had not been. The statement about synthesis was moved into a quote attached to the citation, but in a way that doesn't display (formatting error?) so it looks as though the [2] belongs to the previous sentence.

Ok. I'm not going to get in an edit war about this, but citation 2 does not, under any possible interpretation of its text, support the sentence it's attached to. It's misleading. — Preceding unsigned comment added by 47.72.211.22 (talk) 06:32, 3 August 2015 (UTC)

Ancient masonry

It seems far more likely that the function of straw in bricks is that of fibrous reinforcement rather than modification of the clay through the reaction withhumic action. Unless this claim can be backed by a reliable citation, it should be removed. StainlessSteelDoctor (talk) 21:23, 25 May 2010 (UTC)

Why 'ancient masonry' at all? This material is called adobe, it was widely used wherever the climate is suitable for it (Mediterranean and warmer, also Ukraine). 92.249.121.125 (talk) 11:51, 20 February 2011 (UTC)

Fulvic Acid

Why does Fulvic Acid redirect to this page? Are they synonomous? This article discusses them as if they are two different, yet related, materials. It would help if this were explained in greater detail. —Preceding unsigned comment added by 12.188.233.14 (talk) 15:11, 14 April 2011 (UTC)

I read it as Fulvic acids being a subset of Humic acids. — Preceding unsigned comment added by 71.63.69.193 (talk) 06:14, 15 December 2011 (UTC)

The Fulvic Acid aspect I have only come across in connection with diet and health fads, and what I've seen elsenet is classic exploitative snake-oil selling in style. Yes, new science keeps appearing, but I haven't seen any science yet. Dragging in fulvic acids rings a faint alarm bell for me. Yes, call this comment "original research", but be careful.

Humic and fulvic acid are fractions of natural organic matter (NOM). They are defined operationally. The humic acids precipitate from solution at pH < 2. Likewise, the fulvic acids remain in solution. Both are complex mixtures of many organic compounds. Most aquatic NOM is fulvic acid, while a greater fraction of soil NOM (SOM) is humic acid. Humic acids generally have higher molecular weights. NOM binds metals, and so that could be the source of health claims (although I will not take that issue on). — Preceding unsigned comment added by 98.227.21.181 (talk) 04:44, 22 October 2013 (UTC)

Above comment has it correct. As far as whether or not Fluvic and Humic acids are synonymous, remember that nature doesn't give a fig about our definitions or labels. These particular materials are less discrete (like letters of the alphabet) and on more of a continuum, like colors. You know when something is yellow, and when it is green, but where exactly do you change over from yellow-green to green-yellow? Similarly, there is no fundamental property which distinguishes fulvic and humic acids unambiguously. Scientists have generally settled on the definition given above. It is also known that fulvic acid have a higher oxygen content than humic acids, and lower molecular weights. As for the article, I will consider compiling my thoughts on an edit and presenting it to the talk page for discussion. Equilshift (talk) 21:42, 29 July 2014 (UTC)

fulvic acid

24.50.151.151 (talk) 14:32, 7 October 2014 (UTC) http://aggie-horticulture.tamu.edu/newsletters/hortupdate/hortupdate_archives/2002/jun02/art4jun.html Humic acid can be extracted from any material containing well-decomposed organic matter - soil, coal, composts, etc. Extraction is by way of treatment of these materials with a solution of sodium hydroxide. This dissolves much of the organic matter present. If we then take this solution and add enough acid to drop its pH to about 2, organic material will begin to flocculate and can be separated from the liquid portion. The flocculated material is humic acid. What remains in solution is fulvic acid.

If we take the flocculated humic acid and dry it down to form a black mass that can be crushed and sized by dry sieving, we have humate. In other words, humate is humic acid in its solid state. Therefore, the chemical properties of humate and humic acid are basically the same. I wish there was more but this is the only reference to fulvic acid I found.

Charcoal

I added charcoal in soil as an example of a biotic material subject to humification, resulting in humic acid. Conceptual models relating to humic acid formation do not support a large charcoal-derived component. Black carbon is normally between 5 and 50% of soil organic carbon. Ponomarenko (2001) posited that conceptually processing the reality of large char-C stocks in soil will require considerable change in conceptual understanding of soil humus.

Ponomarenko, E.V.; Anderson, D.W. (2001), "Importance of charred organic matter in Black Chernozem soils of Saskatchewan", Canadian Journal of Soil Science, 81 (3): 285–297, The present paradigm views humus as a system of heteropolycondensates, largely produced by the soil microflora, in varying associations with clay. Because this conceptual model, and simulation models rooted within the concept, do not accommodate a large char component, a considerable change in conceptual understanding (a paradigm shift) appears imminent.

The paradigm shift is still on back-order, so basically, that one(1) edit to add charcoal, that's all I have at this point. -- Paleorthid (talk) 22:47, 10 February 2016 (UTC)

Criticism of humic acid theory

I propose a new section, Criticism...: With an explanation build around these excerpts from Lehmann, J.; Kleber, M. (2015-12-03), "The contentious nature of soil organic matter", Nature, 528, doi:10.1038/nature16069:

[biogeochemical] processes convert dead plant material into organic products that are able to form intimate associations with soil minerals, making it difficult to study the nature of soil organic matter. Early research based on an extraction method assumed that a 'humification' process creates recalcitrant (resistant to decomposition) and large 'humic substances' [such as humic acid] to make up the majority of soil 'humus'. However, these 'humic substances' have not been observed by modern analytical techniques. This lack of evidence means that 'humification' is increasingly questioned, yet the underlying theory persists in the contemporary literature, including current textbooks.

The conceptual problem with defining 'humic substances' [such as humic acid] by an extraction process is threefold: 1) ... extraction is always incomplete... 2) ...the harsh alkaline treatment ... giving the resulting 'humic' and 'fulvic' fractions ... an exaggerated chemical reactivity... 3) The development of this extraction preceded theory, tempting scientists to develop explanations ... rather than develop an understanding of the nature of all organic matter in soil. Over time, this attempt to mechanistically explain the formation of operationally defined 'humic substances' also led to their definition as synthesis products without the link to the alkaline extraction. -- Paleorthid (talk) 17:48, 26 February 2016 (UTC)

Update: The criticism section has been tagged for the last year, as compromising the NPOV of the article. I am going through the article, distinguishing humic substances in nature vs humic acids in the lab, as a soil amendment, as a product. -- Paleorthid (talk) 19:59, 23 January 2019 (UTC)

This section relies on a single source. If additional independent supporting sources cannot be found for it, it should go altogether. --Kent G. Budge (talk) 02:46, 26 October 2020 (UTC)

I know nothing about humus and have no axe to grind here. However, I am a working scientist and do know that J. Random Crackpot does not get to publish a peer-reviewed Perspective in Nature. Not that I am under any illusion that if it's peer-reviewed it must be right, but it does deserve to be taken seriously. It certainly shouldn't be lumped in with the typical pseudoscience that Wikipedia's rules of thumb are designed to weed out. I would be very circumspect about any deletion of content. A good route forward might be to do a reverse lookup (Science Citation Index/Web of Science) for more recent papers citing the 2015 Nature piece and see what sort of reception it has gotten or further work it may have sparked. Gould363 (talk) 15:16, 26 October 2020 (UTC)

Technological applications to water treament

Concerning the technological applications, I think we can remove this very specific application which seems still at the research state and focus on more largely used methods of removal of metals by complexation floculation for instance. I would the rename the paragraph and maybe merge it with 'health issues' to create a 'humic substances in water treatment'. Also, the relevance of the Ancient masonry paragraph seems a bit thin . The fact that straw releases humic acid seems a bit too general to deserve a paragraph of its own in my opinion. Hidodu (talk) 09:29, 28 March 2018 (UTC)

Please see related discussion at Talk:Humus -- Paleorthid (talk) 00:08, 27 February 2016 (UTC)