466:
the theory that a 'humification' process created distinct 'humic substances' like 'humic acid', 'fulvic acid', and 'humin'. However, modern chemical analysis methods applied to unprocessed mineral soil have not directly observed large humic molecules. This suggests that the extraction and fractionation techniques used to isolate humic substances alter the original chemical composition of the organic matter. Since the definition of humic substances like humic and fulvic acids relies on their separation through these methods, it raises the question of whether the distinction between these compounds accurately reflects the natural state of organic matter in soil. Despite these concerns, the 'humification' theory persists in the field and in even textbooks, and attempts to redefine 'humic substances' in soil have resulted in a proliferation of conflicting definitions. This lack of consensus makes it difficult to communicate scientific understanding of soil processes and properties accurately."
1172:
that 'humification' is increasingly questioned, yet the underlying theory persists in the contemporary literature, including current textbooks. The issue has also been approached by redefining 'humic substances' as the portion of soil organic matter that cannot be molecularly characterized or by calling all soil organic matter 'humus'. We argue that this compromise – maintaining terminology but altering its meanings in varying ways – hampers scientific progress beyond the soil sciences. The of soil organic matter does not allow a confusing middle path; it requires leaving the traditional view behind to bring about lasting innovation and progress. This is critical as scientific fields outside the soil sciences base their research on the false premise of the existence of 'humic substances'. Thus an issue of terminology becomes a problem of false inference, with far-reaching implications beyond our ability to communicate scientifically accurate soil processes and properties.
300:(IHSS) advocates the use of standard laboratory methods for preparation of humic and fulvic acids. Humic substances are extracted from soil and other solid sources using NaOH, the humic acids are then precipitated at pH 1, and the soluble fraction is treated on a resin column to separate fulvic acid components from other acid soluble compounds. Humic acid plus fulvic acid are extracted from natural waters using a resin column after microfiltration and acidification to pH 2. The humic materials are eluted from the column with NaOH and humic acid is precipitated at pH 1. After adjusting the pH to 2 the fulvic acid is separated from other acid soluble compounds using a resin column as with solid phase sources. An analytical method for quantifying humic acid and fulvic acid in commercial ores and products, has been developed based on the IHSS humic acid and fulvic acid preparation methods,
376:
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31:
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20:
240:. Humic substances in the lab are very resistant to further biodegradation. The structure, elemental composition and content of functional groups of a given sample depend on the water or soil source and the specific conditions of extraction. Nevertheless, the average properties of lab produced humic substances from different sources are remarkably similar.
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The development of this extraction method preceded theory, tempting scientists to develop explanations for the synthesis of materials resembling operationally extracted 'humic substances', rather than to develop an understanding of the nature of all organic matter in soil. This lack of evidence means
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through its effect on the water-holding capacity of the soil. Also, since plants have been shown to absorb and translocate the complex organic molecules of systemic insecticides, they can no longer discredit the idea that plants may be able to absorb the soluble forms of humus; this may in fact be an
602:
processes. For instance, humic and fulvic acids can react with the chemicals used in the chlorination process to form disinfection byproducts such as dihaloacetonitriles, which are toxic to humans. Accurate methods of establishing humic acid concentrations are therefore essential in maintaining water
479:
Since the dawn of modern chemistry, humic substances are among the most studied among the natural materials. Despite long study, their molecular structure remains elusive. The traditional view is that humic substances are heteropolycondensates, in varying associations with clay. A more recent view is
1295:
The present paradigm views humus as a system of heteropolycondensates, largely produced by the soil microflora, in varying associations with clay (Anderson 1979). Because this conceptual model, and simulation models rooted within the concept, do not accommodate a large char component, a considerable
622:
Extraction procedures are bound to alter some of the chemical linkages present in the soil humic substances (mainly ester bonds in biopolyesters such as cutins and suberins). The humic extracts are composed of large numbers of different bio-organic molecules that have not yet been totally separated
465:
Decomposition products of dead plant materials form intimate associations with minerals, making it difficult to isolate and characterize soil organic constituents. 18th century soil chemists successfully used alkaline extraction to isolate a portion of the organic constituents in soil. This led to
175:
Water solubility of humic substances is primarily governed by interplay of two factors: the amount of ionizable functional groups (mainly carboxylic acid groups) and the molecular weight. In general, fulvic acid has a higher amount of carboxylic groups and lower average molecular weight than humic
631:
Organic matter soil amendments have been known by farmers to be beneficial to plant growth for longer than recorded history. However, the chemistry and function of the organic matter have been a subject of controversy since humans began postulating about it in the 18th century. Until the time of
183:
Age and origin of the source material determine the chemical structure of humic substances. In general, humic substances derived from soil and peat (which takes hundreds to thousands of years to form) have higher molecular weight, higher amounts of functional groups, more carbohydrate units, and
196:
supramolecular associations and composed of a variety of compounds of biological origin and synthesized by abiotic and biotic reactions in soil. It is the large molecular complexity of the soil humeome that confers to humic matter its bioactivity in soil and its role as plant growth promoter.
195:
or the dissolved organic matter and represent the humic molecules distributed in the soil or water. A new understanding views humic substances not as high-molecular-weight macropolymers but as heterogeneous and relatively small molecular components of the soil organic matter auto-assembled in
610:
As a lot of different bio-organic molecules in very diverse physical associations are mixed together in natural environments, it is cumbersome to measure their exact concentrations in the humic superstructure. For this reason, concentrations of humic acid are traditionally estimated out of
341:
A sequential chemical fractionation called
Humeomics can be used to isolate more homogeneous humic fractions and determine their molecular structures by advanced spectroscopic and chromatographic methods. Substances identified in humic extracts and directly in soil include mono-, di-, and
550:
of carboxyl groups and around 8 for protonation of phenolate groups. There is considerable overall similarity among individual humic acids. For this reason, measured pK values for a given sample are average values relating to the constituent species. The other important characteristic is
636:, it was supposed that humus was used directly by plants, but, after Liebig showed that plant growth depends upon inorganic compounds, many soil scientists held the view that organic matter was useful for fertility only as it was broken down with the release of its constituent
204:, at the cost of clarity. There is also a call to forgo the traditional alkali extract method and directly analyze the soil, but its complexity prevents widespread adoption in agriculture. In practice, this means some sources may apply a traditional acid-base analysis to
538:
substituents, linked together; the illustration shows a typical structure. The functional groups that contribute most to surface charge and reactivity of humic substances are phenolic and carboxylic groups. Humic acids behave as mixtures of dibasic acids, with a
623:
and identified. However, single classes of residual biomolecules have been identified by selective extractions and chemical fractionation, and are represented by alkanoic and hydroxy alkanoic acids, resins, waxes, lignin residues, sugars, and peptides.
1887:
And since plants have shown their ability to absorb and translocate the complex molecules of systemic insecticides, they can no longer discredit the idea that plants are able to absorb the soluble humic nutrients, containing by far
648:
A study on the effects of humic acid on plant growth was conducted at Ohio State
University which said in part "humic acids increased plant growth" and that there were "relatively large responses at low application rates".
1878:
1443:
Synthesis of fulvic acid (1a) was accomplished by a route involving selective ozonization of 9-propenylpyranobenzopyran (1c), obtained by a regioselective cyclization of the 2-methylsulphinylmethyl 1,3-dione(3c)
199:
The academic definition of humic substances is under debate as "humification" becomes unsupported as a special case, leading to some radical definitions expanding HS to encompass all difficult-to-characterize
652:
A 1998 study by scientists at the North
Carolina State University College of Agriculture and Life Sciences showed that addition of humate to soil significantly increased root mass in creeping bentgrass turf.
216:
The formation of humic substances in nature is one of the least understood aspects of humus chemistry and one of the most intriguing. There are three main theories to explain it: the lignin theory of
1560:
found very little in the way of humic macromolecules in mineral soils. Instead, evidence suggests that the alkali extraction process itself actually creates giant polymers from smaller biomolecules.
1879:
Pan
American Union. Dept. of Cultural Affairs. División de Fomento Científico, Pan American Union. Dept. of Scientific Affairs, Organization of American States. Dept. of Scientific Affairs (1984).
113:
This definition of humic substances is largely operational. It is rooted in the history of soil science and, more precisely, in the tradition of alkaline extraction, which dates back to 1786, when
1744:
Tipping, E (1994). "'WHAM – a chemical equilibrium model and computer code for waters, sediments, and soils incorporating a discrete site/electrostatic model of ion-binding by humic substances".
1867:
The value of adding organic matter to the soil in the form of animal manures, green manures, and crop residues for producing favorable soil tilth has been known since ancient times
2201:
1456:
Nebbioso A. and
Piccolo A. (2012). "Advances in humeomics: Enhanced structural identification of humic molecules after size fractionation of a soil humic acid".
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from organic feedstocks directly. These artificial substances may be similarly divided into artificial humic acid (A-HA) and artificial fulvic acid (A-FA).
334:
As a nutrition supplement, fulvic acid can be found in a liquid form as a component of mineral colloids. Fulvic acids are poly-electrolytes and are unique
1527:
798:
since the 1970s, with nearly 60,000 metric tons produced by 2016. Humate deposits may also play an important role in the genesis of uranium ore bodies.
1048:
Nebbioso A. and
Piccolo A. (2011). "Basis of a Humeomics Science: Chemical Fractionation and Molecular Characterization of Humic Biosuprastructures".
660:
infectivity in laboratory experiments, but that this effect may be uncertain in the environment due to minerals in the soil that buffer the effect.
1900:
224:(1911). Those theories are insufficient to account for observations in soil research. Humic substances are formed by the microbial degradation of
94:"Humic substances" is an umbrella term covering humic acid, fulvic acid, humin, and hymatomelanic acid, which differ in solubility. By definition,
2268:"Uranium deposits in the Poison Canyon trend, Ambrosia Lake Subdistrict, Grants Uranium District, McKinley and Cibola Counties, New Mexico"
640:
elements into inorganic forms. At the present time, soil scientists hold a more holistic view and at least recognize that humus influences
2202:"Youngs, R.W. & Frost, C.M. 1963. Humic acids from leonardite – a soil conditioner and organic fertilizer. Ind. Eng. Chem., 55, 95–99"
1951:
Cooper, R. J.; Liu, Chunhua; Fisher, D. S. (1998). "Influence of Humic
Substances on Rooting and Nutrient Content of Creeping Bentgrass".
1914:
Arancon, Norman Q.; Edwards, Clive. A.; Lee, Stephen; Byrne, Robert (2006). "Effects of humic acids from vermicomposts on plant growth".
1666:
Humus accounts for 50 to 90% of cation exchange capacity. Like clays, humus colloids and high surface area char hold nutrient cations
945:
Drosos M.; et al. (May 15, 2017). "A molecular zoom into soil
Humeome by a direct sequential chemical fractionation of soi".
574:
with ions such as Mg, Ca, Fe, and Fe. Many humic acids have two or more of these groups arranged so as to enable the formation of
1446:(Note: this paper represents an attempt to produce fulvic acid, but the real extract is again a mixture of variable composition.)
713:(w/c) of fresh concrete while preserving its workability. The w/c ratio of concrete is one of the main parameter controlling the
386:
1014:
The
Molecular Composition of Humus Carbon: Recalcitrance and Reactivity in Soils. In: The Future of Soil Carbon, Wiley and Sons
297:
1186:"Compost and crude humic substances produced from selected wastes and their effects on Zea mays L. nutrient uptake and growth"
717:
of hardened concrete and its durability. The same wood pulping process can also be applied to obtain humus-like substances by
444:
323:. Commercial humic acid used to amend soil is manufactured using these same well established procedures. Humic acids can form
2334:
1708:
1618:
1537:
2152:
Gong, Guanqun; Xu, Liangwei; Zhang, Yingjie; Liu, Weixin; Wang, Ming; Zhao, Yufeng; Yuan, Xin; Li, Yajun (3 November 2020).
416:
1603:
The
Supramolecular structure of humic substances. A novel understanding of humus chemistry and implications in soil science
1572:
Ponomarenko, E.V.; Anderson, D.W. (2001), "Importance of charred organic matter in Black Chernozem soils of Saskatchewan",
1408:
1277:
Ponomarenko, E.V.; Anderson, D.W. (2001), "Importance of charred organic matter in Black Chernozem soils of Saskatchewan",
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complexes. The formation of (chelate) complexes is an important aspect of the biological role of humic acids in regulating
2208:
1429:
Yamauchi, Masashige; Katayama, Sadamu; Todoroki, Toshiharu; Watanable, Toshio (1984). "Total synthesis of fulvic acid".
2119:
Yakimenko, Olga; Stepanov, Andrey; Patsaeva, Svetlana; Khundzhua, Daria; Osipova, Olesya; Gladkov, Oleg (3 July 2021).
1860:
423:
255:
Humic and fulvic acids are extracted from soil and other solid phase sources into a strongly basic aqueous solution of
806:
The heavy-metal binding abilities of humic acids have been exploited to develop remediation technologies for removing
2300:
Yurishcheva, A.A.; Kydralieva, K.A.; Zaripova, A.A.; Dzhardimalieva, G.I.; Pomogaylo, A.D.; Jorobekova, S.J. (2013).
1643:
1029:
2121:"Formation of Humic-Like Substances during the Technological Process of Lignohumate Synthesis as a Function of Time"
1012:
Piccolo A.; et al. (2018). "The Molecular Composition of Humus Carbon: Recalcitrance and Reactivity in Soils".
758:. This form of "mineral-derived fulvic acid" is widely used in China. This process also occurs in nature, producing
136:
In terms of chemistry, fulvic acid, humic acid, and humin share more similarities than differences and represent a
668:
Humans can affect the production of humic substances via a variety of ways: by making use of natural processes by
861:
430:
248:
Humic substances in soils and sediments can be divided into three main fractions: humic acids, fulvic acids, and
1264:
1243:
401:
1308:
Mao, J.-D.; Johnson, R. L.; Lehmann, J.; Olk, D. C.; Neves, E. G.; Thompson, M. L.; Schmidt-Rohr, K. (2012).
177:
412:
1822:
Peters, Ruud J.B.; De Leer, Ed W.B.; De Galan, Leo (1990). "Dihaloacetonitriles in Dutch drinking waters".
1409:"Effects of Humic Acid on Animals and Humans: An Overview of Literature and a Review of Current Research"
2324:
1779:
Oliver, Barry G. (1983). "Dihaloacetonitriles in drinking water: Algae and fulvic acid as precursors".
1310:"Abundant and stable char residues in soils: implications for soil fertility and carbon sequestration"
1928:
814:
with humic acids. After capturing lead ions, the nanoparticles can then be captured using a magnet.
1999:
1334:
733:
616:
481:
289:
Fulvic acids is left in solution at pH 1. They remain soluble independent of pH and ionic strength.
53:
residues. The colour of humic substances varies from yellow to brown to black. The term comes from
1491:
Drosos M. and Piccolo A. (2018). "The molecular dynamics of soil humus as a function of tillage".
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988:
137:
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A typical humic substance is a mixture of many molecules, some of which are based on a motif of
130:
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343:
221:
80:
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2233:
1964:
1852:
McGraw-Hill encyclopedia of science and technology: an international reference work, Volume 12
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729:
714:
540:
437:
1979:
125:(i.e., humic acid). Aquatic humic substances were isolated for the first time in 1806, from
2067:
2000:
Kuznetsova, Alsu; Cullingham, Catherine; McKenzie, Debbie; Aiken, Judd M. (November 2018).
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A 2018 study by scientists at the University of Alberta showed that humic acids can reduce
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571:
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The presence of carboxylate and phenolate groups gives the humic acids the ability to form
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527:
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that relatively small molecules also play a role. Humic substances account for 50 – 90% of
324:
284:"Brown humic acids" (BHA) are soluble in alkaline conditions independent of ionic strength
8:
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846:
791:
680:
560:
397:
260:
201:
192:
118:
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1532:(15th ed.). Columbus, Ohio: Pearson Education (published April 2017). p. 549.
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1325:
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958:
63:, meaning "soil, earth". Humic substances represent the major part of organic matter in
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2001:
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126:
2154:"Extraction of Fulvic Acid from Lignite and Characterization of Its Functional Groups"
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Tang, Chunyu; Li, Yuelei; Song, Jingpeng; Antonietti, Markus; Yang, Fan (2021-06-25).
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725:. A kind of artificial "lignohumate" can be directly produced from wood in this way.
351:
268:
114:
1980:"Humic Substances Their Influence on Creeping Bentgrass Growth and Stress Tolerance"
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966:
281:
So-called "gray humic acids" (GHA) are soluble in low-ionic-strength alkaline media.
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2013:
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to produce humic substances, reversing the natural process of coal formation under
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is soluble in water at neutral and alkaline pH, but insoluble at acidic pH < 2.
46:
2018:
1937:
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225:
84:
2301:
2234:"Humate in the upper Cretaceous Fruitland Formation in northwestern New Mexico"
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Humic acids are precipitated from this solution by adjusting the pH to 1 with
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1638:(15th ed.). Columbus: Pearson (published April 11, 2016). p. 554.
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Model structure of a humic acid, having a variety of components including
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153:
145:
1365:
MacCarthy, Patrick (November 2001). "The Principles of Humic Substances".
1202:
1109:
1092:
914:"In memoriam of Prof. F.J. Stevenson and the question of humic substances"
885:
728:
Agricultural litter can be turned into an artificial humic substance by a
338:
that diffuse easily through membranes, whereas all other colloids do not.
220:(1932), the polyphenol theory, and the sugar-amine condensation theory of
191:
Humic matter in isolation is the result of a chemical extraction from the
1438:
547:
122:
2056:"Artificial humic substances improve microbial activity for binding CO2"
1800:
1157:
1132:
393:
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change in conceptual understanding (a paradigm shift) appears imminent.
1093:"TPhysiological responses to humic substances as plant growth promoter"
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759:
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347:
185:
161:
1343:
1257:
Humic matter in soil and the environment: principles and controversies
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and, after subsequent addition of an acid, obtained an amorphous dark
49:
naturally formed during long-term decomposition and transformation of
1504:
989:"Source Materials for International Humic Substances Society Samples"
787:
645:
essential process for the uptake of otherwise insoluble iron oxides.
575:
555:. The molecules may form a supramolecular structure held together by
484:. Similar to clay, char and colloidal humus hold cation nutrients.
359:
307:; rather, it is a complex mixture of many different acids containing
233:
149:
88:
1585:
1290:
375:
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with ions that are commonly found in the environment creating humic
274:
The alcohol-soluble portion of humic fraction is, in general, named
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concentrations of organic matter, typically from concentrations of
505:
308:
237:
141:
76:
2118:
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from waste water. To this end, Yurishcheva et al. coated magnetic
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783:
743:
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591:
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335:
328:
205:
165:
50:
2352:
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2232:
Newcomer, Robert W.; Nybo, John P.; Newcomer, Jacob K. (2020).
790:, that are rich in humic acids. Humate has been mined from the
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229:
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30:
856:
851:
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747:
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509:
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249:
169:
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of humic molecules. All of them are constructed from similar
54:
19:
2002:"Soil humic acids degrade CWD prions and reduce infectivity"
1698:
184:
fewer polyaromatic units than humic substances derived from
1184:
Palanivell, P; Susilawati, K; Ahmed, OH; Majid, NM (2013).
866:
807:
779:
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304:
72:
68:
64:
24:
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1047:
1977:
1490:
1431:
Journal of the Chemical Society, Chemical Communications
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of wood, are valorized in the industrial fabrication of
487:
208:, then state the results in term of "humic substances".
2302:"Sorption of Pb2+ by magnetite coated with humic acids"
1605:. Advances in Agronomy. Vol. 75. pp. 57–134.
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594:
or industrial use can have a significant impact on the
1913:
2322:
1821:
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groups so that the mixture behaves functionally as a
2231:
2053:
1307:
732:. The resulting mixture can increase the content of
1571:
1276:
1097:
Chemical and Biological Technologies in Agriculture
918:
Chemical and Biological Technologies in Agriculture
1848:
1701:Humic Substances: Structures, Models and Functions
778:refers to geological materials, such as weathered
110:is part of humic acid that is soluble in ethanol.
2275:New Mexico Geological Society Special Publication
2241:New Mexico Geological Society Special Publication
1238:, Wiley & Sons, New York, 1994, pp. 188-210.
590:The presence of humic acid in water intended for
180:of humic and fulvic acids significantly overlap.
2359:
1683:Humus Chemistry: Genesis, Composition, Reactions
1236:Humus Chemistry: Genesis, Composition, Reactions
1950:
1133:"The contentious nature of soil organic matter"
878:
211:
2151:
1680:
1699:Ghabbour, E.A.; Davies, G. (Editors) (2001).
1130:
801:
586:Determination of humic acids in water samples
2329:. New York: Dover Publications. p. 62.
1899:: CS1 maint: multiple names: authors list (
402:introducing citations to additional sources
79:, and are important components of dissolved
2293:
2049:
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1978:Liu, Chunhua; Cooper, R. J. (August 1999).
1600:
905:
663:
469:
1126:
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911:
598:of that water and the success of chemical
57:, which in turn comes from the Latin word
2326:Ancient Egyptian Materials and Industries
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2136:
2095:
2027:
2017:
1965:10.2135/cropsci1998.0011183X003800060037x
1927:
1633:
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188:(which takes millions of years to form).
16:Major component of natural organic matter
2265:
2044:
517:
491:
392:Relevant discussion may be found on the
172:groups), albeit in varying proportions.
29:
18:
1743:
1117:
1091:Canellas P.L and Olivares F.L. (2014).
2360:
2353:International Humic Substances Society
2194:
1781:Environmental Science & Technology
1778:
1676:
1674:
1131:Lehmann, J.; Kleber, M. (2015-12-03).
298:International Humic Substances Society
1882:Ciencia interamericana: Volumes 24–27
1694:
1692:
1634:Weil, Ray R.; Brady, Nyle C. (2016).
1526:Weil, Ray R.; Brady, Nyle C. (2017).
626:
488:In traditional, base-soluble extracts
1314:Environmental Science and Technology
1043:
1041:
1007:
1005:
947:The Science of the Total Environment
369:
292:Humin is insoluble in dilute alkali.
1703:. Cambridge, U.K.: RSC publishing.
1671:
765:
106:is not soluble in water at any pH.
13:
1689:
1685:. New York: John Wiley & Sons.
1636:The Nature and Properties of Soils
1529:The Nature and Properties of Soils
1493:Land Degradation & Development
1259:. 2nd ed. Boca Ranton: CRC Press.
1022:10.1016/B978-0-12-811687-6.00004-3
899:Random House Dictionary Unabridged
817:
607:catchments in temperate climates.
362:, carbohydrates, and amino acids.
303:Extracted humic acid not a single
14:
2389:
2346:
1038:
1002:
683:), or by industrial synthesis of
603:supplies, especially from upland
2323:Lucas, A.; Harris, J.R. (1998).
1916:European Journal of Soil Biology
1849:Lapedes, Daniel N., ed. (1966).
1574:Canadian Journal of Soil Science
1387:10.1097/00010694-200111000-00003
1279:Canadian Journal of Soil Science
522:Model structure of a fulvic acid
385:relies largely or entirely on a
374:
243:
117:treated peat with a solution of
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2225:
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1993:
1971:
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1422:
1401:
1358:
1301:
1270:
1249:
1228:
967:10.1016/j.scitotenv.2017.02.059
862:Polycyclic aromatic hydrocarbon
102:is soluble in water at any pH.
2266:McLemore, Virginia T. (2020).
1177:
1084:
981:
938:
178:molecular weight distributions
34:Fulvic acid isolated from peat
1:
1611:10.1016/S0065-2113(02)75003-7
872:
2019:10.1371/journal.ppat.1007414
1938:10.1016/j.ejsobi.2006.06.004
1855:. McGraw-Hill. p. 428.
1836:10.1016/0043-1354(90)90038-8
1766:10.1016/0098-3004(94)90038-8
1190:The Scientific World Journal
474:
365:
212:Concepts of humic substances
45:) are coloured recalcitrant
7:
840:
794:of New Mexico for use as a
685:artificial humic substances
156:units and contain the same
83:(NOM) in lakes (especially
10:
2394:
2138:10.3390/separations8070096
2080:10.1016/j.isci.2021.102647
802:Technological applications
1746:Computers and Geosciences
1470:10.1016/j.aca.2012.01.027
931:10.1186/s40538-016-0076-2
746:(brown coal) may also be
23:Humic acid isolated from
2170:10.1021/acsomega.0c03388
1234:Stevenson, F.J. (1994).
734:dissolved organic matter
693:, a by-product from the
664:Anthropogenic production
617:dissolved organic carbon
482:cation exchange capacity
470:Chemical characteristics
1681:Stevenson F.J. (1994).
344:hydroxycarboxylic acids
319:or, occasionally, as a
1458:Analytica Chimica Acta
786:, or pore material in
523:
515:
81:natural organic matter
35:
27:
1110:10.1186/2196-5641-1-3
730:hydrothermal reaction
521:
495:
33:
22:
1601:Piccolo, A. (2002).
1439:10.1039/C39840001565
738:total organic carbon
701:where they serve as
613:total organic carbon
398:improve this article
131:Jöns Jakob Berzelius
2306:J. Biol. Phys. Chem
2164:(43): 27953–27961.
2072:2021iSci...24j2647T
1801:10.1021/es00108a003
1793:1983EnST...17...80O
1758:1994CG.....20..973T
1379:2001SoilS.166..738M
1326:2012EnST...46.9571M
1255:Tan, K. H. (2014).
1203:10.1155/2013/276235
1158:10.1038/nature16069
1149:2015Natur.528...60L
1016:. pp. 87–124.
959:2017ScTEn.586..807D
912:Piccolo A. (2016).
847:Black water (drink)
792:Fruitland Formation
782:beds (leonardite),
756:reducing conditions
715:mechanical strength
681:soil rehabilitation
561:van der Waals force
546:value around 4 for
354:, linear alcohols,
261:potassium hydroxide
202:soil organic matter
193:soil organic matter
119:potassium hydroxide
1729:has generic name (
711:water-cement ratio
709:, to decrease the
627:Ecological effects
567:, and CH-π bonds.
524:
516:
352:dicarboxylic acids
108:Hymatomelanic acid
36:
28:
2336:978-0-486-40446-2
1710:978-0-85404-811-3
1620:978-0-12-000793-6
1539:978-0-13-325448-8
1344:10.1021/es301107c
1320:(17): 9571–9576.
1062:10.1021/bm101488e
1050:Biomacromolecules
837:and humic acids.
463:
462:
448:
413:"Humic substance"
269:hydrochloric acid
226:dead plant matter
158:functional groups
115:Franz Karl Achard
47:organic compounds
2385:
2341:
2340:
2320:
2314:
2313:
2297:
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2222:
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2219:
2213:
2207:. Archived from
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2142:
2140:
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2110:
2109:
2099:
2051:
2042:
2041:
2031:
2021:
2012:(11): e1007414.
1997:
1991:
1990:
1987:TurfGrass Trends
1984:
1975:
1969:
1968:
1948:
1942:
1941:
1931:
1911:
1905:
1904:
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1890:
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1516:
1505:10.1002/ldr.2989
1499:(6): 1792–1805.
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1481:
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1420:
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1081:
1056:(4): 1187–1199.
1045:
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1000:
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997:
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978:
942:
936:
935:
933:
909:
903:
902:
893:
892:
882:
833:reinforced with
772:economic geology
766:Economic geology
707:superplasticizer
559:forces, such as
458:
455:
449:
447:
406:
378:
370:
257:sodium hydroxide
85:dystrophic lakes
39:Humic substances
2393:
2392:
2388:
2387:
2386:
2384:
2383:
2382:
2358:
2357:
2349:
2344:
2337:
2321:
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1929:10.1.1.486.2522
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1752:(6): 973–1023.
1742:
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1373:(11): 738–751.
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1291:10.4141/s00-075
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884:
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820:
818:Ancient masonry
804:
768:
740:(TOC) in soil.
695:sulfite pulping
691:Lignosulfonates
666:
629:
588:
582:of metal ions.
580:bioavailability
545:
490:
477:
472:
459:
453:
450:
407:
405:
391:
379:
368:
246:
214:
176:acid. However,
87:), rivers, and
17:
12:
11:
5:
2391:
2381:
2380:
2378:Soil chemistry
2375:
2370:
2356:
2355:
2348:
2347:External links
2345:
2343:
2342:
2335:
2315:
2292:
2258:
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2144:
2111:
2043:
2006:PLOS Pathogens
1992:
1970:
1943:
1906:
1871:
1862:978-0070452657
1861:
1841:
1824:Water Research
1814:
1771:
1736:
1727:|author2=
1709:
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1590:
1580:(3): 285–297,
1564:
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1433:(23): 1565–6.
1421:
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1335:10.1.1.698.270
1300:
1285:(3): 285–297,
1269:
1248:
1227:
1176:
1143:(7580): 60–8.
1116:
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896:Dictionary.com
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796:soil amendment
767:
764:
705:, or concrete
665:
662:
642:soil fertility
628:
625:
587:
584:
553:charge density
543:
489:
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468:
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396:. Please help
382:
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367:
364:
356:phenolic acids
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2373:Organic acids
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827:ancient Egypt
824:
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812:nanoparticles
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703:water reducer
700:
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425:
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418:
415: –
414:
410:
409:Find sources:
403:
399:
395:
389:
388:
387:single source
383:This article
381:
377:
372:
371:
363:
361:
357:
353:
349:
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321:tribasic acid
318:
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244:Fractionation
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2295:
2283:. Retrieved
2278:
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2249:. Retrieved
2244:
2240:
2227:
2216:. Retrieved
2209:the original
2196:
2161:
2157:
2147:
2128:
2124:
2114:
2063:
2059:
2009:
2005:
1995:
1986:
1973:
1956:
1953:Crop Science
1952:
1946:
1919:
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1823:
1817:
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1784:
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1367:Soil Science
1366:
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983:
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940:
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894:– via
889:. Retrieved
880:
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805:
775:
769:
742:
727:
689:
684:
667:
655:
651:
647:
630:
621:
609:
600:disinfection
596:treatability
589:
569:
557:non-covalent
530:nuclei with
525:
478:
464:
454:October 2021
451:
441:
434:
427:
420:
408:
384:
340:
333:
317:dibasic acid
302:
295:
275:
254:
247:
215:
198:
190:
182:
174:
154:carbohydrate
146:polyaromatic
135:
112:
107:
103:
99:
95:
93:
58:
42:
38:
37:
2312:(2): 61–68.
2125:Separations
1959:(6): 1639.
1922:: S65–S69.
953:: 807–816.
825:finds that
774:, the term
548:protonation
348:fatty acids
123:precipitate
100:Fulvic acid
2368:Composting
2362:Categories
2285:26 October
2251:26 October
2218:2022-03-18
1830:(6): 797.
1654:2016008568
1548:2016008568
1416:vet servis
1265:1482234459
1244:0471594741
1196:: 276235.
891:2024-07-20
873:References
823:Archeology
788:sandstones
760:leonardite
736:(DOM) and
719:hydrolysis
675:or adding
670:composting
536:carboxylic
424:newspapers
360:terpenoids
276:ulmic acid
228:, such as
186:leonardite
162:carboxylic
96:humic acid
2158:ACS Omega
2131:(7): 96.
2088:2589-0042
1924:CiteSeerX
1895:cite book
1719:cite book
1662:942464649
1556:936004363
1513:135445097
1464:: 77–90.
1395:101148229
1330:CiteSeerX
831:mudbricks
723:oxidation
615:(TOC) or
572:complexes
475:In nature
394:talk page
366:Criticism
325:complexes
313:phenolate
234:cellulose
150:aliphatic
138:continuum
129:water by
89:sea water
77:sediments
2188:33163778
2106:34466779
2060:iScience
2038:30496301
1809:22295957
1478:22365124
1352:22834642
1222:24319353
1167:26595271
1078:45333263
1070:21361272
975:28214121
841:See also
748:oxidized
699:concrete
638:nutrient
532:phenolic
528:aromatic
513:moieties
506:catechol
336:colloids
329:colloids
309:carboxyl
238:charcoal
222:Maillard
166:phenolic
160:(mainly
142:aromatic
2281:: 53–63
2247:: 41–46
2179:7643152
2097:8387571
2068:Bibcode
2029:6264147
1789:Bibcode
1754:Bibcode
1375:Bibcode
1322:Bibcode
1213:3836416
1145:Bibcode
994:22 July
955:Bibcode
886:"Humus"
784:mudrock
744:Lignite
677:biochar
619:(DOC).
592:potable
576:chelate
498:quinone
438:scholar
218:Waksman
206:compost
51:biomass
2333:
2186:
2176:
2104:
2094:
2086:
2036:
2026:
1926:
1859:
1807:
1707:
1660:
1652:
1642:
1617:
1554:
1546:
1536:
1511:
1476:
1393:
1350:
1332:
1263:
1242:
1220:
1210:
1165:
1137:Nature
1076:
1068:
1028:
973:
776:humate
752:anoxic
673:lignin
634:Liebig
508:, and
502:phenol
440:
433:
426:
419:
411:
230:lignin
168:, and
152:, and
127:spring
75:, and
2271:(PDF)
2237:(PDF)
2212:(PDF)
2205:(PDF)
1983:(PDF)
1509:S2CID
1412:(PDF)
1391:S2CID
1103:: 3.
1074:S2CID
857:Humus
852:Humin
835:straw
829:used
679:(see
658:prion
605:peaty
510:sugar
445:JSTOR
431:books
250:humin
170:ester
104:Humin
60:humus
55:humus
2331:ISBN
2287:2020
2253:2020
2184:PMID
2102:PMID
2084:ISSN
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