THE EFFECTS OF HUMIC ACIDS ON ALGAE GROWTH
Literature Review and References

I have gathered this information on the effects of humic acids on algae. It backs up what we are seeing with New Mexico humate; it is capable of enhancing algae production and quality at a very low cost. Only 80-100ppm humic acids are required to greatly increase pigment development and growth. New Mexico humate has the best ratio of low to high molecular weight humic substances and natural surfactants which why it is effective at a low rate.

Freeman states that "It had been observed throughout previous growth tests that one of the principal effects of coal-derived humus was a darker pigmentation in the treated plants than in the control plants. A convenient way to study pigment development on a quantitative basis is with algal cultures. When grown in the dark under normal nutrient conditions with 1 percent glucose, these single-celled plants develop green pigmentation in proportion to the amount of available iron. They continue to respire and do not die; most higher plants will die when deprived of light.

To study the effect of coal-derived humus on pigment development, a water-soluble humic acid (WSHA) fraction of naturally oxidized lignite (leonardite) was prepared. Preparation of WSHA is described in a previous publication (Freeman & Fowkes, 1968). This material was added to a standard nutrient solution in concentrations of 1, 10, and 100 parts per million (ppm). Each nutrient was sterilized, then inoculated with a wild strain of Chlorella vulgaris, a common single-celled alga. After 90 hours of growing in the dark, the algal cultures had produced pigment roughly in proportion to the concentration of WSHA in the nutrient medium (Brown, 1969).

Pigment production is often correlative to iron availability, for example, chlorosis (yellowing due to lack of green pigment) can be induced by using iron-free growth media. As a direct measure of iron uptake, the algal cultures were supplied with a tracer, isotope Fe59. The amount of iron taken up by the Chlorella in the various cultures could then be determined by spinning out the cells and measuring the residual radioactivity of the nutrient. The amount of Fe59 taken up by the plant cells was in direct proportion to the WSHA concentration in the nutrient.

This made it increasingly clear that at least one of the main functions of WSHA in promoting plant growth was an ability to supply iron to the plant. In the case of Chlorella, it might also be assumed that, since a close correlation exists between pigment production and iron uptake, the two go hand in hand. Further evidence is necessary, however, to determine the extent of this effect on higher plants." Freeman P.G. (1970) The use of lignite products as plant growth stimulants. BuMines Rept. of Inv. 8471, p.153-154.


Lee and Bartlett reported that "Humic substances also stimulated the growth of algae. The optimum concentration, however, was much higher (60ppm C) than in the case of corn (5ppm C). It is hard to explain the reasons behind the differing optimum concentrations. But, the results of Fernandez (1986), Kononova (1961), and Poapst et.al. (1970) demonstrated differences among plants in optimum concentrations of humic acid for the highest stimulating effects.

Different humic substances also produced different effects on the growth of algae. Fulvic acids were expected to show greater effects on algae growth than humic acids because of the higher concentration of functional groups in fulvic acids (Schnitzer and Kahn, 1972). But, the results were similar. The mixture of high and low molecular weight humic substances seemed to be the best for stimulation of algal growth. More investigation is needed to explain the differing effects of different humic substances.

It is interesting that the effects of soil treatments were much less than the treatments with humic substances. This suggests that it might be possible, under natural conditions, to increase algae populations by the applications of humic extracts. Increases in populations of N-fixing algae in paddy fields could increase the N content of the soil. Direct stimulation effects of humic acids on rice plants also would be expected. On the other hand, humic substances from polluting sewage, manure, or from erosion of top soil, may stimulate undesirable algal growth in streams, lakes, and other bodies of water." Lee Y.S. and Bartlett R.J. (1976). Stimulation of plant growth by humic substances. Soil Sci.Soc.Am.
J.40,879.

"Zientara (1983) observed that Na-humate induced changes in electrical resistance between the interior cell on the alga Nitellopis obtusa and the exterior. He proposed that the primary action of humate on plants consists of an effect on the permeability of the plasmalemma, especially with respect to the electrogenic proton pump." Visser S.A. (1985). Effects of humic substances on plant growth. p.112

Effect on salt concentration and salt balance in the environment
"Humic acids, because of their ion exchange properties, are able to affect the concentration and availability of salts in the environment. By this phenomenon they may be able to prevent toxic symptoms in plants, normally occurring as a result of high salt concentrations in the environment (Badura, 1965; Hernando et al., 1970; Jurajda, 1974).

Ion exchange behavior of humic acids will also facilitate the exchange of ions between the protoplasmic membrane and the environment, and will allow plant growth within a wider pH range (Badura, 1965).

Effect on cell membrane permeability
A great many authors have expressed the opinion that humic substances affect the permeability of cellular membranes (Lieske, 1932; Niklewski, 1933, 1934; Blagowestschenski & Prosorowskaja, 1934, 1935; Khristeva, 1951; Chaminade & Blanchet, 1951, 1952, 1953; Khristeva, 1953; Chaminade, 1956; Lee & Bartlett, 1976). This opinion is based, in particular, on the observed increase in nutrient uptake by plants when in the presence of humic substances.

Blagowestschenski & Prosorowskaja (1935) demonstrated that humic acids, present at 1000 mg l-1, increased transport of glucose across the membrane of cells of onion (Allium cepa), sunflower (Helianthus annuus) and sugar beet (Beta vulgaris) ." Visser S.A. (1985). Effects of humic substances on plant growth. p.110-111.




LITERATURE CITED AND REFERENCES

Badura L. (1965). On the mechanism of the stimulating influence of Na-humate upon the process of alcoholic fermentation and multiplication of yeasts. Acta Soc.Bot.Pol.,34,287-328.

Bhardwaj K.K.R. and Gaur A.C. (1970). The effect of humic and fulvic acids on the growth and efficiency of nitrogen fixation of Azotobacter chroococcum. Folia Michrobiol.,15,367.

Bhardwaj K.K. and Gaur A.C. (1971). Studies on the growth stimulating action of humic acid on bacteria. Zentralbl. Bakteriol.Parasitenkd.Infektionskr.Hyg.Abt.2,126,694-699.

Blagowestschenski A.W. and Prosorowskaja A.A. (1934).Uber den einfluss der huminsaure auf die aufnahme der mineralsalzen durch die pflanzen. Biochem.Z.,274,341-345.

Blagowestschenski A.W. and Prosorowskaja A.A. (1935). Zur frage des einflusses der huminsaure auf die assimilation der plfanzen. Biochem.Z.,282,99-103.

Bottomley W.B. (1917). Some effects of organic growth-promoting substances (auximones) on the growth of Lemma Minor in mineral culture solutions. Proc.R.Soc.Lond.Ser.B.,89,481-487.

Bottomley W. (1920). The effect of organic mater on the growth of
various plants in cluture solutions. Ann.Bot.(Lond.),34,365.
Brown C.J. (1969). Effect of coal derived humic acid on growth and
chlorophyll content of Chlorella Vulgaris. M.S. Thesis, U. of
North Dakota, 35pp.

Cacco G. and Dell'Agnola G. (1984). Plant growth regulator activity of soluble humic complexes. Can.J.Soil Sci.,64,228.

Chaminade R. (1956). Action de l'acide humique sur le development et la nutrition minerale des vegetaux. Trans.6th Intern.Cong.Soil Sci.,4,443-448.

Chaminade R. and Blanchet R. (1951). Action de l'humus colloidal sur la nutrition minerale des vegetaux. C.R.Acad.Sci. (Paris), 233,1486-1492.

Chaminade R. and Blanchet R. (1952).Influence de l'humus sur la nutrition minerale de la plante dans le sol. C.R.Acad.Sci. (Paris), 234,878-879.

Chaminade R. and Blanchet R. (1953). Mecanisme de l'action stimulante de l'humus sur la nutrition minerale des vegetaux. C.R.Acad.Sci.(Paris), 237,1768-1770.

Fernandez V.H. (1968) The action of humic acid of different
sources on the development of plants and their effect on
increasing concentration of the nutrient solution. p.805-856.
In Study week on organic matter and soil fertility. North
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Freeman P.G. and Fowkes W.W. (1968). Coal-derived humus: plant
growth effects. BuMines Rept. of Inv. 7203, 16pp.

Hernando V., Sanchez Conde M.P. and Ortega B.C. (1970). Correlacion entre sintomas de toxicidad relaciones ionicas de la planta de maiz y nivelles de acido humico aplicado a su cultivo. An.Edafol.Agrobiol., 29,657-672.

Hoeffner S.L. and Manahan S.E. (1980). Influence of coal humic acid on the growth of Chlorella vulgaris algae. J.Environ. Sci.Eng.,15,149-161.

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Kaushik B.D., Roychoudhury P. and Venkataraman G.S. (1980). Effect
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Kononova M.M. (1961). Soil organic matter. Pergamon Press, London.

Khristeva L.A. (1951). The role of humic acid in plant nutrition and humus fertilizers. Tr.Pochv.Inst.Im V V Dokuchaeva. Nauk.SSR.38,108-184.

Khristeva L.A. (1953). The participation of humic acids and other organic substances in the nutrition of higher plants. Pochvivedenie, 10,46-59.

Lee Y.S. and Bartlett R.J. (1976). Stimulation of plant growth by
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Niklewski B. (1934). Uber den enfluss von kolloidsubstanzen auf die aufnahmefahigkeit von magnesium und ammoniumchlorid durch die wrzeln der pflanzen. Biochem.Z., 271,111-122.

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I believe the best way to find out what New Mexico humates will do with algae or aquaculture is to try a small scale flask test in an incubator with 80-100ppm humate and control flask. This is the best way to judge the value of the product, as others have done.

Robert H. Faust Ph.D.