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"Humic substances" is an umbrella term covering humic acid, fulvic acid and humin, which differ in solubility. By definition, humic acid (HA) is soluble in water at neutral and alkaline pH, but insoluble at acidic pH < 2. Fulvic acid (FA) is soluble in water at any pH. Humin is not soluble in water at any pH.
Potassium humate is used in agriculture as a fertilizer additive to increase the efficiency of fertilizers especially nitrogen- and phosphorus-based fertilizer inputs. Other salts of humic acid are manufactured, mainly sodium humate, which is used in animal health supplements. It also can be used in aquaculture.
Humic substances are classified into three genera based on their solubility in acids and alkalis, and also according to their stability: Fulvic acid is the genus that contains the matter that has the lowest molecular weight, is soluble in acids and alkalis, and is susceptible to microbial action.
Due to their very complex molecular structure, humic substances, including humin, do not correspond to pure substances but consist of a mixture of many compounds that remain very difficult to characterize even using modern analytical techniques.
The composition of humus varies with that of primary (plant) materials and secondary microbial and animal products. The decomposition rate of the different compounds will affect the composition of the humus. [13] It is difficult to define humus precisely because it is a very complex substance which is still not fully understood.
The formation of a humic lakes via organic runoff has a dramatic effect on the lake ecosystem. Increases in the lake’s acidity make it difficult for fish and other organisms to proliferate. The quality of the lake for use as drinking water also decreases as the carbon concentration and acidity increase.
The microbiota and enzymes present in compost extracts also have a suppressive effect on fungal plant pathogens. [24] Compost is a good source of biocontrol agents like B. subtilis, B. licheniformis, and P. chrysogenum that fight plant pathogens. [23] Sterilizing the compost, compost tea, or compost extracts reduces the effect of pathogen ...
The International Humic Substances Society was founded in Denver, Colorado, USA, on September 11, 1981 by scientists who saw a need for a society to bring together scientists in the coal, soil, and water with interest in humic substances, and to provide opportunities for them to exchange ideas .