Humin

Although the chemical structure of the macromolecules is not largely secured, yet the base structure can be seen. Humic substances consist of cores, bridges and reactive side groups. As nuclei occur frequently benzene, indole, pyrrole, naphthalene, pyridine, quinoline, or furan. As bridges act primarily oxygen, nitrogen, carbon, simple hydrocarbons or secondary carboxamides. Wherein the side groups is essentially carboxyl, carbonyl, methoxy, amino and hydroxy groups are involved. In terms of their chemical structure, humic substances can be described only statistically, as they form a to season changing from place to place and from season mixture.

Classification

We distinguish:

• Humine: insoluble substances
• Fulvic acids: are readily soluble in acidic and basic conditions
• Humic acids: are soluble in a basic medium and serve as the binding of heavy metals

Fraction in soils

• Agricultural Soils: 1-2 %
• Black Earth: 2-7 %
• Pastures: 10 %
• Marshy soil: 10-20%

Ecological Characteristics

Food source

Humic substances are difficult to degrade due to their high molecular character. The reduction is generally carried out cometabolically (see priming effect ), and under aerobic conditions. Cometabolically means that the humic substances are not used as the sole carbon source, but only to the supply of nutrients (especially nitrogen, sulfur, phosphorus) can be used. Humic substances -degrading microorganisms include actinomycetes, Streptomyces, Pseudomonas, and fungi, such as mushrooms or toadstools or Penicillium (see penicillin).

In laboratory tests, often could be a promotion of plant growth by humic substances are observed. This is attributed to the following causes:

• High cation exchange capacity of humic substances ( good availability of cations)
• Physiological changes - Humic substances have a hormone-like effect ( which is not clear whether the humic substances even have a hormone- like or the hormones are adsorbed on their surfaces )
• Supporting the inclusion of micro- nutrients, for example iron and copper,

Effect on soil enzymes

Humic substances inhibit the activity of soil enzymes by competitive or allosteric inhibition. Thus, the turnover of substrates is delayed.

Studies on the nematode Caenorhabditis elegans have shown that humic substances exert a chemical stress, but which can have positive effects on the body if it is not too strong. The humic some abandoned animals acquire multiple stress resistance that can even prolong life.

In embryos and young fish, such as those of the swordtail, improved during addition of the synthetic Huminstoffpräparates HS 1500, the weight gain and the growth in size. In addition, the study populations developed from predominantly female juveniles, so that it can be assumed, an estrogenic potential of humic substances.