Humic & Fulvic acids based fettilizers, mainly deriving from Leonardite, are increasingly popular in organic farming of course but also in conventional outdoors horticulture, greenhouse cropping and even in the broad acre sector. Now available from a bunch of suppliers in liquid, powder or granular form, they are applied as soil conditioners and plant growth stimulators.

A number of natural sources may be considered as raw material for the manufacture of humic acid/fulvic acid based commercial specialities. However, it clearly transpires that Leonardite is the best source material.

The difference between Leonardite and other sources of humic acids lies in the fact that Leonardite is extremely bioactive through its molecular structure. This biological activity is said to be about five times stronger than other humic matter.

A variety of commercial products exist in the market now, from the powder/granulated Leonardite or humic acid concentrate all the way to powder, soluble crystalline or liquid K-humates, Amm-humates, Na-Humates and even Boron and Magnesium humates, but also Fulvic acid concentrates, Potassium Fulvates, Sodium Fulvates, etc. The potential buyer has a broad choice of offerings.

Soil Organic Matter is frequently said to consist of humic substances and non-humic substances.

Non-humic substances are all those materials that can be placed in one of the categories of discrete compounds such as sugars, amino acids, fats and so on.

Humic substances are the other, unidentifiable components. Generally, humic substances are considered as a series of relatively high-molecular-weight, brown to black coloured substances formed by secondary synthesis reactions.

Humic acids are indeed thought to be complex aromatic macromolecules with amino acids, amino sugars, and peptides, aliphatic compounds involved in linkages between the aromatic

groups. The hypothetical structure for humic acid contains free and bound phenolic OH groups, quinone structures, nitrogen and oxygen as bridge units and COOH groups variously placed on aromatic rings

Humic substances not only impact on the physical,chemical and biological properties of soils, they also have a direct influence on plants and crops. Indeed, some recent studies have shown that humic substances contain auxin orstimulate the activity of auxin-like molecules. They influence the uptake of ions by plants and they stimulate plant growth with efficiency comparable to auxin (AIA).