Humus, Humin, Humic and Hummus
America was only ten years a nation when humic acid was first extracted from a peat bog by a German scientist in 1786. The rich, dark organic matter from which it was extracted was of much concern to early agriculture as it was originally believed to be the primary reason for plant growth. Since then, tens of thousands of research papers have been written trying to explain the chemistry and functions of organic acids.
Unfortunately, researching organic acids can be much like trying to compare melting snowflakes. Each molecule of organic acid can be different, constantly changing and difficult to measure. However, after over 200 years of research, a few key distinctions can now be made, which helps describe the ideal organic acids for agriculture.
Today, humic substances can be broken down to three major fractions: humin, humic acids and fulvic acids.
- Humin is the largest fraction of molecules and can be up to 1,000 times the size of humic acids. Humin is very stable in the soil, insoluble and not as active in complexing nutrients. The primary benefits of humin are increasing water-holding capacity and improving soil structure.
- Humic acids are the medium-sized molecules of humic substances and are much smaller than humin but with more cumulative surface area, allowing a product like Hydra-Hume® to perform at a higher level. The increase in surface area and solubility of humic acids greatly increase its activity in the soil and its ability to complex many different types of nutrients. Humic acids will also increase water-holding capacity and structure of soil. Since humic acid is not as stable as humin, it will degrade to become fulvic acid.
- Fulvic acids are the smallest of these three molecules and is the most water soluble over a wide pH range. Due to their reactivity and solubility, fulvic acids are the most highly “plant active” and
also the least stable. Fortunately, due to their small size they are able to enter plant roots and leaf tissue while carrying complexed nutrients.
The best sources of humic substances are from leonardite ore and contain primarily humic acids with a high fraction of fulvic acids (while delicious hummus still needs more research). The quality and value of any product depends on many different factors and a good humic material can be destroyed by improper mining or processing. Thus, not all commercially marketed humic substances are equal in quality. The real test of any humic product is in the field with an open mind.
- Chad Lessard, Agronomist, Southern San Joaquin Valley