Humics and fulvics- essentials for plant and soil health

Plant health and soil fertility are directly impacted by beneficial soil organisms, such as algae, bacteria, fungi, mycorrhizae, and nematodes. As an example, it is bacteria that release organic acids which play a role in the break down of the mineral elements in the soil. There are bacteria that are also responsible for releasing sugar based compounds that help to create soil crumbs, giving the soil a desirable structure. Mycorrhizae assist with the uptake of water and trace minerals in the root zone.

But these soil organisms are unable to capture the energy from the sun directly, due to their lack of photosynthetic functions. They therefore must obtain their energy by taking up residual carbon that is found in the soil. It is the energy that is stored within the carbon bonds of humic substances that sustains these organisms and their metabolic processes. A healthy, fertile soil sustains the billions of microscopic life forms only when it contains sufficient carbon containing compounds. Reduce the available carbon in the soil and you reduce the energy source of these soil organisms. Reduce the soil organisms, and you reduce the available nutrients and organic compounds that crucial plant health and growth depend on.

Humus, the degraded form of organic material, is fairly common and found in almost all soils. Generally, humus distinguishes itself from organic matter because all of the sugar, fiber, cellulose, lignin, gums and proteins have been decomposed, the material is resistant to further decomposition and the original or parent material can no longer be identified. This decay process broke the organic matter down into reasonably simple molecules, which were then acted upon by the soil microbiology and built up into very complex, larger carbon chains. At this point, it is called humic substance. These larger carbon chains are very stable in the soil, and can last for many years.

The erosion of soil carbon and humus however is all too common and can be found in the modern agricultural practice of reliance on synthetic salt and ammonia based fertilizers. Unfortunately, through the continued use of NPK fertilizers, there is little balance given to the carbon that is required by the soil organisms to properly process the increased nitrogen content, and the humic substance levels are reduced. In addition, the continuous ploughing and rototilling of soils exposes any organic matter to the oxygen, which then negatively impacts the transformation of humus into viable humic substances.

The addition of humic substance to all soils is important, even on organic farms where these substances have not been depleted, because it acts as a stimulant for the soil microbiology and worms. Humic substance levels can be brought back through the use of cover crops, green manure, grazing and through the addition of a good quality compost. They are therefore, essential to all organic or sustainable approaches to plant production.

Humic acids, a derivative of humic substances is brown to black in colour and have a higher molecular weight, which means that the structure of their molecules are larger. Consequently, they are not able to be absorbed into a plant’s roots or leaves, unlike fulvic acid. This is why humic acids are more often dry broadcast onto soils and used in this capacity as a soil conditioner, as well as for feeding the soil microbes.

Humic substances can be derived from carbon containing minerals such as brown coals, low grade lignites, and leonardites, and make good fertilizer ingredients. That said, the quality and value of any one mined humate or humic acid product depends on many different factors. A good humic material can be destroyed by improper mining or processing. Thus not all commercially marketed humic substances are equal in quality. This is even more so with fluvic acids, which are the most active of the humic group, as they need to be processed from their humic acid origins.

Fulvic acid is something of a derivative or by product of humic substances and is golden in colour. Because of the transformative action of the soil microbes in the creation of fluvics, they are considered to be the most biologically complex organic compound on earth. As fluvic acid has the lowest molecular weight portion of the humic substance, they are therefore much more able to penetrate the leaf and root cell structure than the larger molecules of the humic substances. Fulvic acid has the unique and powerful benefit of being able to ‘pull’ along with it over 60 mineral and trace elements as it crosses over the cell barriers. They literally are small enough to pass through the cell walls of the root, stem and leaves, carrying their rich mineral bounty with them and delivering them into the metabolic heart of the cellular structure where they are needed. This increased nutrient availability stimulates the metabolism of the plant, increases enzymatic activity and acts as a catalyst to the plant respiration, aiding chlorophyll synthesis.

Fulvic acid is best used as a foliar, but also works nicely as a root drench. It is a very effective tool for increasing nutrient efficiency and uptake, increasing lateral root growth, building plant immunity and also stimulating microbes.