Humic and fulvic acids in fertilizers: inspired by nature

As a pillar of fertility, the organic substance of the soil, naturally present or added with fertilization, is one of the topics that we most love to discuss in our studies.

Speaking generically of soil organic matter is an understatement, considering the fact that there are different forms, deriving from the balance between different processes, and that they influence in a variable way the chemical-physical and biological characteristics of cultivated land, as well as the latter’s ability to nourish plants.

Stable organic matter, namely humus, contains humic substances — humic, fulvic and amino acids — of great interest in agriculture but also in ecology, with a view to safeguarding and restoring soil quality.

But let’s go in order.

As we explain in this article and in our podcast “Fertile Ground”, the organic substance present in a soil at a given time is always a mix of different components.

There is living biomass, consisting of all the micro and mesofauna that inhabits that soil, and there is dead biomass. The latter consists both of recently deposed animal and plant residues that have not yet decomposed, and partially of decomposing residues, due to the action of microorganisms of various kinds.

Finally, there is a stable component – or difficult to modify – component of the organic substance, humus, deriving from the humification process, also attributable to the action of microorganisms. Humus includes more or less large and complex molecules, among which umine, humic acids and fulvic acids stand out.

In addition to humification, mineralization (i.e. decomposition) and the formation of complexes between organic fraction and mineral fraction regulate the balance between the different types of organic matter present in the soil. All these processes are influenced, in addition to the composition of the soil microbiota, by the temperature, humidity and oxygenation conditions of the soil itself, as well as by the agricultural practices adopted. Intense processing, for example, favors the mineralization of the organic substance, while the techniques of conservative and regenerative agriculture slow it down, encouraging humification.

Huma. It is the heaviest and most complex fraction of humic substances. It has limited solubility and contributes to soil stability, improving its structure and water retention capacity.

Humic acids. These are water-soluble acids at high pH, known for their ability to exchange ions, improving the availability of nutrients for plants. They also have chelating properties, which help to immobilize heavy metals and pesticide residues that may be present in the soil.

Fulvic acids. Smaller and lighter acids than humic ones, and soluble in water at any pH. Together with humic acids, they contribute decisively to the delivery of nutrients in the circulating solution and to their availability for absorption by the roots.

Humic substances therefore influence the chemical properties of the soil, the physical ones (contributing to the structure and porosity) and biological ones, promoting biodiversity, thanks to their direct and indirect stimulating action on the microflora.

Several researchers have also demonstrated that humic substances improve the growth of roots, leaves and sprouts, promote the germination of seeds of different crops and stimulate primary and secondary metabolism underlying tolerance to environmental stresses such as salinity, drought and extreme temperatures.

An intense research activity in recent years has deepened the characteristics, benefits and practical applications of humic and fulvic acids in agriculture, as can be seen from the extensive literature available on the subject.

Just to give a few recent examples: the application of fulvic acids improves the germination performance of rice in conditions of scarce availability of phosphorus but also under conditions of salt stress, as well as increases yields in the cultivation of garlic.

While here we talk about the possibility of producing spinach with a high iodine content (and therefore with an interesting nutraceutical value) by fertigating the crop with products containing iodine chelated by humic and fulvic acids, this other publication demonstrated that in the cultivation of peppers, fertilization with humic and fulvic acids improves the antioxidant properties of the product.

As is well known, the wide-scale application of intensive agricultural practices and the current climate changes have severely depleted cultivated land of stable organic matter, with the consequent loss of all the agronomic and ecological benefits guaranteed by an adequate content.

Consequently, today’s agriculture benefits in a concrete way from the use of organic and organo-mineral fertilizers capable, among other things, of providing humic substances to the soil. Distribution by foliar route is also useful, since in this case humic and fulvic acids improve the absorption and circulation of nutrients within the plant.

All the organic matrices used in the formulation of Agribios fertilizers are highly humidified, thanks to the long process of slow natural fermentation that precedes their use and which favours the increase of their content in humic and fulvic acids.