Organo-mineral fertilizers: what are they and why are they useful

The advantages deriving from the use of organo-mineral fertilizers in agriculture have been known for decades and well documented in the Bibliography, as well as demonstrated “in the field” by agricultural practice.

Today, however, organo-mineral fertilization, by virtue of the high efficiency that characterizes it, takes on a greater meaning and importance in light of two situations, the first is of an extremely agronomic nature (excessive exploitation of agricultural land, with its impoverishment and destructuring) and the second is of a cyclical and geopolitical nature, in essence  Europe’s dependence on Russia (and Belarus) for the supply of raw materials intended for the formulation of mineral and organo-mineral fertilizers (urea, ammonium nitrate, potassium, phosphorus).

The tensions linked to Russia’s invasion of Ukraine, the consequent sanctions imposed by the EU on the invading country and the  repeatedly feared restrictions on fertilizer exports by Vladimir Putin require a review of crop fertilization strategies, which aims to maximize the effectiveness of this practice and limit the loss of the fertilizer units distributed to a minimum.

As is well known, an agricultural plot of land can never lack organic matter, even though the portion of it in the soil considered optimal varies for the different crops. The presence of organic matter (in particular of its “stable” fraction, see below) is in fact due to a fundamental physical characteristic of the soils, the structure, which guarantees an adequate division of the layer explored by the roots into full spaces and empty spaces. In a balanced soil, in the “empty” spaces we find alternatively air (and therefore oxygen, essential for roots to breathe but also for the entire telluric fauna) and circulating solution, in which the nutrients released from the organic and inorganic fractions of the soil are dissolved. In fact, the organic matter contains from 20 to 80% of the Phosphorus present in the soil and more than 90% of the total Sulfur, as well as being a precious source of Nitrogen.

An inadequate supply of organic matter, combined with the trampling of the land by heavy agricultural vehicles, leads to the compaction of the soil, which becomes therefore asphyxiated and often prone to waterlogging.

Decades of agriculture in which attention has not always been adequately paid to safeguarding the physical and biological fertility of the land, since the main concern was to replenish the removal of elements absorbed by crops, through mineral fertilization, have led to a widespread fatigue of the cultivated land, increased by the mineralization of organic matter (with the release of CO₂ into the atmosphere), promoted by frequent processing and ongoing climate change.

The fertilization of cultivated plants is based on the use of solid or liquid products, belonging to three categories. Legislative Decree 75/2010 contains the following definitions:

Mineral fertilizer: a fertilizer in which declared nutrients are present in the form of mineral compounds obtained by extraction or industrial physical and chemical processes; calcium cyanamide and urea and their condensation and association products, as well as fertilizers containing chelated or complex microelements, can be classified as mineral fertilizers by convention.

Organic fertilizer: a fertilizer derived from organic materials of animal or vegetable origin, consisting of organic compounds to which the main elements of fertility are chemically linked in organic form, or in any case, form an integral part of the matrix.

Organo-mineral fertilizer: a fertilizer obtained by the reaction or mixture of one or more organic fertilizers or one or more organic matrices, authorized for this purpose in Annex 5, or both, with one or more organic fertilizers.

The nutrition of cultivated plants is better in fertile soil. An obvious fact? Not really. Even the best fertilizer turns out to be ineffective in tired soil. And the fatigue of a soil is measured mainly by the reduction of its biological fertility. The latter is closely linked to the quantity and variety (biodiversity) of living organisms that live in it.

The role of “living” organic matter — in particular of microorganisms such as fungi, bacteria and algae — in improving the nutritional and health status of plants through different mechanisms is now widely proven. However, we must remember that it is precisely the presence of “dead” organic matter that stimulates the proliferation of telluric microflora, thanks to the improvement of the physical conditions of the soil and the supply of nutrients.

The use of organo-mineral fertilizers, therefore, makes it possible to contribute favourably to this virtuous balance, but not only that. Thanks to the presence of the organic fraction, the nutrients provided are less prone to losses due to washout, evaporation, retrogradation and fixation and face slower, gradual and prolonged transfers over time. The result is a greater efficiency of the fertilization operation, with beneficial effects on the environment and on the company’s budget.

Talking generically about organic matter is not enough to explain the role it plays in agricultural lands. In fact, a distinction must be made between labile and stable organic matter.

The labile one consists essentially of simple molecules (sugars, peptides, proteins, nucleic acids…) free in the soil, while the stable one from the so-called humus, is the result of reprocessing, polymerization and condensation processes of simple organic compounds implemented by pedofauna.

In organic and organo-mineral fertilizers, the quality of the organic matrix depends strongly on its degree of humification, in particular on the content of humic and fulvic acids, typically present in stable humus. In addition to performing the beneficial actions on the soil structure described above, humic acids slowly incorporate and release nutrients, reduce the effects of salinity, neutralize the pH and have phytostimulant actions. Fulvic acids, with a lower molecular weight than humic, have an important chelating effect against some nutrients and can be absorbed by roots.

For almost 50 years Agribios has been producing organo-mineral fertilizers, taking care of the entire manufacturing process: from the careful selection of raw materials to their transformation, which takes place at the plants located in Villafranca Padovana (PD) and Canneto sull’Oglio (MN), right up to the packaging of the finished product and its distribution.

The organic matrix is represented in most cases by a mix of manure subjected to a long maturation process during which the manure ferments, humidifies and dries naturally. The line of organo-minerals specifically developed for organic farming also includes organic matrix products deriving exclusively from vegetables.

Agribios organo-mineral fertilizers have certain specific features, in terms of quality and their agronomic performance:

• the fermentation process, which lasts over six months, releases heat and raises the temperature of the mass to peak at 80°C, capable of generating a sort of “pasteurization” that eliminates pathogenic microorganisms dangerous to humans potentially present in starting manure (Salmonella, Escherichia, Nematodes). During fermentation, moreover, the pH of the mass is lowered from the initial values of 8 — 8.5 to the final 7. The neutral pH creates the conditions for maximum absorption of most of the nutrients contained;
• the organic matrices produced by Agribios contain organic carbon in much higher levels than the minimum (7.5%) required by current legislation. The long fermentation process also promotes the formation of humic and fulvic acids, with consequent greater nutritional efficiency of the fertilizers, in which the matrix will be used thanks to the reduction of washout, evaporation, retrogradation and fixation;
• drying takes place naturally, without the use of ovens, in indoor facilities; this promotes a complete and quick melting of the pellets (within a few minutes) once distributed to the ground.

Agribios offers a wide and complete range of organo-mineral fertilizers.

Two lines, one intended for organic production and one for conventional (or rather, integrated) production, united by the very high-quality standard of the organic matrices used, whether deriving from animals (Biocomplex line for organic farming, and the Agrical, Agriazoto, Agricomplex, Agriolivo Agriorto, Agrisprint, Agrivigne, Dorado, Ortofrutta, Superprimo lines for conventional farming) or vegetables (Vegastar line for organic farming).

The organic matrix guarantees the best conditions for making the nutrients contained in the product available to the plant, whether they are main ingredients, such as in NPK and NK fertilizers, or main ingredients associated with secondary ones (Calcium, Iron, Magnesium, Zinc, Sulfur).