Organic farming in the EU – in pursuit of the objectives of contributing to a high level of biodiversity and maintaining soil fertility in the long term (1) – allows the use of a limited variety of fertiliser products.
Below is a brief review of the available inputs, between tradition and innovation.
1) Nitrogen
Organic nitrogen fertilizers are the only form allowed to provide nitrogen in organic farming. Research has therefore focused on treatments suitable for optimizing the availability of natural protein sources, of vegetal and animal nature, to plants.
Plant derivatives most important are:
-borlanda, a residue from sugar production;
-pellets, a residue from oil seed processing and fruit juice production;
-algae extracts.
Numerous organic nitrogen fertilizers also come from the animal kingdom it, such as:
-manure, the use of which requires adequate maturation;
-slurry, which should not be applied in direct contact with the roots as it is not mature;
-guano and poultry droppings, that is, bird droppings,
-blood derivatives, mainly bovine and porcine;
-various other products and by-products of animal origin. (2)
2) Phosphorus
Phosphorus nutrition in organic farming is a great challenge. The only permitted mineral forms have a very low availability, especially in calcareous soils:
-most soils in Italy, Spain, Greece and a good part of those in France have a very high limestone content, a significant quantity of calcium and a pH often around 8;
-all of the above conditions lock up phosphorus in most mineral forms, preventing the roots from absorbing it. (3)
Some organic fertilizers which naturally contain phosphorus – such as chicken manure, guano and wood ash – are among the most suitable for providing phosphorus in organic farming.
3) Potassium
Once again, the few mineral forms permitted as fertilizers in organic farming are found in their raw state and are poorly available to the plant, especially in clay soils.
The borlands are probably the organic forms that contain and make available the most potassium, although its quantity is around a few percentage points.
4) Carbon
In organic farming the organic form of fertilization with the three macroelements nitrogen (N), phosphorus (P) and potassium (K) is therefore preffered. However, sometimes neglecting the main element in any organic fertilizer, carbon (C).
Carbon– a basic element of life on earth – is as necessary as water to plants, which absorb it from the atmosphere through photosynthesis to create complex organic substances (sugar).
However plants do not only need the sugar produced in the leaves, from which they draw so much energy, but also the many forms of organic carbon. Which are found naturally in forest soils, and should be added to cultivated soils.
4.1) Humic acids
The main organic substances found in the soil are humic acids. These are the final product of the degradation of all biological material foreign to the soil (i.e. fallen leaves and branches, animal droppings and carcasses).
A multitude of organisms participates in the natural creation of humic acids. Earthworms and other small animals that live in the soil, as well as the extraordinary complex of soil microorganisms (i.e. bacteria, fungi, algae, actinomycetes, etc.).
Each of these organisms plays a specific role in the degradation of foreign organic substances and the resulting product is called humic acid. (4)
4.2) Leonardite
The Leonardite– a form predating the formation of charcoal fossil, formed in about 200 million years– is the basis from which most of the humic acids that can be used in organic farming are extracted.
This fossil has a high concentration of substances very similar to humic acids found in nature. However, some of the substances contained in leonardite can be toxic to plant roots.
5) Biostimulants
Fertilizing Products Regulation (EU) No 2019/1009, as we have seen, has extended the regulation of fertilizers to recycled and organic materials, including organic, organo-mineral fertilizers and biostimulants, most of which are also permitted in organic farming (5,6).
5.1) Functions
Plants biostimulants aim to stimulate the physiological processes of plants, regardless of nutrient content, with the sole purpose of improving one or more of the following characteristics of the plant or its rhizosphere:
-efficiency of use of one or more nutrients;
-tolerance to abiotic stress;
-qualitative characteristics;
-availability of nutrients contained in the soil or rhizosphere. (7)
The category of biostimulants is thus divided by function rather than by formula, and is registering a growing success which however deserves attention, on a case-by-case basis, to seize the opportunities without disappointing expectations.
5.1) Evidence of efficacy
The operator whishing to communicated the functions and properties of a biostimulant – as well as of a biopreparation based on microorganisms (8) – must conduct a number of field or greenhouse trials on specific crops in accordance with the Fertilising Products Regulation.
The regulatory trials are, however, approximate, from an agronomic point of view, compared to the extraordinary biodiversity of crops and soils
The best proof of the efficacy of a new product is therefore that everyone can carry out on a portion of their own land, in comparison with another portion not subjected to identical treatment.
Jacob Govi
Footnotes
(1) Donato Ferrucci, Dario Dongo. Production and labeling of organic products, EU regulation 2018/848 is underway. The ABC. GIFT (Great Italian Food Trade). 2.2.22
(2) Commission Implementing Regulation (EU) 2021/1165 authorizing certain products and substances for use in organic production and establishing their lists. Latest consolidated version 15.11.23 https://t.ly/9Xtsv
(3) P. Sequi, Soil Chemistry (Patron editore, Bologna, 1989). ISBN/EAN: 9788855520690
(4) N. Rossi, C. Ciavatta, P. Sequi. Contribution of agricultural land in the Po Valley to coastal eutrophication of the Adriatic Sea. Editor(s): RA Vollenweider, R. Marchetti, R. Viviani, Marine Coastal Eutrophication. Elsevier, 1992, Pages 349-364. ISBN 9780444899903. https://doi.org/10.1016/B978-0-444-89990-3.50031-6
(5) Dario Dongo. Fertilizers and circular economy, the new EU rules. GIFT (Great Italian Food Trade). 18.11.19
(6) Regulation (EU) 2019/1009 laying down rules on the making available on the market of EU fertilizing products and amending Regulations (EC) No 1069/2009 and (EC) No 1107/2009 and repealing Regulation (EC) No 2003 /2003. Latest consolidated version 3.7.24 https://t.ly/7ru7A
(7) Reg. (EC) No 1107/2009, new point 34 in Article 3
(8) Gabriele Sapienza. Biopreparations based on microorganisms, regulation and benefits. GIFT (Great Italian Food Trade). 4.10.23
