Agricultural fertilizers: do you know all the options?

Searching for the right fertilizer for our crop can be crazy if we don’t have the slightest idea of ​​its composition and classification.

Although nitrogen is commonly associated with germination, phosphorus with flowering and root formation, and potassium with ripening, the world of fertilizers is much more complex than one might think.

In this article we want to make a classification of agricultural fertilizers that can be found on the market, as well as the concentrations and doses usually recommended.


Types of Fertilizers You Can Find

The classification of a fertilizer can be done in several ways. It can be solid (mixture, complex, granules), liquid or in the form of a suspension or gel, as we have recently found on the market.

But it does not stop there, since it can also be classified by its composition, by its origin, by its main use, etc. We will make a brief review of each of the options available to us for agricultural fertilizers in order to clarify ideas.

By its origin: organic or inorganic

Organic fertilizers

A fertilizer or manure, as it is traditionally called, is first classified by its Origin. It can be inorganic or organic. There is nothing left. The separation of concepts is done as follows:

  • Inorganic fertilizer: mineral origin of the mine or saltpeter, either naturally or with physico-chemical transformation processes.
  • Organic fertilizer: fertilizer from the transformation of plant or animal remains, whether manure or compost, from the fermentation of plant remains, amino acids, carbon-rich humic extracts, etc.

At this point, don’t confuse inorganic with artificial. Nothing is more natural than obtaining Potassium Chloride from the Dead Sea through a process as simple as filtration. However, its origin is inorganic, since large amounts of organic components, such as carbon, are not found.

Organic fertilizers are generally much more environmentally friendly, as they do not provide excessive conductivity (salts), they present no handling or storage hazards, and they generally promote the natural development of natural soil microbiology.

On the contrary, most of them are generally less active and available to the plantrequiring a transformation process (usually with the activity of bacteria in the soil) to increase its availability and uptake by the plant, such as organic nitrogen.

By its physical state: solids, liquids or gels

A simple but necessary classification consists in distinguishing a liquid fertilizer of one solid fertilizer. The latter is generally much more concentrated than the former, but requires prior solubilization before application.

If we buy it liquid, the factories generally tend to concentrate the fertilizer beyond our means, so if we value the reduction of our labor and our handling, this alternative is more efficient. On the contrary, if we have no storage problems and want to prepare our formula ourselves, the solid fertilizers they are the best alternative.

Currently, there are novelties on the market such as the pendant lightswhich are again ultra-concentrated liquid solutions where the water is replaced by surfactants and flocculants which keep the solid in suspension.

On the other hand also there are gel-based solutionsin a more solid state than suspensions (higher concentration), where surfactants and components are also used that maintain a dense gel state, as if it were a jam, but perfectly soluble in the water-

Solid fertilizer for eggplant

According to the legislation

If we classify fertilizers according to legislation, for example European (EC 2003/2003 and 2019/1009), the distinction is made according to the different families and components concerned.

This classification would be as follows:

  • Simple inorganic fertilizers with primary nutrients
    • Nitrogen fertilizers: in its composition there is only nitrogen.
    • Phosphate fertilizers: in its composition there is only phosphorus.
    • Potassium fertilizers: in its composition there is only potassium.
  • Compound inorganic fertilizers with primary nutrients
    • NPK fertilizer: mixture of nitrogen, phosphorus and potassium
    • NP fertilizer: mixture of nitrogen and phosphorus.
    • NK fertilizer: mixture of nitrogen and potassium.
    • PK fertilizer: mixture of phosphorus and potassium.
  • Inorganic fertilizers with secondary nutrients
    • Mixtures with magnesium, calcium and other components other than NPK
  • Inorganic fertilizers containing micronutrients
    • Individual micronutrients
    • Micronutrient Blends

On the other hand, each country has its own legislation. In the case of Spanish, agricultural fertilizers of organic or organic origin are included, as well as special fertilizers, considered as such because they contain amino acids, humic extract, algae and, currently, a type specific to microorganism.

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