Types of fertilizers

What are fertilizers?

It is called fertilizer to every one compound that contributes to the nutrition of the plants being added to the soil, which is the most common form of application or applied directly to the plant . In addition to water, air and light, vegetables need mineral nutrients to grow and develop, some in greater quantities, and others in lower proportions.

The former are known as macronutrients or macroelements and the main ones are nitrogen, phosphorus, potassium and sulfur. The second are the so-called micronutrients or microelements, iron, copper, molybdenum or zinc are part of this group.

When soils do not have adequate amounts of these minerals, or when its bioavailability to be taken efficiently by the plant roots is low, it decreases the growth and thus the yields of crops, sometimes deficiency Nutrients affect not so much plant growth, but rather the quality of the harvested product (for example, grain). In both cases, it is recommended to resort to fertilization.

Classification of fertilizers

Fertilizers can be classified on the basis of different criteria.

-A traditional criterion is one that takes into account the nutrient that you want to provide. Thus, we recognize the following examples:

• Nitrogen fertilizers: for example, urea, ammonia, ammonium nitrate
• Phosphorous fertilizers: simple superphosphate, triple superphosphate
• Sulfur fertilizers: gypsum (calcium sulfate)
• Potassium fertilizers: potassium chloride
• Combination fertilizers (provide more than one nutrient): nitrophosphates, NPK

-Another criterion is the one that refers to the place where the fertilizer will be applied :

• Edaphic fertilizers: they are incorporated into the soil in different ways (broadcast, in bands or rows, in cover, between lines), then the roots of the plants absorb them and distribute them to all organs
• Foliar fertilizers: they are applied on the leaves of the crops with the appropriate agricultural machinery to achieve a correct distribution (commonly with sprinkler equipment). Not all vegetables have an adequate epidermal cover to efficiently receive foliar fertilization.

-Another criterion considers the mode of presentation of the fertilizer or formulation . The following types are thus distinguished:

• Liquids
• Solid
• Granules, tablets (these are generally slower release)

-As some natural substances and can be a source of nutrients, it is also possible to distinguish between:

• Artificial (or synthetic) fertilizers : they are obtained through industrial processes , which generally increases their cost.
• Natural fertilizers: they are obtained directly from nature , such as dolomitic lime or phosphorous rock. Within natural fertilizers, an important subgroup is usually included, which is that of organic fertilizers or fertilizers, such as manure, guano or bone meal. These products provide nutrients after a slow microbial decomposition process. They have the advantage of being cheaper than the previous ones.
• Biological fertilizers: they correspond to a new generation of products for agriculture, considered more environmentally friendly. They are based on the action of beneficial microorganisms for plants that contribute to their nutrition in an indirect way, by solubilizing phosphorus or fixing atmospheric nitrogen.

The diagnosis of the need for fertilization of a crop is a complex task that demands the intervention of professionals or highly trained personnel, since it is based on the detection of symptoms of nutritional deficiency.

On occasions, the crops do not respond to fertilization because the soil pH does not allow the correct solubilization of the incorporated mineral; in this case, the practice of amendments tending to correct the pH of the soil solution is essential.