Plant fertilization is always a bit complex if it has never been done. There are many formulations and each crop requires a specific fertilizer or fertilizers to get it right. Moreover, at each phenological stage of the crop, the nutrient supply will be different.
Is there a best fertilizer for everything? The truth is no. The specificity of each crop, substrate and situation, requires different types of fertilizers that we will see later, but it is true that there are very specific ones in their formulations for different crops and uses.
But first, let’s take a look at plant nutrition in broad strokes in case you’re new to plant nutrition.
- The essential macronutrients for almost all plants.
- The best fertilizers are given in highly technical crops.
The essential macronutrients for almost all plants.
There are 3 of them and you will know them very well if you have already browsed this blog several times. The famous NPK. Nitrate, phosphorus and potassium.
And don’t you wonder why carbon is not included? After all, living things on this planet are based on carbon chemistry.
They get it mainly from CO2 which they metabolize with photosynthesis. This carbon is the building block of glucose and many other molecules that plants metabolize.
The 3 NPK macronutrients are not found in the air in sufficient quantities for a plant to supply. It is true that air contains about 79% nitrogen but it is considered inert because it is nitrogen gas N2. This molecule contains a triple bond which makes it extremely stable and it is difficult for it to react directly with the plant. Some plants can feed on atmospheric N2, with a few exceptions. The most common is that atmospheric nitrogen undergoes a cycle, in which it fixes itself in the soil, converting in the medium and long term into mineral nitrogen, the way in which plants must absorb it for their metabolic processes.
These three macronutrients can come from different origins, organic or mineral, which we will see later. Now we will focus on what is the function of each of them. It has many functions but the most notable are:
Nitrogen: Very important in the early stages of cultivation and in the growth of the vegetative part of the plant. Nitrogen is often said to be important for the “green parts” of the plant.
Match: Important for the establishment of the crop in its vegetative phase (stimulates root development). In addition, we must have a good phosphorus content to ensure good flowering and good fruit set.
Potassium: Important in fruit formation and ripening. It is a very important element in fruit trees, for example, to obtain large and quality fruits.
The proportions of each of them in a formulation depend on the crop, the moment in which the crop itself is (early phases, flowering, fruit set…) and the nutritional quality of the soil that we have to supply. Here are some examples of common formulations:
- NPK 13-40-13
- NPK 15-15-15
- NPK 15-5-30
- NPK 15-10-15
- NPK 17-6-18
- NPK 20-20-20
There are many, many more.
And if there is macro, it is because there are also micronutrients
Almost 99% of the minerals the plant needs are these three. And while micronutrients in quantity pale in comparison to NPK, their importance in small doses is vital to many metabolic functions in plants.
These are mainly iron, manganese, zinc, copper, boron and molybdenum.
Deficiency of any of these nutrients also causes serious damage to plant growth that is often mistaken for diseases caused by viruses, fungal bacteria or nematodes. Iron chlorosis is a typical example of iron deficiency.
Subscribers’ diets must also include certain very controlled doses of these micronutrients in their formulas. Normally good organic fertilization in the form of humus, compost, matured manure, green manures, etc. It generally provides these essential micronutrients and others that we have not mentioned.
The best fertilizers are given in highly technical crops.
It has already been shown that excessive fertilization is very detrimental to the environment. Poorly executed fertilization due to excess can negatively affect the plant, it can alter the balance of the soil, both at the physico-chemical and biological level. It can also contaminate groundwater, rendering the water completely unusable for human consumption.
Therefore, more and more the doses are optimized to the maximum and better and better fertilizers are produced, each time more specific and technical.
These crops with high investments such as greenhouses with or without soil (hydroponics), the dosage of macro and micronutrients is surprisingly accurate. The return on investment is also something that determines the choice of fertilizers and we can afford this level of technology. Greenhouse crops, for example (tomato, pepper, strawberry, etc.), are typically technical crops.
And if we go to hydroponics where liquid fertilization is making its presence known, then the levels of fertilization modernization skyrocket.
Fertilizers according to their formulation:
simple fertilizers: Those that supply a single nutrient to the plant. They are used less and less, in favor of complex fertilizers. In any case, for specific corrections or very particular needs, they are always used.
Compound Fertilizers: It contains two or three of the essential macronutrients. They are said to be binary (2 of the 3 nutrients) or ternary (the 3 nutrients) depending on their formulation. They can be complex (NPK having reacted chemically in the same granule) or be mixtures (granules of each nutrient separately and mixed).
Fertilizer according to their condition:
solid: They usually come in the form of granules. They are very common in large-scale monocultures (rainfed and irrigated) such as cereals, legumes, etc. From the fertilizer industry. They are synthesized in such a way as to ensure that each granule has the same composition and balance of each nutrient. This type is predominant in conventional agriculture.
liquids: These are the best fertilizers in high-tech crops where the fertilizer goes hand in hand with the irrigation water. In high-yielding crops such as marijuana, these very specific types of products are usually administered. And they are also completely organic fertilizers with their specific proportion of NPK and variable and balanced contents of the previously called micronutrients. Products such as Biological Activated Cocktail BAC fertilizers or Advanced Nutrients Fertilizers are an example of the wide variety of formulas, mixtures and application forms.
Fertilizers according to their mode of application
Another common classification occurs in the mode of application, although this classification is more open.
Funds disbursements: These are those that are applied to the soil before the establishment of the crop or at the time of sowing and are generally controlled release.
cover fertilizer: Fertilizer that is applied during a specific phase of the crop to nutritionally support a crucial phenological state for the crop, such as flowering or fruit set.
Fertilizer for foliar application: Those which are applied sprayed on the leaves as a support for fertilization
Fertilizer for fertigation: These are those that are mixed with irrigation water. Used in technical irrigated crops where the irrigation dose is controlled to the nearest millimeter (greenhouses, hydroponics).
None of these classifications are exclusive. In other words, the more information we have or can give about a fertilizer, the more certain we will be about using it. An example may be a liquid ternary compound fertilizer for foliar application 10-20-10. With that, we give a lot of what this fertilizer looks like.