- What are NPK fertilizers?
- What NPK fertilizers are there?
- What are the pros and cons of NPK fertilizers?
- Application of NPK fertilizers
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When gardening, you cannot avoid the term NPK fertilizer. We explain what NPK means, what the advantages are and give examples of use.
NPK fertilizer sounds like a rather cryptic term that you probably don't immediately know what it means. What do N, P and K stand for? The answer to this question is just a paragraph away from you. Immediately afterwards we present some common NPK fertilizers. You can read about the advantages and, above all, disadvantages of NPK fertilizers after we have explained the differences between organic, mineral and organo-mineral NPK fertilizers. At the end of this article you will also find a section on applying the appropriate NPK fertilizer to lawns, roses and fruit trees.
What are NPK fertilizers?
First the three letters: they stand for the chemical elements that make up the NPK fertilizer. The N stands for nitrogen, the P for phosphorus and the K for potassium. These three elements are what are known as macronutrient elements. Plants generally require these in large quantities for growth and survival. An NPK fertilizer is a fertilizer that contains at least these three nutrient elements. In some preparations, additional nutritional elements are added. Ca (calcium), magnesium (Mg) and sulfur (S), for example, are often added because they are also considered macronutrients.
The following is information about the functions that N, P and K have for the plant:
Nitrogen (N)
Plants use most of the nitrogen to build proteins, DNA and chlorophyll. Chlorophyll is the green plant pigment that is essential for photosynthesis to take place. Proteins and DNA are of course also indispensable. It is not without reason that nitrogen is referred to as the “motor of vegetative growth”.
Phosphorus (P)
Phosphorus is also required in proteins (specifically in enzymes). It's also in the structure of DNSinvolved. It is also one of the main components of ATP (adenosine triphosphate), which is the energy currency of all cells. This probably makes it clear quickly that no plant can live without phosphate. In addition, phosphorus stimulates flowering and fruit formation, which is of course particularly relevant for hobby gardeners.
Potassium (K)
Potassium - unlike nitrogen and phosphorus - is not used directly in the construction of new cell structures. Instead, the plant stores potassium in its vacuole, in the (usually) central, water-filled space of each cell. A high concentration of potassium in the vacuole means that the cell can absorb and hold water much better. In this way, potassium serves to regulate the water balance of the entire plant. In addition, liquids with a high concentration of solutes have a much lower freezing point. With a high concentration of potassium in the vacuole, the plant is better prepared for severe frosts.
But that's not all: Potassium supports the activity of many enzymes and thus also influences the plant's metabolism. A good example is the aid in the formation of cell walls, as a result of which the plant is more stable and resistant to fungal attack and sucking insects.
But back to the NPK fertilizers: If you turn the packaging of a fertilizer over, you will always find the same information in a (usually) square box: Separated by dashes, there are a number of numbers in a row (unless you hold a straight fertilizer - i.e. a fertilizer that contains only one nutrient - in your hand). With our Plantura organic universal fertilizer, for example, you will find the information "6 - 3 - 4". These three numbers indicate what percentage of the nutrients are contained in the respective fertilizer. Sometimes there are more than three numbers in a row. However, the order in which the nutritional elements are given is always the same: N - P - K (+ Mg ,+ S) , where Mg and S stand for magnesium and sulfur, two very important macronutrient elements. Our Plantura organic universal fertilizer contains 6% nitrogen compounds, 3% phosphorus compounds and 4% potassium compounds. We deliberately call it "nutrient compounds" here, because the plant nutrient in the fertilizer is of course not in the element form, but in a different chemical compound.
Summary of the meaning of NPK fertilizer:
- The letters N, P and K standfor nitrogen, phosphorus and potassium, the three main nutrients of plants
- The labeling of fertilizers always follows the general form: N - P - K
- After N - P - K, other elements such as Mg (magnesium) and S (sulphur) are named
- Nutritional elements are present as chemical compounds, the percentage of which in the fertilizer is expressed as a whole number
- N is the "motor of vegetative growth"
- P promotes flowering and fruit formation
- K regulates the water balance, strengthens frost resistance, ensures firm plant tissue and increases resistance to fungi and sucking insects
What NPK fertilizers are there?
Within the NPK fertilizers, a distinction can be made between mineral, organic and organo-mineral fertilizers. Below we briefly describe the respective types.
Mineral fertilisers: The plant nutrient is present in these fertilizers in its pure, mineral form as "nutrient s alt". Many mineral fertilizers are coated so that the crystalline structure is no longer visible. The raw materials are mined from fossil deposits. So they do not go back directly to an organic origin. Mineral nitrogen is produced from elementary atmospheric nitrogen using the energy-intensive “Haber-Bosch process”.
Organic Fertilizers: The plant nutrient is present as part of an organic compound. It has to be released from the organic structures by the plant or the soil before it can be taken up by the roots. Many chemical reactions in the soil and especially in the root area are involved in this process. It takes a little longer before the nutrients are available to the plants. Humus can be formed from the organic material contained.
Organic-mineral fertilizers: Both mineral and organic components are used in these fertilizers. Sometimes also different compounds for a single nutrient element. The purpose of this is to exploit the different operating speeds and properties of the compounds.
In addition, these fertilizers are available in liquid and solid form. Liquid fertilizers contain the nutrients in dissolved form and are therefore immediately available. They should therefore be used in small doses but more frequently (about every two weeks). Some solid fertilizers can be dissolved in water, making them available more quickly. themost NPK fertilizers for hobby gardening are available in the form of granules that can be spread.
Examples of Solid NPK Fertilizer Types
In the following we present three NPK fertilizers of the different categories.
Blaukorn by Compo-Expert: 12 - 8 - 16 (+3)
Blue grain is probably the most famous mineral fertilizer. As you now know, it contains 12% nitrogen compounds, 8% phosphorus compounds and 16% potassium compounds. There are also 3% magnesium compounds.
Blueseed is avoided by many environmentally conscious gardeners for understandable reasons. Problems with its use are, for example, that this fertilization reduces soil life without organic input. Mineral nitrogen penetrates into deeper soil layers all too easily and the groundwater can be washed away. Apart from that, over-fertilization is possible if the dosage is incorrect. This can not only lead to unnatural growth (the so-called "growth"), but also increase susceptibility to frost. And even the immediate death of the plant can be the result of too high a dosage. Price: 25 kg costs about 30 euros.
Manna Tree Fertilizer: 6 - 8 - 10
Manna's tree fertilizer is particularly suitable for fertilizing trees and shrubs. Due to the great stability of trees and winter hardiness, the potassium content is relatively high. Due to its combined composition, the fertilizer should ensure both immediate and long-term fertilization over several months. Depending on the activity of the soil, the nutrients only become available when the plant actually needs them. The proportion of organic material should also revitalize the soil and stabilize the humus content. Price: 25 kg costs about 50 euros.
Organic universal fertilizer from Plantura: 6 - 4 - 4 (+0, +2)
Our Plantura organic universal fertilizer is also an NPK fertilizer. As you can see, in addition to N, P and K, there are also sulfur compounds.
As a primarily organic fertilizer with a long-term effect, it has the full potential to make the soil better and more efficient in the long term. The plus in sulfur ensures that many important metabolic processes in the plant run smoothly. Another distinctive feature is that the raw materials for this fertilizerare completely animal free. Many other organic fertilizers use shredded livestock residues such as bone or horn. Unfortunately, these often produce a rather unpleasant smell, which of course does not occur with this fertilizer. This means it can also be used to fertilize indoor plants.
What are the pros and cons of NPK fertilizers?
Organic fertilizers and mineral-organic fertilizers are seldom truly pure NPK fertilizers, as the organic components also contain small amounts of other nutrients. The following comments therefore only refer to the really pure, mineral NPK fertilizers.
Mineral NPK fertilizers:
- NPK fertilizers contain the three main plant nutrients
- The price is usually lower compared to organic or combined fertilizers
- The nutrient content is often the highest; there is an immediate effect
Tip: Mineral nitrogen in the form of ammonium makes the soil slightly more acidic. Mineral nitrogen in the form of nitrate, on the other hand, makes it somewhat more alkaline. Keep this in mind when fertilizing plants that are sensitive to soil pH, such as avocados and rhododendrons. However, many fertilizers contain nitrogen in the form of ammonium nitrate, so pH is unaffected.
Disadvantages of mineral NPK fertilizers:
- Missing eleven essential nutrients plants need to grow
- If only mineral NPK fertilizers are used, the soil's supply of these other nutrients will be exhausted over time and deficiency symptoms will occur
- Mineral phosphorus is a scarce resource; if possible, less should be mined in order to be able to use the global reserves longer
- Manufacturing artificial mineral nitrogen using the "Haber-Bosch process" is very energy-intensive
- Due to the immediate effect, incorrect dosage can damage the plant
- Mineral nitrogen can be leached into groundwater by heavy rainfall, where it increases nitrate levels
- In the absence of stable organic matter, high levels of nitrogen can lead to humus degradation, resulting in a permanent deterioration in soil quality
So you see: At first glance, mineral NPK fertilizers bring immediate success - due to their high dosage, the green sprout andknows no stopping. Occasional use of these fertilizers alone is certainly not a problem. However, remember that your plants need much more than nitrogen, phosphorus and potassium. Therefore, supply your garden or your potted plants regularly with the other macronutrients magnesium, sulfur and calcium and trace elements by alternating between different fertilizers.
The introduction of organic material is also indispensable for maintaining soil fertility and should be taken just as seriously as fertilization. Organic fertilizers come in handy here because they combine both goals.
Application of NPK fertilizers
Many of you are probably wondering how NPK fertilizers can be used to fertilize lawns, roses and fruit trees. Here are some suggested uses.
NPK Lawn Fertilizer
There's one thing that many people don't know that makes them angry about their thin, mossy lawn: The flat green is surprisingly hungry and needs a lot of nutrients. Depending on the season, you should choose different fertilizers to have a lush green and he althy lawn in the garden.
Fertilize your lawn in spring
As soon as the 15 degree mark is exceeded, your lawn wants to grow. There is a lot of plant mass to build up, so you can start with a nitrogen-rich fertilizer. Divide up the amount you need and prefer to fertilize once in spring and then a little more in early summer. This reduces the likelihood of nitrogen leaching and allows your lawn to grow evenly.
Fertilize your lawn in summer
If it gets very hot and dry, your lawn will not be able to grow much. So water your lawn regularly. Too infrequent, heavy watering can wash out nutrients and lead to a lack of oxygen at the lawn roots. If possible, only apply nitrogen in a primarily organic form. If the summer is rather humid and warm, you can also carry out summer lawn fertilization with a balanced NPK fertilizer, such as our Plantura organic lawn fertilizer. However, increased nitrogen levels are no longer necessary. Pure mineral fertilizers should - if at all - only be used in small quantities.
Fertilize the lawn in autumn
Use an organic NPK fertilizer with a long-term effect. The potassium content should again be high, so that severe frosts are well tolerated. Organic FertilizersRelease needed nutrients only when needed, so your lawn can get the most out of each beautiful warm fall day without leaching or causing damage to nutrients. Our tip: The Plantura organic autumn lawn fertilizer.
Summary of NPK Lawn Fertilizer:
- The lawn needs a lot of nutrients
- Fertilize with nitrogen in spring and early summer
- Fertilize balanced in wet summers and high in potassium in dry summers
- Fertilize in autumn with little nitrogen and more potassium
NPK fertilizer for roses
Roses are floriferous shrubs that lovers can rave about. Only with a good supply of nutrients does this desire not become frustration. The queen of the plant world loves a balanced supply of nutrients. Therefore, make sure that the fertilizer does not contain too much nitrogen, as this reduces flowering and promotes shoot growth. In autumn you should rather use a potassium-rich fertilizer to avoid frost damage to your roses. During the summer, roses that bloom several times in particular need a lot of energy. It is therefore advisable to incorporate a good dose of mainly organic NPK fertilizer in the spring.
Summary of NPK Rose Fertilizer:
- Roses need a good supply of nutrients for their rich flowering
- Fertilizers that are too high in nitrogen make roses lazy and susceptible to pests
- Potassium-rich fertilization in autumn protects against frost damage
NPK fertilizer for fruit trees
Fruit trees use significantly less nutrients than you might think. Unlike vegetables, they only have to regenerate their leaves and fruit each spring and not a complete plant body. If the leaves and surplus fruit are simply left lying around or composted and applied again, the nutrient requirement is even lower. Of course, this option is only an option if the tree does not suffer from pests or diseases that survive through fallen fruit or leaves. One organic NPK fertilization per year is sufficient for fruit trees. However, this should be high in potassium to avoid frost damage. Carry out fertilization in autumn.
Summary of NPK Fruit Tree Fertilizer:
- Fruit trees have lower nutrient requirements than their size suggests
- Fertilize primarily organically and high in potassium
Not all plants need itthe same nutrient supply. Therefore there are also fertilizers with other compositions - for example PK fertilizers. In our special article we explain the advantages and disadvantages, as well as the effect and application of the fertilizer.