Why use fertilizers?

For plants to thrive they need sunlight, water and also minerals. This scientific fact was discovered 200 years ago by the agricultural scientist Carl Sprengel. In 1828 he identified twelve substances as nutrients. These included potassium, magnesium, nitrogen and calcium, which plants draw from the soil through their roots. Sprengel is considered a pioneer of modern agricultural science.


A potato – when crops are harvested the nutrients stored in the plants are also removed from the field.

Sprengel’s research into how plants are nourished was pursued further by the German chemist Justus von Liebig. There was a pressing need for such work – following the industrial revolution, around the middle of the 19th century the crucial question was being asked of how the steadily growing population could be provided with sufficient food. The answer was by targeted nourishment of plants using fertilizers. Although soil contains natural reserves of nutrients in different combinations and concentrations, those reserves are not inexhaustible. Every growth cycle draws minerals from the soil, which are then carried away with harvested crops. To prevent the ground from being progressively depleted, leading to decreases in plant growth, the consumed minerals must be replaced by fertilizers.

Liebig’s discovery that plants need the nutrients nitrogen, phosphate and potassium for optimum growth led to the introduction of compound fertilizer. The practical application of Liebig’s ideas subsequently led to harvest yields being increased many times over. In fact between 1873 and 1913 agricultural production in Germany increased by 90%. This increase was based on the use of fertilizers obtained by both mining and industrial production. The first fertilizer factories, which primarily produced phosphate and superphosphate, appeared in Germany as early as the mid-19th century. However, it was not until the discovery of potassium bearing salts in Staßfurt in 1856 and the start up of the world’s first potash mine that this raw material became available large enough quantities to be used by farmers over extensive areas.

Until 1918, the German Empire was the only producer of potash. Today potassium is also mined in Canada, Russia, Belarus, the Dead Sea, etc.


Portrait of Justus von Liebig

Without the knowledge and application of the principles that Justus von Liebig formulated in the field of agricultural chemistry, it would not be possible to feed today’s urban industrial societies. He is therefore rightly considered the founder of the age of mineral fertilizers.

The blend is what counts

However, it is not enough to provide plants with individual nutrients in the right quantities and at the right point in their growth cycle. The nutrients must also be supplied in balanced proportions. Not only potassium, nitrogen and phosphate in the right proportions are required for plants to develop properly.

They also need various quantities of magnesium, sulphur or “micronutrients” such as calcium, iron, zinc, copper, boron or manganese, which can activate certain enzymes and thus control plants’ metabolism. If only one nutrient is missing, even providing all the others in the right quantities will do no good. This was pointed out by Justus of Liebig in his “Law of the Minimum”, published in 1840.


An old advertisement (archive)

The Law of the Minimum – every nutrient counts

The “Law of the Minimum” formulated by Justus of Liebig holds that the growth and yield of plants are limited by the factor which is in shortest supply. This can be a factor which is beyond man’s control, such as light or heat, but also one that can be controlled such as the nutrients in the soil. In fact any nutrient can limit growth and/or yield if it is not available in the optimum quantity for the plant.

But how can the farmer know what is lacking in his soil? Supplying minerals in arbitrary fashion will not automatically satisfy the specific requirements of the soil, and not all soil is equally suitable for the cultivation of different plants. For example, rich black earth involves entirely different requirements for a certain plant species than less fertile sandy or chalk soil, and every farmer knows that beet has an entirely different appetite for nutrients from barley or wheat.

Before fertilizers are used the soil must be analysed

The use of fertilizers must always be preceded by an assessment of the land. This involves carrying out analyses of the soil, which allow the farmer to precisely determine which nutrients are present in the soil in what proportions and concentrations.

On the basis of its research activities and field trials, K+S is able provide effective guidance on the use of fertilizers. Our expertise in this area enables us to carry out a targeted, location specific assessment of forms of nutrients, fertilizer quantities and the fertilising timeframe. K+S KALI GmbH is currently conducting approximately 130 field trials all over the world. The tests we conduct under constantly changing conditions provide further proof that potassium and magnesium increase the yield and quality of crops.


Consultation in the field

K+S’s specialists not only work on optimising potassium, magnesium and sulphur fertilizers, but also develop fertilisation recommendations and provide advice to farmers all over the world.

How do nutrients affect plants

Overview of the most important nutrients and minerals, the elixir of life for plants:

  • Nitrogen (N) is a building block of protein and all protein-type compounds in metabolism, as well as a component of chlorophyll. Because growth is controlled by nitrogen, it is considered to be the “motor” of plant growth.
  • Phosphate (P) is a component of numerous important compounds in plant organisms and therefore affects all plant metabolism. It significantly boosts the development of blossoms and fruit.
  • Potassium (K) regulates plants’ water regime, increases their physical stability and makes them resistant to frost, dryness, fungus infections and parasites.
  • Magnesium (Mg) is an important building block of the green plant pigment chlorophyll, which plays a key role in the use of sunlight to produce energy (photosynthesis).
  • Sulphur(S) is used in protein building and thereby ensures that nitrogen is utilised. It is essential in the process of building carbohydrates (starch and sugar), vitamins, enzymes and flavourings.

Premium mineral fertilizers – the elixir of life for plants

K+S KALI GmbH processes crude potassium and magnesium salts containing the life essential minerals potassium, magnesium and sulphur into premium mineral fertilizers for use in agriculture. It keeps stocks of suitable fertilizer products for a wide variety of soils and plants. Our modern potash mines in Germany have total production capacity of approximately 7.5 million tonnes of potassium and magnesium. Considerably more than half of that is exported to around 70 other countries. Besides potassium, the German deposits also contain magnesium and sulphur (the only deposits in the world to do so), which means that these important plant nutrients can be extracted simultaneously and processed into top quality mineral fertilizers. For example, our potassium sulphate contains little salt, in contrast to the more generally used potassium chloride. It is therefore particularly suitable for the targeted fertilisation of chloride sensitive crops and also counteracts soil salination.

Summary of fertilizer specialities

Soil fertilizerMain nutrientsCrops and applications
60er Kali® K All chloride tolerant crops, for example cereals, corn, soya and sugar beet; the potassium chloride component in compound fertilizers.
KALISOP® K, S All chloride sensitive crops; essential in tobacco, fruit and vegetable cultivation; the potassium sulphate component in compound fertilizers; permitted in organic farming.
Magnesia-Kainit® K, Mg, Na, S Primarily used for the cultivation of grassland and crops used as feed for livestock; sodium containing crude potassium salt; suitable for organic farming.
Korn-Kali® K, Mg, S Standard agricultural fertilizer, used for cereals, corn, sugar beet and rape in many European countries; used as a single-nutrient fertilizer as well as a component in blended fertilizers.
Patentkali® K, Mg, S For magnesium requiring, chloride sensitive crops, particularly potatoes, but also field vegetables, fruit and grape vines; suitable for organic farming.
ESTA® Kieserit Mg, S A fully water-soluble magnesium and sulphur fertilizer for agriculture, horticulture, forest crops and special crops, particularly for rape and oil palm; suitable for organic farming.


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