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Soil tests – why should we conduct them?

Knowing the composition of soil allows farmers to consciously choose proper fertilizers for their harvests. The analysis of the chemical elements gives a broader picture of real soil requirements for nutrients. The quality of harvests depends on the condition and fertility of soil, that is why a soil test allows to get to know its chemical composition. We can see the physical properties with the proverbial naked eye but the chemical ones unfortunately not. Fortunately, development of agriculture and technology allows us to obtain such knowledge through various devices.

soil sests NPK

Knowledge as a basis for action

Getting to know the ingredients that soil should have is the first step to conscious agriculture. Specific crops require specific ingredients. Their deficiency or excess can have a negative consequence. Knowing that soil is a non-renewable component, caring about its condition is a key element of agriculture. There is, of course, a possibility of its regeneration but the time of such process is very long, so soil should not be regarded as a renewable resource.


What are different elements in soil responsible for?


Phosphorus in soil

This element is primarily responsible for proper development of a root system. It improves the rooting of plants. It develops the biological activity of soil, as it allows to use the other components much better. It also has a positive effect on plants resistance to frost, water deficiency and diseases. Phosphorus helps to reduce the accumulation of the harmful forms of nitrogen in plants. It is responsible for proper development of seeds and grains. Phosphorus overfertilization does not occur in principle because plants do not take up the excessive quantities of it (which can be observed in case of nitrogen and potassium).

Phosphorus intake depends on soil temperature and reaction. Plants absorb it through the root-hairs zone.

Phosphorus deficiency is manifested by the slow plant growth, purple-violet colouring of leaves and stems, rotting of leaves ends as well as poor flowering of flowers.


Potassium in soil

It is mainly responsible for water management of cultivated plants. It is one of the most important plant nutrients. It determines the quality of crops and its largest quantities can be found in heavy soils. Plants containing a proper amount of potassium are very resistant to drought and have more starch, protein, sugar and pectin in themselves. Potassium activates more than 50 enzymes and participates directly in the nitrogen metabolism in plants.

Potassium deficiency inhibits the growth of plants, causes them to wilt and worsens the taste of vegetables.

Tomatoes, peppers, rapes, onions and potatoes are particularly sensitive to the deficiency of this element. Excessive fertilisation can make fruit too sour and more difficult to store.

The soil tests on abundance of this element are particularly important, as it significantly affects the magnesium content in plants. Its overfertilisation may result in blocking the absorption of this component.


Nitrogen in soil

Plants need nitrogen because it is the building material of proteins and nucleic acids. It is also a component of vitamins, alkaloids, nucleotides and chlorophyll. The various sources of its origin can be mentioned, e.g. precipitation, mineral and organic fertilizers or plant and animal residues. The nitrogen content in soil is very much related to humus. More nitrogen is found in fine-grained soils, with the highest nitrogen content in chernozems or rendzinas. Nitrogen in soil occurs in an inorganic and organic form.

Nitrogen deficiency influences a slowdown of the plant growth and causes yellowing of leaves and premature lignification of stem tissues.

Knowing the mineral nitrogen content of soil is very crucial. The analysis of a soil sample in early spring will help to select a proper fertiliser but a post-harvest test will enable the farmers to assess the effects of the used nitrogen fertilisation. The fertilisation periods should also be considered while nitrogen fertilisation!

NPK soil tests

Soil tests in the laboratory

The University of Agriculture has had a modern soil testing laboratory since 2018. The technology based on spectroscopy which is used there allows to test as many as 21 soil parameters.

Lab-in-a-box is a modern technology which is an alternative to wet chemistry and in a very short time allows to obtain the results of the analysed sample.

The cost of such a test is 95 PLN. Every farmer can now carry out such soil test by sending the samples by courier to the University of Krakow.


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