The more efficient plant varieties, the more precisely they should be mobilized to grow faster, but also the quality of the crop should be influenced. This goal can be achieved by thoroughly understanding the nutritional requirements and fertilization needs of plants, while observing basic laws. Get to know the most important ones and learn more about mineral fertilizers.
Mineral fertilizers – basic principles of fertilization
The most important of them is the von Liebig’s law, which informs that “the size of plant yield depends on the nutrient present in the soil in the smallest amount”.
The second important law is the principle of returning nutrients removed from the soil along with plant crops.
To sum up, the ecological and economic justification of fertilization is the adherence to the principle of “as much as necessary, as little as possible” – this also applies to strengthening the soil with nutrients through mineral fertilizers. In order to fertilize in this way, it is necessary to know the abundance of available nutrients in the soil, so perform soil analysis every 4-5 years. Only then are we able to consciously and accurately select the doses of minerals in fertilizers.
History of mineral fertilizers
Mineral fertilizers – colloquially known as artificial fertilizers – are substances used in plant cultivation to enrich the soil with nutrients.
The first experiments with artificial fertilizers were carried out around 1660 by the German chemist and doctor Johann R. Glauber. He used sodium sulfate, i.e. Glauber’s salt.
Phosphorus fertilizers
Mineral fertilizers have been introduced into common use in agriculture mainly thanks to the German chemist Justus Liebig. As a phosphorus fertilizer, Liebig proposed calcium phosphate, obtained by treating ground bones with sulfuric acid.
Potassium fertilizers and nitrogen fertilizers
As early as 1842, the Englishman John B. Lawes patented an industrial method of obtaining phosphorus fertilizer, called superphosphate. Another artificial fertilizer was potassium nitrate, obtained from the then discovered rich deposits, the so-called Chilean saltpetre. With a view to becoming independent from these supplies, at the beginning of the 20th century, the search for technical methods of obtaining nitric acid using atmospheric nitrogen began. In 1905, the first nitrate plant was built in Italy.
The first synthetic nitrogen fertilizer was ammonium sulphate, obtained from 1890 in Germany as a by-product in coking plants. Also in Germany in 1905 the production of calcium cyanamide (CaCN2), known as nitride, began. In 1902 in Norway, Birkeland and Eyde, and in 1903 in Poland, Mościcki developed a method for the synthesis of nitrogen oxide and nitric acid by oxidizing nitrogen from the air in an electric arc.
The basis of the current production of nitrogen fertilizers is the synthesis of ammonia developed in Germany in 1913 by Haber and Bosch. The authors of this achievement were honored with Nobel prizes: Haber in 1918 and Bosch in 1935. In 1921, a method for the synthesis of urea from ammonia was also developed in Germany.
As can be seen from this short review, the history of modern agricultural chemistry is almost 170 years old, and its greatest achievements affecting mineral fertilizers date back to the turn of the 19th and 20th centuries.
Division of mineral fertilizers
Mineral fertilizers are divided into:
- nitrogen fertilizers
- phosphorus fertilizers
- potassium fertilizers
- calcium fertilizers
- magnesium fertilizers
- multi-component fertilizers
Effectiveness of using mineral fertilizers
Basic agrotechnical treatments increasing the effectiveness of mineral fertilization are:
- correct agrotechnics, including soil cultivation, correct rotation – succession of plants, timely sowing and correct plant density as well as combating weeds, diseases and pests;
- proper selection of varieties – intensive varieties that respond well with high yields to fertilization;
- the correct level of fertilization, timely and even fertilization, and the use of good and relatively cheap fertilizers.
Efficiency of nitrogen fertilization
Basic agrotechnical treatments increasing the effectiveness of mineral fertilization are:
- correct agrotechnics, including soil cultivation, correct rotation – succession of plants, timely sowing and correct plant density as well as combating weeds, diseases and pests;
- proper selection of varieties – intensive varieties that respond well with high yields to fertilization;
- the correct level of fertilization, timely and even fertilization, and the use of good and relatively cheap fertilizers.
Efficiency of nitrogen fertilization
- Of all the nutrients, nitrogen fertilization increases the mass of the crop the most, but can also reduce its quality the most.
- The content of humus determines the possibility of accumulating most nutrients in the soil, including nitrogen, which means that it determines the amount of reserves and reduces nitrogen losses.
- It is important that the plants are well supplied with sulfur. Sulfur as a building element of protein (similar to nitrogen) improves the quality of the crop, including increasing the protein content. The higher the nitrogen doses are used, the more sulfur is absorbed by plants and the more often sulfur deficiency may limit the yield of plants, more and more often also cereals.
- Nitrogen should be used at optimum times. It is very mobile in the soil and is subject to losses, therefore divided doses of nitrogen should always be used in periods when it is possible to quickly absorb it by the plant.
- It is important to choose the right form of nitrogen.
- The ammonium form (NH4 +) is well retained (sorbed) in the soil. It is absorbed more slowly and evenly by plants, it also works well at low temperatures.
- The nitrate form of NO3 is not retained in the soil, therefore it is easily washed out. It works better at higher temperatures and there is no need to mix it with the soil, which is why it is a typical top dressing form, recommended for use in those phases of vegetation when plants grow intensively.
- The amide form (C-NH2) present in urea can be absorbed directly by plants, and relatively slowly through the root system. It is absorbed mainly after the enzymatic decomposition process in soil, first to the ammonium form and then also to the nitrate form. So it is a slow-acting form, recommended for spring (cover) fertilization of plants.
Effectiveness of phosphorus fertilization
Irregular phosphorus fertilization accelerates the processes of its regression in the soil, which means that it worsens its digestibility and limits the possibilities of effective supplementation of deficiencies.
Division of phosphorus fertilizers:
- AMOPHOS Group (NH4 – NP) – AMOPHOSIS (NH4 – NPK ….): nitrogen is in the ammonium form (NH4), phosphorus in the form of ammonium phosphate [(NH4) 2HPO4 and NH4H2PO4.
- NITROPHOS group (NO3 – NP) – NITROPHOSIS (NO3 – NPK ….): nitrogen is in the form of nitrate and ammonium (NO3 and NH4), phosphorus is in the form of calcium phosphate (CaHPO4) and ammonium phosphate [(NH4) 2HPO4 and NH4H2PO4].
The pH of the soil affects the absorption of phosphorus, especially when it is inappropriate for a given soil category. In very acidic soils, at the pH (in 1M KCl) below 4.5 – 5.0, the absorption of phosphorus decreases, which turns into practically insoluble compounds with aluminum, which is toxic to plants. Then the phosphorus shows no effect. The soil with a pH of 5.0 – 6.8 (in 1M KCl) contains the most monovalent H2PO4– ions, the most rapidly absorbed by plant roots. In neutral or alkaline or over-limed soils, the uptake of the bivalent HPO4 ion is much less (about 10 times) at a pH above 6.8. In practice, the effects of phosphorus over-fertilization are not observed, because plants do not tend to take up excessive amounts of phosphorus, as they do in the case of nitrogen and potassium.
Potassium fertilization effectivenes
For over 20 years, potassium has been the most deficient basic nutrient in Polish agriculture.
However, excess potassium is inadvisable, and even harmful – both for the soil and the plant. Too high doses of potassium cause its excessive accumulation in plants – mainly in green parts and roots (everywhere except seeds) – and being in excess, it worsens the biological, technological and storage value of the crop. Therefore, potassium mineral fertilizers (and not only) must be applied taking into account the soil’s nutrient requirements.
Effectiveness of calcium fertilization
Calcium is an essential macronutrient for plants. Calcium compounds are used primarily for liming, i.e. regulating the pH of the soil, and not fertilizing plants. In the soil, within the reach of plant roots, there is from dozen to several dozen tons of CaO/ha.
Magnesium fertilization efficiency
Magnesium is a very “mobile” element, so it is easily leached into the deeper layers of the soil profile. That is why it should be used regularly. As a rule, the lighter and more acidic the soil, the faster the magnesium is washed out.
Effectiveness of sulfur fertilization
The cultivation of sulfur-loving plants, i.e. rapeseed, mustard and other cruciferous plants (including cruciferous vegetables) requires greater attention to the problem of sulfur deficiency and its proper fertilization. In turn, the plowed in rapeseed straw, rich in sulfur, will protect the succeeding plant with this ingredient.
If you have questions about mineral fertilizers that are not answered in this article, please contact us! We are happy to answer your questions and advise which mineral fertilizers will work for your crops.
