Mineral fertilizers
In mineral fertilizers (also called inorganic fertilizers ), the fertilizing substances are usually in the form of salts . Liquid ammonia fertilizers are an exception. Mineral fertilizers have made great productivity gains in agriculture possible and are now widely used. Mineral fertilizers come either from mining (e.g. potash salts and lime ) or from chemical production processes (e.g. Haber-Bosch process ). Mineral fertilizers are used in granular, powder or liquid form ( liquid fertilizer ).
The synthetic nitrogen fertilizers are problematic in view of the large amount of energy required for chemical production. In contrast, organic fertilizers with appropriate cultivation methods lead to a higher humus content and a higher soil quality.
The first insights into the practical application of agrochemistry go back to Carl Sprengel about 200 years ago. Around 1840 the chemist Justus von Liebig was able to demonstrate the growth-promoting effects of nitrogen , phosphates and potassium . For example, nitrogen was initially obtained in the form of nitrates primarily through the use of guano , a substance that is formed from the excrement of sea birds. Since the natural reserves of mineral fertilizers are limited and most of them have to be imported from South America, a method of producing nitrogen compounds synthetically was considered . Between 1905 and 1908, the chemist Fritz Haber developed the catalytic synthesis of ammonia . The industrialist Carl Bosch then succeeded in finding a process that enabled the mass production of ammonia. The Haber-Bosch process named after these two people is still the basis for the production of synthetic nitrogen fertilizers.
Nitrates
Naturally occurring deposits contain potassium nitrate (potassium nitrate) and sodium nitrate (sodium nitrate), for example in Chile - hence the colloquial name Chile nitrate . These deposits were mainly mined in the first half of the 19th century. Other sources are ammonium nitrate and ammonium sulfate . With the Haber-Bosch process or the Ostwald process , nitrogen fertilizers can be produced synthetically.
Phosphates
For a long time, the natural product guano was also the main source of phosphate fertilizers . On the Pacific island of Nauru , the main export product was nauruit (phosphorite), the mining of which has continuously declined since the mid-1970s, the deposits are now exhausted.
Phosphates are used as raw phosphates or as digested phosphates. However, rock phosphates are sparingly soluble and are rarely used as fertilizer. That is why rock phosphates are digested with sulfuric acid or phosphoric acid . This creates calcium dihydrogen phosphate or, if sulfuric acid is used, calcium sulfate as well. Rock phosphate that is digested with sulfuric acid is called superphosphate . Triple superphosphate or double superphosphate is made from rock phosphate and phosphoric acid and has a higher content of phosphorus. CaNaPO 4 · CaSiO 4 is used as a long-term fertilizer . This is insoluble in water and is removed from the roots by organic acids. Nitrogen- containing phosphate fertilizers such as B. Diammonium phosphate (NH 4 ) 2 HPO 4 ( ammonium phosphate ) or monoammonium phosphate are made from ammonia and phosphoric acid.
Potash Salts
Potash salts often occur as compounds of nitrates or phosphates. They are extracted in the salt mine , processed or converted into potassium sulphate . Because of the chloride ions, however, potassium chloride is not very suitable as a fertilizer. Some fertilizers contain a mixture of potassium chloride and potassium oxide . Traditionally, potash fertilizer was added through plant ashes (see potash ).
Individual evidence
- ^ A b c Martin Bertau, Armin Müller, Peter Fröhlich, Michael Katzberg: Industrial Inorganic Chemistry . John Wiley & Sons, 2013, ISBN 978-3-527-33019-5 , pp. 171 ( limited preview in Google Book search).
- ↑ Christine von Buttlar, Marianne Karpenstein-Machan, Roland Bauböck: Cultivation concepts for energy crops in times of climate change Contribution to climate impact management in the metropolitan region of Hanover-Braunschweig-Göttingen-Wolfsburg . ibidem-Verlag / ibidem Press, 2014, ISBN 978-3-8382-6525-4 ( limited preview in Google book search).
- ↑ Organic fertilization and reduced tillage as control factors for the C, N, P and S storage of microorganisms . kassel university press GmbH, 2010, ISBN 978-3-86219-033-1 , p. 86 ( limited preview in Google Book search).
- ^ Franz Schinner, Renate Sonnleitner: Soil cultivation, fertilization and recultivation . Springer-Verlag, 2013, ISBN 978-3-642-80184-6 , p. 179 ( limited preview in Google Book search).
- ↑ Application note for 60er Kali , K + S AG.
- ↑ Data sheet 60er Kali , K + S AG.
- ^ Römpp Lexikon Chemie , 9th edition 1990, page 2119 f.