Urease inhibitors

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Uease inhibitors are chemical compounds that reduce or prevent the activity of the urease enzyme . Chemically, they are phosphoric acid diamides , phosphazenes and thiols , as well as derivatives of hydroxamic acid and urea . The areas of application are in agriculture , medicine and basic research on the mechanism of inhibition.

Even heavy metal ions (most silver , mercury , copper ) and potassium inhibit urease, can, however, due to their toxicity are not used. The application of ammonium thiosulphate fails due to the dependence on soil properties, which makes the result unsafe.

Examples

application areas

Loss of nitrogen after application of fertilizer

Urea is the most commonly used nitrogen fertilizer . When used normally as a component of fertilizer, the urea activity of soil bacteria causes the urea to break down into ammonia and carbon dioxide , some of which are released into the air, causing 15 to 35 percent of the nitrogen to be lost from the soil. This can not only be reduced by adding urease inhibitors; At the same time, these delay the availability of nitrogen so that no over- nitrification occurs.

Several efficient urease inhibitors, however, inhibit further plant enzymes, so that there is not necessarily an overall improvement. NBTPT has been shown to greatly reduce the soil's absorption capacity for methane ; the mechanism involved is unknown. In addition, there is sometimes the risk that toxic quantities of urea (for the plants) can collect in parts of the plant.

Loss of nitrogen in stored fertilizer

During the storage of solid manure and liquid manure , nitrogen losses occur due to urease activity. Here urease inhibitors such as PPDA and NBTPT are added in order to achieve a long-term shelf life.

Ammonia emission from manure

Ammonia is harmful to the environment in several ways and there are agreements on emission limits . Since around 80 percent of ammonia emissions (based on figures in Germany from 2005) come from agricultural animal husbandry, there is a possibility of using urease inhibitors. This is therefore more promising than with fertilization, because the conditions in the barn can be better controlled. A 50 percent reduction in emissions has already been achieved in tests.

Pathological urease-positive germs

Uease inhibitors are used medicinally to combat germs that metabolize urea: Helicobacter pylori in the stomach and Proteus , Klebsiella and others in the urinary tract. In both cases, ammonia excretion is necessary for the survival of the bacterium, and the inhibition of urease would be the method of choice, in addition to the general use of antibiotics. The two drugs approved by the FDA, acetohydroxamic acid and hydroxyurea , are known to have severe side effects.

Individual evidence

  1. ↑ a b c Martin Leinker: Development of a principle solution for reducing ammonia emissions from livestock stalls with the help of urease inhibitors. Diss. Martin Luther Univ. Halle-Wittenberg 2007. urn : nbn: de: gbv: 3-000012809 (PDF)
  2. ^ A b Franz Schinner, Renate Sonnleitner: Soil ecology: Microbiology and soil enzymes Volume III: Plant protection products, agricultural additives and organic environmental chemicals. Springer, 1997. ISBN 3540610251 , pp. 10ff.
  3. ↑ Gerok, Wolfgang / Huber, Christoph / Meinertz, Thomas / Henning Zeidler (eds.): The internal medicine: reference work for the specialist. 11th edition Schattauer Verlag, 2006. ISBN 3794522222 , p. 789
  4. ^ Marshall L. Stoller, Maxwell V. Meng: Urinary stone disease: the practical guide to medical and surgical management. Humana Press, 2007 ISBN 1588292193 , pp. 316ff