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The combination of urea and ammonium nitrate has an extremely low critical relative humidity (18% at 30 °C) and can therefore only be used in liquid fertilizers. The most commonly used grade of these fertilizer solutions is UAN 32.0.0 (32%N) known as UN32 or UN-32, which consists of 45% ammonium nitrate , 35% urea and only 20% water.
Since urea is not an oxidizer at standard temperature and pressure, it is safer to handle and less of a security risk than other common nitrogen fertilizers, such as ammonium nitrate. However, if urea is applied to the soil surface, a meaningful fraction of applied fertilizer nitrogen may be lost to the atmosphere as ammonia gas; this only ...
Urea plant using ammonium carbamate briquettes, Fixed Nitrogen Research Laboratory, ca. 1930 Carl Bosch, 1927. The Bosch–Meiser process is an industrial process, which was patented in 1922 [1] and named after its discoverers, the German chemists Carl Bosch and Wilhelm Meiser [2] for the large-scale manufacturing of urea, a valuable nitrogenous chemical.
Urea is highly soluble in water and is therefore also very suitable for use in fertilizer solutions (in combination with ammonium nitrate: UAN), e.g., in 'foliar feed' fertilizers. For fertilizer use, granules are preferred over prills because of their narrower particle size distribution, which is an advantage for mechanical application.
The structure of the molecule of urea is O=C(−NH 2) 2.The urea molecule is planar when in a solid crystal because of sp 2 hybridization of the N orbitals. [8] [9] It is non-planar with C 2 symmetry when in the gas phase [10] or in aqueous solution, [9] with C–N–H and H–N–H bond angles that are intermediate between the trigonal planar angle of 120° and the tetrahedral angle of 109.5°.
In the U.K., fertilizer labeling regulations allow for reporting the elemental mass fractions of phosphorus and potassium.The regulations stipulate that this should be done in parentheses after the standard N-P-K values, as in "15-30-15 (15-13-13)".
Putrefying bacteria use amino acids or urea as an energy source to decompose dead organisms. In the process, they produce ammonium ions. Nitrifying bacteria then convert this ammonium into nitrate by oxidation, which can then be used by plants to create more proteins thus completing the nitrogen cycle. [6] This process is called nitrification.
Elevated nitrate in groundwater is a concern for drinking water use because nitrate can interfere with blood-oxygen levels in infants and cause methemoglobinemia or blue-baby syndrome. [28] Where groundwater recharges stream flow, nitrate-enriched groundwater can contribute to eutrophication , a process that leads to high algal population and ...