Soils ammonia

Ammonia is one of the most important inorganic chemicals, exceeded only by sulfuric acid and lime. This colorless gas has an irritating odor, and is very soluble in water, forming a weakly basic solution. Ammonia could be easily liquefied under pressure (liquid ammonia), and it is an important refrigerant. Anhydrous ammonia is a fertilizer by direct application to the soil. Ammonia is obtained by the reaction of hydrogen and atmospheric nitrogen, the synthesis gas for ammonia. The 1994 U.S. ammonia production was approximately 40 billion pounds (sixth highest volume chemical). 

Only one study specifically compared volatilization losses between organic and conventional soil. Ammonia volatilization is mainly caused by animal manure rather than by N fertilizers (Kirchmann et al. 1998). 

In other titrations, the component to be titrated is separated from soil and subsequently titrated. The simplest of these is the determination of soil ammonia. However, all forms of nitrogen in soil are important, so methods of converting other nitrogen-containing compounds to ammonia, distilling it, and determining its concentration by titration are important. 

Apart from the economic significance of such loss there are potentially adverse effects on the environment arising from acidification of rain and soil. Ammonia may react with hydroxyl radicals in the atmosphere to produce NOx contributing to the acidification of rain (4). Wet and dry deposition of NH3/NH4+ inevitably contributes to soil acidification through their subsequent nitrification. This effect can be accentuated in woodland by absorption of aerosols containing NH4+ within the canopy followed by transport to the soil in stem flow (5). In more extreme cases, NH3 emission from feedlots, pig and poultry... 

The single largest use of ammonia is its direct apphcation as fertdizer, and in the manufacture of ammonium fertilizers that have increased world food production dramatically. Such ammonia-based fertilizers are now the primary source of nitrogen in farm soils. Ammonia also is used in the manufacture of nitric acid, synthetic fibers, plastics, explosives and miscellaneous ammonium salts. Liquid ammonia is used as a solvent for many inorganic reactions in non-aqueous phase. Other apphcations include synthesis of amines and imines as a fluid for supercritical fluid extraction and chromatography and as a reference standard in i N-NMR. 

In the atmosphere, ammonia is estimated to have a half-life of several days. The primary fate process is reaction of ammonia with acid air pollutants and removal of the resulting ammonium compounds by dry or wet deposition. Rain washout and reaction with photochemically produced hydroxyl radicals are also expected to contribute to the atmospheric fate of vapor-phase ammonia. In water and soil, ammonia will volatilize to the atmosphere and be removed by microbial processes, by adsorption to sediment and soil matrices as well as by plant uptake. 

In the atmosphere, ammonia can react with acidic substances in the air to produce ammonium aerosols, which can undergo dry or wet deposition. The best estimate of the half-life of atmospheric ammonia is a few days. In water, ammonia can volatilize to the atmosphere, be removed by microbial processes, or adsorb to sediment and suspended organic material. In soil, ammonia can volatilize to the atmosphere, adsorb to soil, undergo microbial transformation to nitrate or nitrite anions, or be taken up by plants. 

In soil, ammonia may either volatilize to the atmosphere, adsorb to soil, or undergo microbial transformation to nitrate or nitrite anions. Uptake by plants can also be a significant fate process. Ammonia at natural concentrations in soil is not believed to have a very long half-life. If ammonia is distributed to soil in large concentrations, the natural biological transformation processes can be overwhelmed, and the environmental fate of ammonia will become dependent upon the physical and chemical properties of ammonia, until the ammonia concentration returns to background levels. 

Ammonia volatilization is recognized as the major process by which nitrogen fertilizers are lost from paddy fields, especially when urea or other ammonium-based fertilizers are surface applied to the water column. In tropical climates, high water temperatures associated with algal activity in the water column are conducive to enhance volatilization of added fertilizers. Urea, a common fertilizer for rice in Asia, is rapidly hydrolyzed within the week after application to submerged soils. Ammonia originating from the hydrolyzed urea accumulates in floodwater, and the peak concentration of ammonia in the floodwater of tropical rice fields typically occurs within 1-5 days after urea... 

Because it is applied as a volatile liquid, anhydrous ammonia must be injected 15 to 30 cm below the surface of the soil this usually is accomplished by an application knife such as those shown in Figure 10.3. Often in sandy, loose soil ammonia is applied by an ammonia chisel, also shown in Figure 10.3. Anhydrous ammonia is usually metered by a variable orifice-type meter or by a piston pump, The rate of application using the orifice meter is determined by the speed of the applicator, the swath width, and the orifice opening. Piston pumps are usually actuated by a drive-chain operated by a sprocket attached to a wheel of the applicator. Application rate is changed by changing the length of stroke of the piston the rate is independent of the applicator s speed. 

For most crops, other than rice, urea in the soil must first undergo hydrolysis to ammonia and then nitrification to nitrate before it can be absorbed by plant roots. One problem is that in relatively cool climates these processes are slow thus plants may be slow to respond to urea fertilization. Another problem, more likely in warmer climates, is that ammonia formed in the soil hydrolysis step may be lost as vapor. This problem is particularly likely when surface appHcation is used, but can be avoided by incorporation of the urea under the soil surface. Another problem that has been encountered with urea is phytotoxicity, the poisoning of seed by contact with the ammonia released during urea hydrolysis in the soil. Placement of urea away from the seed is a solution to this problem. In view of the growing popularity of urea, it appears that its favorable characteristics outweigh the extra care requited in its use. 

The flexibility of the bulk blending system and the close relationship with the farmer allow the bulk blender to provide a number of valuable supplementary services, such as adding herbicides, insecticides, micronutrients, or seeds to the blends bagging blends liming and sampling soil. Consultation services and custom appHcation can also be provided as can sale of anhydrous ammonia or nitrogen solution. 

One-step clean-and-shine products have become popular in the household market. These products are appHed to the floor with a sponge mop and their detergent action removes and suspends soil, which coUects on the mop and is removed when the mop is rinsed with water. The formulation, which remains on the floor, dries to a poHsh film. An earlier product of this type was dispensed from an aerosol as a foam. Formulas as of this writing (ca 1995) are appHed as Hquids (29,30). In one product, the dried film obtained from the formulation is soluble in the formulation, which includes low molecular weight, high acid polymers and a fairly large amount of ammonia (31). Repeated use does not contribute to a buildup of poHsh. 

An additional mole of ammonium sulfate per mole of final lactam is generated duting the manufacture of hydroxylamine sulfate [10039-54-0] via the Raschig process, which converts ammonia, air, water, carbon dioxide, and sulfur dioxide to the hydroxylamine salt. Thus, a minimum of two moles of ammonium sulfate is produced per mole of lactam, but commercial processes can approach twice that amount. The DSM/Stamicarbon HPO process, which uses hydroxylamine phosphate [19098-16-9] ia a recycled phosphate buffer, can reduce the amount to less than two moles per mole of lactam. Ammonium sulfate is sold as a fertilizer. However, because H2SO4 is released and acidifies the soil as the salt decomposes, it is alow grade fertilizer, and contributes only marginally to the economics of the process (145,146) (see Caprolactam). 

Ammonium nitrate fertilizer incorporates nitrogen in both of the forms taken up by crops ammonia and nitrate ion. Fertilizers (qv) containing only ammoniacal nitrogen are often less effective, as many important crops tend to take up nitrogen mainly in the nitrate form and the ammonium ions must be transformed into nitrate by soil organisms before the nitrogen is readily available. This transformation is slow in cool, temperate zone soils. Thus, ammonium nitrate is a preferred source of fertilizer nitrogen in some countries. 

Sodium nitrate is used as a fertiliser and in a number of industrial processes. In the period from 1880—1910 it accounted for 60% of the world fertiliser nitrogen production. In the 1990s sodium nitrate accounts for 0.1% of the world fertiliser nitrogen production, and is used for some specific crops and soil conditions. This decline has resulted from an enormous growth in fertiliser manufacture and an increased use of less expensive nitrogen fertilisers (qv) produced from synthetic ammonia (qv), such as urea (qv), ammonium nitrate, ammonium phosphates, ammonium sulfate, and ammonia itself (see Ammonium compounds). The commercial production of synthetic ammonia began in 1921, soon after the end of World War I. The main industrial market for sodium nitrate was at first the manufacture of nitric acid (qv) and explosives (see Explosives and propellants). As of the mid-1990s sodium nitrate was used in the production of some explosives and in a number of industrial areas. 

Calcium cyanamide (lime nitrogen) has been used as a fertiliser (6). It hydrolyses ia moist soil to produce ammonia ... 

Following slow dissolution into the soil solution, oxamide undergoes stepwise hydrolysis to Hberate ammonia. Oxamic acid is formed in the first... 

The interest in gaseous losses of nitrogen from soil is now extensive and includes the well established community of soil scientists concerned with losses of fertilizer-applied nitrogen by nitrification and denitrification. More recently, interest in ammonia losses from plants and soil has been stimulated by the very large emissions from intensive cattle production in the Netherlands and their... 

Trees and soils of forests act as sources of NH3 and oxides of nitrogen. Ammonia is formed in the soil by several types of bacteria and fungi. The volatilization of ammonia and its subsequent release to the atmosphere are dependent on temperature and the pH of the soil. Fertilizers are used as a tool in forest management. The volatilization of applied fertilizers may become a source of ammonia to the atmosphere, especially from the use of urea. 

Environmental Fate. Ammonia combines with sulfate ions in the atmosphere and is washed out by rairtfall, resulting in rapid return of ammonia to the soil and surface waters. Ammonia is a central compound in the environmental cycling of nitrogen. Ammonia in lakes, rivers, and streams is converted to nitrate. 

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