Nitrous oxide emissions, from soil

Bremner, J. M. and Blackmer, A. M., 1978 Nitrous oxide emission from soils during nitrification of fertilizer nitrogen. Science 199, 295-296. 

Methane emissions from enteric fermentation and nitrous oxide emissions from soils were the main drivers of GWP. 

Cai Z, Xing G, Yan X, Xu H, Tsuruta H, Yagi K, Minami K. Methane and nitrous oxide emissions from rice paddy fields as affected by nitrogen fertilisers and water management. Plant Soil. 1997 196 7-14. 

Furukawa Y, Inubushi K. Effect of application of iron materials on methane and nitrous oxide emissions from two types of paddy soils. Soil Sd. Plant Nutr. 2004 50 917-924. 

Hou AX, Chen GX, Wang ZP, Van Cleemput O, Patrick Jr WH. Methane and nitrous oxide emissions from a rice field in relation to soil redox and microbiological processes. Soil Sci. Soc. Am. J. 2000 64 2180-2186. 

DeKlein cam, McTaggaet IP, Smith KA, Stevens RJ, Harrison R and Laughlin RJ (1999) Measurement of nitrous oxide emissions from grassland soil using photo-acoustic infrared spectroscopy, long-path infrared spectroscopy, gas chromatography, and continuous flow isotope-ratio mass spectrometry. Commun Soil Sci Plant Analysis 30 1463-1477. 

Nitrous oxide emissions from well-aerated soils are not significantly correlated to soil nitrate content, bnt are very significantly correlated to nitrifiable nitrogen content (or their capacity to prodnce nitrate under aerobic conditions). 

Nitrous oxide emission from well-aerated soils is stimulated by the addition of nitrifiable forms of nitrogen (ammonium, urea, alanine, and other compounds), but is not significantly affected by nitrate and glncose (Table 8.7). 

Nitrous Oxide Emissions from Well-Aerated Soils... 

Nitrous oxide emissions are generally induced by fertiliser application. Emission strength varies with soil type, temperature and moisture and is substantially crop specific. There is a considerable difference between woody species and cereals. While the Intergovernmental Panel on Climate Change (IPCC) general N20 emission value is set to 1.25% of the nitrogen applied an average of 0.8 to 1.0% could be found from sandy soils. 

Nitrite formation may lead to nitrous oxide (N O) emission. An example of such a process under reclaimed efQuent disposal on the land surface is reported by Master et al. (2004). Irrigating a grumosol (<60% clay content) with fresh and reclaimed effluent water, it was found that, under efQuent irrigation, the amount of nitrous oxide emissions was double the amount emitted under freshwater treatment, at 60% w/w. The N O emission from efQuent-freated bulk soil was more than double the amount formed from large aggregates. 

Deep plough-based organic systems may increase energy consumption in agroecosystems (Kouwenhoven ef al. 2002), which is another important indicator of environmental impact. In contrast, mulch-based systems and systems in which manure is left on the soil surface or is shallowly incorporated would enhance N volatilisation losses to the atmosphere. However, compared to ploughing, shallow incorporation (rotovation) of an organic ley did not significantly increase cumulative nitrous oxide (N2O) emissions from soil (van der Weerden ef al. 2000). 

Although the estimated source strengths remain uncertain, emissions from soils appear to dominate the nitrons oxide bndget (IPCC, 1990). The main biogenic sources of nitrous oxide, NO, and N2 in soils are the microbial processes of denitrification and nitrification. 

Nitrous oxide, N2O 0.3 ppb Rising Uniform Emission from soils, 10 Emissions from oceans, 6 Anthropogenic, 9 Loss to stratosphere, 19 llOyr... 

Bouwman, A. F. (1996). Direct emission of nitrous oxide from agricultural soils. Nutr. Cycl. Agroecosyst. 46, 53-70. 

It is thought that little net NO is produced in denitrification, it being readily reduced to N2O, and nitrification is therefore the main source of NO (Anderson and Levine, 1986 Skiba et al, 1993). Nitrous oxide is also produced in both nitrification and denitrification. At low O2 concentrations in otherwise aerobic soil, small amounts of N2O are formed as a by-product of nitrification, N2O not itself being reduced to NO,. In denitrification, the proportion of N2O produced relative to N2 increases as the availability of O2 increases and that of carbon decreases (Tiedje, 1988). In general only a small fraction of the N nitrified or denitrified in these pathways is released as NO or N2O. The emission is therefore sensitive to the amount of mineral N in the system, which is driven principally by additions of nitrogen fertilizers and deposition of nitrogen from the atmosphere. 

Nitrous oxide is important not only as a greenhouse gas but, as discussed in Chapter 12, as the major natural source of NC/ in the stratosphere, where it is transported due to its long tropospheric lifetime (Crutzen, 1970). The major sources of N20 are nitrification and denitrification in soils and aquatic systems, with smaller amounts directly from anthropogenic processes such as sewage treatment and fossil fuel combustion (e.g., see Delwiche, 1981 Khalil and Rasmussen, 1992 Williams et al., 1992 Nevison et al., 1995, 1996 Prasad, 1994, 1997 Bouwman and Taylor, 1996 and Prasad et al., 1997). The use of fertilizers increases N20 emissions. For pastures at least, soil water content at the time of fertilization appears to be an important factor in determining emissions of N20 (and NO) (Veldkamp et al., 1998). 

In this case, N20 (called nitrous oxide or laughing gas) has natural sources, such as emissions from swamps and other oxygen-free ( anoxic ) waters and soils. The oxygen atoms in this reaction can come from several tropospheric photolytic reactions involving OH or OOH. Another source of NO is the thermal reaction between N2 and 02 ... 

Thornton FC, Bock BR, Tyler DD. 1996. Soil emissions of nitric oxide and nitrous oxide from injected anhydrous ammonium and urea. J Environ Qual 25 1378-1384. 

Breitenbeck, G. A., A. M. Blackmer and J. M. Bremner (1980). Effect of different nitrogen fertilizers on emission of nitrous oxide from soil. Geophys. Res. Lett. 7, 85-88. 

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