Mineralization nitrogen cycle

Being on-farm emissions (from cultivation and animals breeding) the most important source of GHG in food life cycle, numerous studies have tried to reduce them. Ahlgren [55] has used LCA to evaluate the use of biofuels in tractors and the substitution of mineral nitrogen fertilizers. This implied that 3-6% of a farm s available land was needed to produce the required biomass (to produce biofuels and fertilizer). 

Goh KM, Haynes RJ (1986) Nitrogen and agronomic practice. In Haynes RJ (ed) Mineral nitrogen in the plant-soil system. Academic Press, Orlando, pp 379—468 Golchin A, Oades JM, Skjemstad JO, Clark P (1994) Soil structure and carbon cycling. Aust J Soil Res 32 1043-1068... 

Based on a review of published and grey literature on this issue, it can be concluded that the ban of mineral N-fertilisers and synthetic pesticides on the one hand, and the low level of nitrogen cycling within the farm because of low livestock densities on the other, are important contributions which organic farming makes to water protection. 

Hart, S. C. Firestone, M. K. (1991). Forest floor-mineral soil interactions in the internal nitrogen cycle of an old-growth forest. Biogeochemistry, 12, 103-28. 

FIGURE 1. Schematic view of biogeochemical nitrogen cycle 1, nitrogen fixation 2, mineralization 3, immobilization 4, nitrification 5, nitrate assimilation 6, dissimilatory nitrogen reduction 7, denitrification (Rosswall, 1982). 

From these results we can conclude that nitrogen is relatively available in soils of Tropical Rain Forest ecosystems and that forest soils mineralize and nitrify large amounts of nitrogen. P. Vitousek andR. Sanford have shown similar results earlier in 1986 studying nitrogen cycling in moist tropical forests. 

The role of mineral surfaces in the nitrogen cycle is still an open question. Surprisingly little research has been done in this area, and most of the results... 

With the many compounds of sulfur found in the atmosphere, in aquatic environments, and in soils and minerals, sulfur cycles through the biosphere in much the same way that nitrogen does. However, unlike the relative abundances of nitrogen—for which the atmosphere is the major reservoir—the relative abundance of sulfur in the atmosphere is small compared with its abundance in other environments. 

The ion exchangeable form of nitrogen (lEF-N) is the most active part of nitrogen in sediments, which plays an essential role in the nitrogen cycle. And the NO3-N was the dominant state in lEF-N in Jiaozhou Bay sediments. Factors influencing the distribution and concentrations of lEF-N in sediments include mainly temperature, salinity, pH, OC (organic carbon) and the characteristics of clay minerals, etc. The correlative coefficients of lEF-N and other sedimentary environmental parameters were calculated and tabulated in Table 3.29. 

Fig. 2.26 The biogeochemical nitrogen cycle. A ammonia synthesis (man-made N fixation), B oxidation of ammonia (indnstrial prodnction of nitric acid), C fertilizer application, D formation of NO due to high-temperature processes, E Oxidation of N2O within the stratosphere, F oxidation of NO within the troposphere, G ammonia deposition and transformation into ammonium, H biogenic emission, I biogenic N fixation, K denitrification, L nitrification, M assimilation (biogenic formation of amino adds), N mineralization. RNH2 organic bonded N (e. g. amines).

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