Fertilization nitrogen flux

Figure 6b. Modeled versus observed river nitrogen export for same set of regions as in Figure 6a. The model is a multiple linear regression of river nitrogen flux against agricultural inputs (fertilizer, plus nitrogen fixation by leguminous crops, plus net import or export in food and feed) and inputs from combustion of fossil fuels (anthropogenicFlOy deposition) (Howarth, 1996).

Feedbacks may be affected directly by atmospheric CO2, as in the case of possible CO2 fertilization of terrestrial production, or indirectly through the effects of atmospheric CO2 on climate. Furthermore, feedbacks between the carbon cycle and other anthropogenically altered biogeochemical cycles (e.g., nitrogen, phosphorus, and sulfur) may affect atmospheric CO2. If the creation or alteration of feedbacks have strong effects on the magnitudes of carbon cycle fluxes, then projections, made without consideration of these feedbacks and their potential for changing carbon cycle processes, will produce incorrect estimates of future concentrations of atmospheric CO2. 

Figure 3. The general nitrogen model for illustrating the bio geochemical cycling in Forest ecosystems. Explanations for the fluxes 1, ammonia volatilization 2, forest fertilization 3, N2-fixation 4, denitrification 5, nitrate respiration 6, nitrification 7, immobilization 8, mineralization 9, assimilatory and dissimilatory nitrate reduction to ammonium 10, leaching 11, plant uptake 12, deposition N input 13, residue composition, exudation 14, soil erosion 15, ammonium fixation and release by clay minerals 16, biomass combustion 17, forest harvesting 18, litterfall (Bashkin, 2002).

Nitrate. Sodium nitrate, nitrate of soda, Chile saltpeter, caliche, [CAS 7631-99-4], NaN03, white solid, soluble, mp 308°C. source in nature is Chile, in the fixation of atmospheric nitrogen HN03 is frequently transformed by sodium carbonate into sodium nitrate, and the solution evaporated. Used tl) as an important nitrogenous fertilizer, (2) as a source of nitrate and HNO3, (3) in pyrotechnics, (4) in fluxes,... 

Mosier A., Schimel D., Valentine D., Bronson K., and Parton W. (1991) Methane and nitrogen oxide fluxes in native, fertilized, and cultivated grasslands. Nature 350, 330-332. 

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