Nitrogen fixation estimation

Larsson, U., Hadju, S., Waive, I, and Elmgren, R. (2001) Baltic Sea nitrogen fixation estimated from summer increase in upper mixed layer total nitrogen. Limnol. Oceanogr. 46, 811-820. 

Anonymous, Worldwide Nitrogen Fixation Estimated, Chem Eng. News, p.34,1976. 

Table 24.3 Estimates of the Total Annual Contribution of Combined Nitrogen to the Global Nitrogen Cycle by Nitrogen Fixation in Benthic Marine Environments. ...

Table 5.2 Estimates of biological nitrogen fixation (BNF) by various agents in wetland...

The process of nitrogen fixation is an essential part of the nitrogen cycle on the planet earth(l). It is estimated that greater than 60Z of the N2 that is ultimately converted to NH4+ is done so by the nitrogenase enzyme system. The availability of fixed nitrogen is often the limiting factor in plant growth( ). To... 

Boddey, R. M., and R. L. Victoria. 1986. "Estimation of biological nitrogen fixation associated with Brachiaria and Paspalum grasses using 5n labeled organic matter and fertilizer." Plant and Soil 90 265-292. 

Kustka, A., Sanudo-Wilhelmy, S., Carpenter, E. J., Capone, D. G., and Raven, J. A. (2003). A revised estimate of the Fe use efficiency of nitrogen fixation, with special reference to the marine N2 fixing cyanobacterium, Trichodesmium spp. (Cyanophyta). J. Phycol. 39, 12—25. 

Second, nitrogen fixation remains a poorly quantified process We need to better understand the relationship of the excess nitrate signals in the thermocline to nitrogen sources and sinks, and the role of physical transport, in order to determine if those signals truly (and primarily) represent N2 fixation in the overlying waters. There are large differences in the published estimates of N2 fixation in the North Atlantic. 

Figure 33.13 Hood et al. (2004) model-estimated nitrogen fixation rate in the mixed layer as a frmction of season. The fields are synoptic, from the middle of the specified month. The rates are expressed in mmol N m day Reproduced with permission from Hood et al. (2004).

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