Nitrogen fixation abiotic

Although chemical reduction of N2 to ammonium by reaction with H2 gas is thermodynamically possible at room temperature, the reduction proceeds only at very high temperature. Consequently, abiotic nitrogen fixation is not feasible even in strongly reduced soils. 

The global nitrogen cycle is often referred to as the nitrogen cycles, since we can view the overall process as the result of the interactions of various biological and abiotic processes. Each of these processes, to a first approximation, can be considered as a self-contained cycle. We have already considered the biological cycle from this perspective (Fig. 12-1), and now we will look at the other processes, the ammonia cycle, the cycle, and the fixation/denitrification cycle. 

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