Hi Bhavana Arora ji; Following links may be useful to you.

http://genome.cshlp.org/content/13/11/2467.short

http://ieeexplore.ieee.org/xpls/abs_all.jsp?arnumber=934080

Thanks

I can speak specifically to biogeochemical cycling in bodies of water and watersheds

I'm familiar with a few models that look at nitrogen loading and/or transport across watershed scales - for example the Nitrogen Loading Model (NLM) or SPARROW.   There are plenty of models like this out there....SPARROW seems to be commonly used.  As for techniques aside from modeling, there are monitoring networks that look at nutrient concentrations, but scaling up processes such as fixation, sequestration, transformation etc....this is a real issue and is not easily done.  It may just depend on your system and how much these processes have been measured/studied.

Thank you Sarwan ji for useful links. I'll definitely have a look at these publications.

Leanna Heffner, thank you for agreeing with the importance of this issue. We had a meeting a few weeks ago to look at recent techniques for upscaling biogeochemical cycles, which have many processes and interactions. So, what you are emphasizing for nitrogen is so true.