check out chapter 5 (section B) of the first edition of the Handbook of soil science, chapter on Redox Phenomenon by BR James and RJ Bartlett (I am not sure if this same chapter and its contents are in the second edition).
parts of the handbook are available in google books
http://books.google.com/books?id=iP7LWpn5oJ0C&pg=SL2-PA175&lpg=SL2-PA175&dq=ph+soil+gibbs+free+energy&source=bl&ots=rWLCG1X-PB&sig=9hE7RoDTEluh63cR_-3hfcEbjkY&hl=en&sa=X&ei=WEXDU_6NLoSUyASyn4CgDA&ved=0CDUQ6AEwBA#v=onepage&q=ph%20soil%20gibbs%20free%20energy&f=false
I am also going to recommend a really good book on NItrification
Ward, Bess B., Arp, Daniel J., and Klotz, Martin G., eds. Nitrification. Washington, DC, USA: ASM Press, 2011. ProQuest ebrary. Web. 12 September 2014.
But a short answer...
Nitrifying organisms obviously contain membrane bound enzymes to oxidize ammonia to nitrite, while other organisms will further oxidize nitrite to nitrate. The first step in the catabolic process is a protein super unit called the ammonia monooxygenase (AMO). This structure converts NH3 to NHOOH (hydroxylamine) and is substrate specific, in other words it can not process the Ammonium Ion (NH4+), this is one of the many reasons that soil pH has an effect on soil nitrogen cycles (with the caveat that there has been reported Archaea that are capable of utilizing NH4+ (although the mechanism is still unknown at least to my knowledge). But I would take at that book.
hope that helps a little
First you should know it is not PH, the correct is pH
the pH is a way to measure the acidity or alkalinity of the soil. Soils have pH values above 7 are alkaline and below that number they are acidic. Soil pH affected on micro-organisms activity, plant growth, availability of nutrients etc.......
you will find several books about this issue
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- Similar topics
- Biological Science
- Biochemistry
- Biochemical Techniques
- Analytical Chemistry
- pH