What are the two principal gases involved with soil aeration, and how do their relative amounts change as one samples deeper into a soil profile? If the redox potential for a soil at pH 6 is near...

What are the two principal gases involved with soil aeration, and how do their relative amounts change as one samples deeper into a soil profile?

If the redox potential for a soil at pH 6 is near zero, write two reactions that you would expect to take place. How would the presence of a great deal of nitrate compounds affect the occurrence of these reactions?