Hi Rama

I am not sure if I am understanding your question correctly, but nevertheless, here's my 2 cents. Yes indeed, It is is also related to microbial population. From a soil biology perspective, If a soil is very good at retaining water (has high water holding capacity), that would influence the activity of your microbes in the soil, which in turn help to improve your soil fertility and structure through the process of decomposition of OM which then results in more CO2 release from the soil surface as well as improving your soil porosity through soil mixing. Remember moisture and temperature play a huge role in the activity of your organisms in the soil. In terms of the fertility itself, better structure will directly influence your soils nutrient holding capacity  which then improves your fertility.

Dear Rama Kant Dubey; Please go through the attachment. They may be very useful to your research. Thanks

https://dl.sciencesocieties.org/publications/sssaj/abstracts/67/6/1888

http://onlinelibrary.wiley.com/doi/10.1111/j.1529-8817.2003.00761.x/full

Hi Rama

I am not sure if I am understanding your question correctly, but nevertheless, here's my 2 cents. Yes indeed, It is is also related to microbial population. From a soil biology perspective, If a soil is very good at retaining water (has high water holding capacity), that would influence the activity of your microbes in the soil, which in turn help to improve your soil fertility and structure through the process of decomposition of OM which then results in more CO2 release from the soil surface as well as improving your soil porosity through soil mixing. Remember moisture and temperature play a huge role in the activity of your organisms in the soil. In terms of the fertility itself, better structure will directly influence your soils nutrient holding capacity  which then improves your fertility.

Micro organism plays vital role in carbon fixation because of important carbon sequester enzymes, in presence of water content  and carbonic anhydrase enzyme, carbon dioxide is converted into bicarbonates.

Nutrient elements are available in solution, so different elements can become unavailable in different phases of the drying cycle, and some microbes are more resistant to dessication than others.

WHC is positive related with soil CO2 efflux as far as the temperature is around the biologically optimum and soil moisture is near field capacity so as substrate and air is ready for microbial population.

http://agrometeorologia.it/documenti/Aiam2012/55_Romolo.pdf

Rey, A., C. Petsikos, P.G. Jarvis and J. Grace. 2005. Effect of temperature

and moisture on rates of carbon mineralization in a Mediterranean

oak forest soil under controlled and field conditions. Eur.

J. Soil Sci. 56:589–599.

Almagro M, Lopez J, Querejeta M, Martìnez-Mena M, 2009.

Temperature dependence of soil CO2 flux is strongly modulated

by seasonal patterns of moisture availability in a

Mediterranean ecosystem. Soil Biology and Biochemistry,

41, 594–605

Ciao

Hello Rama ji,

Here is my answer :

The soil which has more WHC will have fine texture, in turn more nutrient holding capacity; hence first part is clear.

Secondly, in soil where Water Content is higher, the respiration of microbes ceases,  and even moisture may act as a barrier  for exchange of CO2 between soil and atmosphere; at somewhere near PWP towards FC, the microbial  respiration would be higher, in turn the CO2 concentration.

This is my answer as per my understanding

If  you find it ok, reply with comments

to this mail

Dear  Rajakumar,

Thank you very much for the explanation. Can you kindly provide the articles related with your answer. 

http://www2.ca.uky.edu/agc/pubs/agr/agr204/agr204.pdf

Dear Rajakumar,

Thank you very much for sharing the PDF.

Dear All,

Thank you very much for your nice answers.

Thanks a lot.

Hello Rama Kant Dubey ji,

Pl ask any soil science related questions to me. I will try to explain if not I will collect information from elsewhere and provide you!

Thanks

Regards