Soil microbial biomass is a key factor of soil nutrient dynamics, mainly in Agricultural land. I have collected samples from fields, which were Organic or compost manure treated and calculated total soil microbial biomass. I wanted to calculate the value of Biomass 'C' and 'N' separately. How could it be possible?
I have also calculated total organic Carbon and Nitrogen of soil.
I'm afraid you will need to perform some additional measurements. You can get the data you want following for example this protocol: http://allison.bio.uci.edu/protocols/microbiabiomasscn.pdf
Dear Dr. Tarasek, thanks for your kind attention but unfortunately, I am unable to perform the test, again...that's why I am asking the problem here..Is any numerical method available to estimate the value of microbial biomass Carbon and Nitrogen? When we have the value of total biomass, soil organic Carbon and Nitrogen too..
Dear Akshat,
unfortunately I am not aware of any method of this kind.
As far as I know, microbial biomass is usually up to 5% of the total OM, but I am not familiar with any equations that could be helpful in calculating how much exactly it is on a sole basis of the total value.
I don't know what is the reason why you cannot perform the additional tests - if this is because you have no more soil left, then nothing can be done, but if this is only a financial issue, than very cheaply (assuming you have equipment to measure respiration rate) you can get at least an estimate of microbial C, with the SIR method, however the method is old and criticized for its output only reflects "active" part of the microbial soil community, not the real biomass.
Or, if by any chance, you did PLFAs in your soils, you could get an estimate of microbial biomass from that...
Sorry, I can't help you more.
P.S. I am not a Dr. ...yet ;-)
Dear Tarasek,
Thank you so much for your advice! I will certainly go for for 'respiration rate'...Thank you so much..Indeed!!
Agata, if you measure microbial biomass using well-known fumigation-K2SO4 extraction procedure, you can determine dissolved C by either "dichromate oxidation" or an automated analyzer (liquid carbon analyzers, TOC) and dissolved N by either "Kjeldahl digestion" or "biomass NRN" measurements. These methods can give you a view of total biomass carbon and nitrogen separately depending on soil conditions or treatments. However NRN would give you ephemeral changes in biomass nitrogen pool (not changes in total biomass N), as it is reactive only to certain nitrogen forms.
Here is a nice reference you can find the methods for soil microbial biomass (click dowload lab manual on upper left side);
http://www.rothamsted.ac.uk/aen/smbweb1/methintro.html#
Best wishes
CAN
Dear Oguz
Can you again send the link, as this link you have attached is not working.
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