Dear Colegue

It is a very interesting question. By my experience water soluble organic C (WSC) is a fraction of organic C that is related very strongly with the potentially N mineralized in under anaerobic conditions (PMN). In addition Particulate organic Matter (POM) also can be related with N mineralization, but I think that this relationship is due to that POM and WSC are alsO related within they. So POM degradation will can liberate organic C fractions more asscesible to mineralization as those present in the WSC. In consequence when it is determine POM indirectely it estimated WSC present in the soil and the POM can show relationship with the rate of mineralization.  

Best regards

Also, I think C/N ratio is a very important indicator. In general, Dissolved Organic Carbon (DOC) and labile C pools (such as particulate organic matter, light fraction) are the most accessible to mineralization, However, I believe that it depend on different stabilization mechanisms of OC (physical inaccessibility, chemical recalcitrance and biotic mechanisms) that you have.

Congratulations for posing a nice question particularly relevant to soil fertility and conservation.

The most fundamental thing is the role played by diversity of carbon compounds. As stated earlier by experts, C/N ratio is an important factor. Passive and slow fractions are important for biophysical contribution and are of higher molecular weight than water soluble labile fraction which is important for nutrition (biochemical) function. So the latter fraction is most accessible to mineralization. Microbial component like fungal chitin is a polymer and so not easily accessible but important for soil aggregation. 

The microbial biomass C and particulate organic matter (4000-53µm)  can be very good indicator of SOM status and also  the most accessible to mineralization in many soils. But that also depends on soil itself. Best

Dear Colegue

It is a very interesting question. By my experience water soluble organic C (WSC) is a fraction of organic C that is related very strongly with the potentially N mineralized in under anaerobic conditions (PMN). In addition Particulate organic Matter (POM) also can be related with N mineralization, but I think that this relationship is due to that POM and WSC are alsO related within they. So POM degradation will can liberate organic C fractions more asscesible to mineralization as those present in the WSC. In consequence when it is determine POM indirectely it estimated WSC present in the soil and the POM can show relationship with the rate of mineralization.  

Best regards

Dr. Fernando PEREGRINA fits exactly; first at all, DOC is the most mineralizable fraction, mostly if this fraction has an adequate content of N. But inside POM can be integrated of lot of substances very different, ranging from very high C/N ratio to low C/N ratio.

But take care..., because you can have a negative picture: At lot of DOC can mean that you have a low microbiological activity in the soil, and vice-versa. Soil is a very complex system....

I am agree with Noelia and Marc that DOC  is the most mineralizable. C:N ratio is important factor.

Mineralization of carbon depends upon so many factors, however  if we consider only the substrate the labile carbon pools are easy to mineralize like DOC, POC, as well as hot water extractable carbon. In this quantity and quality of nitrogen as well as  C/N ration is very crucial to determine the process.

Beef and soil organic matter has the same C/N ratio around 10 in the arable situation, but they decompose at quite different rates in soil. This means that besides C/N ratio the accessibility to the microorganisms, which will decompose the two substrates has a lot of influence on the C release process. C left for any length of time in soil has become incorporated into quickly turning over microbial biomass, leaving mainly microbial cell walls and organelles to react with the surrounding older SOM and minerals. The outcome will vary with the situation at the individual site. In poor sites (higher C/N) more C mostly in hydrophobic fungal cell walls will be protected by H+ and polyvalent metal bridges (Fe and Al), while more fertile soil (lower C/N)will have more Ca bridges and a larger contribution of bacterial cell walls, which come in smaller pieces than fungal walls. To find something suitable to measure that correlates with C release, you should make clear to yourself what happens microbiologically in your soil. Do not forget that microorganisms turnover quite quickly!