In order to determine the amount of organic N mineralization in the soil, we need to determine soil mineralization constant (rate). Is it possible to estimate this parameter using easily available soil parameters or state variables, like particle size distribution and soil temperature?
Regards.
Dear Behnam
Denitrification may not be a good indicator for organic matter decomposition for a number of reasons with the exception of available organic-C. Denitrifiers may form a small part of the large microbial community that are responsible for the decomposition of the soil organic matter. Denitrifiers do rely on available-C for C fixing during the denitrification process where NO3-N or other oxidised form of N are reduced to N2O or N2. The available-C from decomposing OM could also be used by bacteria for biosynthesising NH4 (referred to as immobilisation).
Decomposition of OM is rapid under aerobic conditions than under anaerobic conditions. Under anaerobic conditions decomposition of OM promotes ammonification (NH4) production in soil, which in turn could be immobilised rather than being nitrified to NO3 form to be denitrified. On the other hand, decomposition under aerobic conditions may yield NO3 but may not provide conducive conditions (i.e. lack of O2) for denitrification.
If you however are still interested in denitrification coefficients, unfortunately there is no single reliable method available to estimate denitrification activity, apart from directly monitoring N2O/N2 losses. For example, while you can assess DEA (denitrification enzyme activity), the presence of enzymes may not always mean there will be corresponding denitirifaction rates. Whilst it could be argued denitrification potential may be greater when organic-C, soil moisture, To and clay particles are high, it is difficult to attribute denitrification rate to a single factor such as particle size.
Kind regards
Selva
Dear fellow, Sorry for the mistake I had made in the question. I have updated the text.
Dear Behnam
Soil N mineralisation depends mainly on the type of organic matter, C:N ratio and total-N. Lower C:N ratio promotes more mineralisation. While the above observation is a generalisation, net N mineralisation is a complex process. You may obtain more info in the following publication: https://www.researchgate.net/publication/269337951_An_evaluation_of_some_laboratory_methods_of_assessing_availability_of_nitrogen_in_agricultural_soils
Kind regards
Selva
Technical Report An evaluation of some laboratory methods of assessing availa...
I agree with the answers elaborated by Drs. Selva Selvarajah and Fulvio M. Rivano.
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