Abstract:
The C:N ratio is one of the main characteristics that describe the decomposition and
nutrient release pattern of organic sources. It gives an indication of N availability for
the process of biological degradation, and the degrease in this ration with
decomposing time has been widely reported as an indicator of decomposition
process. The change in C:N reflects the organic matter decomposition and
stabilization achieved during composting. Plant residues with high C:N ratio(>40)
are mineralized far more slowly than residues with the C: N ratio less than (40).
Amendments with low N concentration (high C/N) induce net N immobilization.
High quality litter can decompose faster in comparation with low quality litter. N
concentration can be a good predictor of decomposition rate in the initial stage of
litter decomposition. Organic amendments can be used as nutrient source for plants,
but their effect on nutrient availability depends on properties such as C/N ratio and
concentration of rapidly and slowly decomposable compounds. Addition of organic
materials with high N concentration (C/N < 20) results in net N mineralization.
Whereas amendments with low N concentration induce net N immobilization' The
C:N ratio appears to be a useful parameter to measure when attempting to predict the
effects of manure amendments on short-term N availability. Composting is an
aerobic and self-heating bioprocess with localized temperature, PH, oxygen,
moisture, and nutrient gradients, which create highly heterogeneous microniches of
distinctly adapted microbial populations. The yield effect of green manure in soil
depends on the amount of N in biomass, its release rate, the C/N ratio in organic
matter, soil N content and climate. Mature composts increase SOM much better than
fresh and immature composts due to their higher level of stable C. High amount of
OM in compost increased OC in both soil and cultivated soil because of plant
cultivation effect and increase of OM degradation in cultivated soil.
