C:N ratio is a ratio between mass of carbon to mass of nitrogen in a given substance. Higher value indicates greater availability of energy source (CARBON) for the microbes while low value indicates lower availability of energy source to the microbial population. Value of C:N ratio affects the nutrient avaialability to the crop plants. For instance, under High C:N ratio, microbes use carbon as source of energy leading to multiplication at larger rate which causes immobilisation of available nitrogen and decreased availability to crop plants. But under low C:N ratio, lower level of carbon enhances mortality of microbes and release of immobilised nitrogen which through the process of mineralisations becomes availability to plants. Value of C:N ratio varies from substance to substance. For example, C:N ratio of an arable soil is 10-12:1 while that of legumes it is about 20:1.

In addition, C:N could also be used to measure the susceptability of an organic material to fermentation.

High C:N ratio indicates the lack of nitrogen while low C:N ratio indicates high nitrogen content. Lack of nitrogen would slow the digestion rate during fermentation due to the insufficient cells to maintain active microbial biomass. However, if the nitrogen content is too high in the C:N ratio, it can evolve ammonia, which is toxic to microorganisms and can completely stop the fermentation.

Best Regards,

SA Akeem.