The C : N ratio of saw dust is

The C : N ratio of sawdust is 225 : 1.
Organic matter that is deposited in marine sediments contains a key indicator as to its source and the processes it underwent before reaching the floor as well as after deposition, its carbon to nitrogen ratio.
A carbon-to-nitrogen ratio (C/N ratio or C : N ratio) is the ratio of the mass of carbon to the mass of nitrogen in organic residues.
It is other things that, be used in analyzing sediments and soil including soil organic matter and soil amendments such as compost.