Thoughts on Carbon\Nitrogen in Compost

When you compost, you are trying to convert raw plant carbons to stable humus, To do this you need to encourage microbes to eat the raw carbon and excrete stable carbon after digestion.  These microbes are made of protein and you need nitrogen to make proteins.

With this information we can start to understand the reason for the standard recommendation of 30 parts brown(carbon) to one part green(nitrogen).  You need to have sufficient nitrogen to support a robust population of microbes to produce warmth and eat(decompose) your raw plant carbons in a reasonable time frame.

If the amount of nitrogen is too high the population of microbes will grow so large that the oxygen diffusing into the pile is insufficient for air breathing microbes and non-air breathing microbes take over.  This is bad because non-air breathing microbes off-gas methane and Sulphur compounds which are smelly.  In addition Sulphur is an essential mineral for plants and it needs to remain in the compost.

So you can see that carbon is the primary ingredient in compost and the speed and final volume of the compost is determined by controlling the amount of nitrogen to control the population of microbes in your pile.