Answer: Sawdust has an extremely high ratio of carbon to nitrogen. It's 300-500:1. What that means is it takes a long time to break down, as the microorganisms that are doing the decomposing of organic matter like a carbon to nitrogen ratio of 30:1. It doesn't mean that it won't decompose, but you would need to mix it with a great deal of material high in nitrogen to try and balance it out, or use it sparingly as your carbon source. And, you'd probably have to keep adding more nitrogen to keep the process going. Materials high in nitrogen include grass clippings, manure and fresh green garden trimmings or kitchen scraps. Sawdust makes a good mulch for garden paths because it is slow to break down. You could use it as the base for paths and spread something more attractive over it. I hope this info helps!
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