Carbon Nitrogen Ratio
First, let me apologize, as I have no doubt this topic has been addressed many times here. I've read a ton on the web and in the forums on this to try and get a good grasp of its understanding, but I'm still missing something.
I understand that you want to keep the ratio low in the compost pile to make it head up faster and hotter (say ideally 30:1). I also understand that you want browns in there too for the bacteria, and that the browns typically have a higher C:N ratio. If you just have greens to keep the ratio low, you'll just end up with stuff rotting and smelling from what I gather... no food for the bacteria (or not enough carbon).
What I can't figure out is how much brown to add depending on the type of brown. For example, say I have rotted manure (20:1) and vegetable cuttings (25:1) in a 50/50 mix to make this easy (I pulled the ratios from the web). I'm looking at a 22.5:1 ratio at that point, but have no browns.
Browns can be like straw (80:1) or sawdust (500:1). So now I have to decide to either put a small amount of straw, or an even smaller amount of sawdust in order to keep that ratio around 30 or 40 to one. A little algebra could find how much exactly to add to keep it at that ratio, but it seems like there'd be way too little brown mixed in to sustain the bacteria.
This would make for a tiny amount of browns compared with the greens, yet I also see many articles saying that you should have (generally) twice as many browns as greens. How can you have twice the browns and yet keep the C:N ratio down low?