Growing

Compost C:N mixer

Get the carbon-to-nitrogen ratio right and the pile heats itself. Get it wrong and it either sits there or smells like ammonia.

Result

Material 1Straw (80:1)

Amount of material 13 parts by weight

Material 2Chicken manure (7:1)

Amount of material 21 parts by weight

Blended C:N ratio

61.8 : 1

Too much carbon. It will sit there cold for a year. Add greens or manure.

Target

25:1 to 30:1

Minimum pile size to hold heat

1 cubic yard (3 × 3 × 3 ft)

Smaller than this and it loses heat faster than it makes it.

Turn when the core hits

Above 150°F

Target 131–150°F. Above 160°F it's cooking itself.

What this will not do

This is an approximation on a weight basis, and real materials vary a lot with moisture. Treat it as a starting recipe, then let the thermometer tell you the truth.
131°F held for 3 days is the figure usually cited for killing weed seed and pathogens in a turned pile — and a long-stem thermometer is the only way to know, because the core is 18 inches in and the edge tells you nothing.
Moisture matters as much as ratio: a pile should feel like a wrung-out sponge. Too dry is the most common reason a correctly mixed pile does nothing.

The full build and the reasoning are in Chapter 21 of the guide.