Carcass Composting uide to Mortality Management on Michigan Cattle Farms 3 1) A carbon-to-nitrogen (C:N) ratio between 15:1 and 40:1. 2) A moisture content range of 40 to 60 percent. 3) A temperature range of 100 to 150 degrees Fahrenheit. 4) An oxygen concentration greater than 5 percent. 5) A pH range of 5.5 to 9.0. Carbon-to-nitrogen ratio