Composting is a microbial process used to convert organic wastes to a solid product that can be used as a soil amendment. Composting systems perform best when the carbon to nitrogen ratio is in the range of 20-40 (C: N of 20:1 to 40:1). A poultry manure has a moisture content of 70%, is 6.3% N (on a dry mass basis) and has a carbon to nitrogen ratio (C: N) of 15 (also on a dry mass basis). The manure is to be composted with oat straw that has moisture content of 20%, is 1.1% N (on a dry mass basis) and has a carbon to nitrogen ratio (C:N) of 48 (also on a dry mass basis). How many kg of oat straw are required per kg of manure to attain a C: N = 30:1?