Compost: carbon/nitrogen balance

Green-to-brown material ratios → mix C:N and time to finished compost

Material

parts by volume

  • Fresh grass/weeds C:N 15
  • Kitchen scraps C:N 15
  • Manure (cow/horse) C:N 15
  • Poultry manure C:N 10
  • Fallen leaves C:N 60
  • Straw/dry hay C:N 80
  • Sawdust C:N 400
  • Cardboard/paper C:N 350

Mix C:N

ideal 25–30:1

27,7:1

Optimal — hot compost in 4–8 weeks

Greens in mix
40%
Hot (turned)
4–8 wk
Cold (unturned)
6–18 mo

C:N is by dry weight; volume parts are approximate (moisture changes weight). Pile ≥1 m³, damp as a wrung sponge, covered.