CARBON : NITROGEN
RATIO
Scientists speak of an ideal ratio of Carbon to Nitrogen of 30 to 1 (30:1), as measured on a dry weight basis. This is known as the C:N ratio. But DON'T GET CAUGHT UP IN THE NUMBERS. What's important is to understand how greens and browns affect the compost process and to use them to manage your compost system.
You can calculate the C:N ratio of your materials by using the chart below. For example, if you have two bags of grass clippings (C:N = 20:1) and one bag of leaves (C:N = 60:1) then combined you have a C:N ration of (20:1 + 20:1 + 60:1)/3 = (100:1)/3 = 33:1, which is pretty close to the ideal (C:N = 30:1).
|
Material |
C:N Ratio |
|
Coffee Grounds |
20:1 |
|
Corn Stalks |
60:1 |
|
Cow Manure |
20:1 |
|
Fruit Wastes |
35:1 |
|
Grass Clippings |
20:1 |
|
Horse Manure w/ Litter |
60:1 |
|
Leaves |
60:1 |
|
Newspaper |
50-200:1 |
|
Oak Leaves (Green) |
26:1 |
|
Peat Moss |
58:1 |
|
Pine Needles |
60-110:1 |
|
Rotted Manure |
20:1 |
|
Sawdust / Wood |
600:1 |
|
Sawdust Weathered for two months |
325:1 |
|
Straw |
80-100:1 |
|
Table Scraps |
15:1 |
|
Vegetable Trimmings |
12-20:1 |
|
