Sedgwick County

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