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Making a good compost requires the right Carbon-Nitrogen ratio of the mixture. But most of the compostable household wastes don't have an ideal 25-30:1 ratio and we call them "greens" or "browns". And each of those has a different C:N ratio and that's why a different amount of each material is needed to achieve the same balancing effect. What are the Carbon-Nitrogen ratios of most common household "greens" and "browns"?

The C:N ratio is always some kind of average but I'd like to see some scale of strong "browns/greens", medium and week ones.

  • 5
    Here's a good link to get you started. I will try to write a full answer later, when I have more time. – THelper Oct 21 '13 at 9:05
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I've compiled a list of common household wastes and their reported C:N ratios with links to the various sources. A difficulty is that different sources sometimes list different C:N ratios for the same material. This probably has to with differences in samples (e.g. one batch of fruit wastes versus another), but if you look at some of the bigger differences it may just be that some numbers are plain wrong (perhaps the 150 of cardboard?). When I found multiple conflicting numbers for a food source I placed what I think is the most credible value at the top.

Waste               Amount of C to 1N   Reference
------------------------------------------------------------------------------------------
Urine               0.8                 [1] 

Fish wastes         2.5 - 5.5           [2]

Soybean meal        4 - 6               [3]

General food waste  14 - 16             [3]
                    17                  [4]
                    20                  [5]

Vegetable wastes    11 - 19             [6] 
                    25                  [5] 

Grass clippings     9 - 25, avg 17      [3]

Coffee grounds      20                  [5]
                    25                  [4]

Garden weeds        20                  [4]
                    30                  [5]

Nut shells          35                  [4]

Fruit wastes        20 - 49, avg 40     [3] 
                    15                  [1]

Shrub trimmings     53                  [3]

Garden leaves       40 - 80, avg 54     [3]
                    60 - 80             [4]

Straw               48-150, avg 80      [3] 

Pine needles        80                  [5]

Paper               125 - 180           [2]

Sawdust             200 - 750, avg 442  [3]

Newspaper           398 - 852           [3]
                    170                 [1]
                    175                 [5]

Cardboard           563                 [3]
                    350                 [5]
                    150                 [1]

Hardwood chips      451 - 819, avg 560  [3]
                    400                 [5]
                    300                 [1]

Softwood chips      212 - 1313, avg 641 [3]

[1] http://www.epa.gov/reg3wcmd/pdf/foodwasterecovery.pdf

[2] http://www.norganics.com/applications/cnratio.pdf

[3] http://compost.css.cornell.edu/OnFarmHandbook/apa.taba1.html

[4] http://www.homecompostingmadeeasy.com/carbonnitrogenratio.html

[5] http://www.organicgardeningguru.com/composting-101/carbon-nitrogen-ratio

[6] http://oregonbd.org/Class/ftp/CtoN%20Ratios.pdf

  • 3
    1st time I see this table with references ! Well done, this should be on wikipedia. – X Tian Nov 8 '13 at 13:51

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