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Smelly, slimy compost usually has too much nitrogen; a pile that never heats up has too much carbon. Enter what you’re adding — by bucket or by weight — and we’ll estimate the carbon-to-nitrogen (C:N) ratio and tell you which way to adjust.
Common materials
| Material | Type | Approx. C:N |
|---|---|---|
| Chicken manure | Green | ~10:1 |
| Grass clippings | Green | ~17:1 |
| Vegetable scraps | Green | ~19:1 |
| Coffee grounds | Green | ~20:1 |
| Horse manure with bedding | Green/brown | ~30:1 |
| Dry leaves | Brown | ~54:1 |
| Straw | Brown | ~80:1 |
| Cardboard, newspaper | Brown | ~350–400:1 |
| Sawdust | Brown | ~440:1 |
Values follow the Cornell Waste Management Institute’s compost C:N guidance; real materials vary.
FAQ
Why does the ratio matter?
Microbes use carbon for energy and nitrogen for growth, at roughly 25–30 parts carbon to 1 part nitrogen. Outside that range decomposition slows down or the pile loses nitrogen as ammonia (the smell).
How long until compost is ready?
A well-balanced, turned pile can be ready in 2–3 months; an unturned pile can take 6–12 months.
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