A few hens turn feed and kitchen scraps into a steady supply of rich, nitrogen-heavy fertilizer. The catch is that it is not ready straight out of the coop. Fresh chicken manure can burn plants, and like any animal manure it can carry germs you do not want on your lettuce. Turning it into safe, crumbly compost is not hard.
This is general information. For food safety questions specific to your garden, your county's Rutgers Cooperative Extension office is a good place to ask.
Why is fresh chicken manure too "hot" for plants?
"Hot" means high in nitrogen. Fresh chicken manure delivers so much of it, in such a raw form, that it can scorch roots and leaves. It also releases ammonia, the sharp smell of a damp coop.
Composting fixes both problems: microbes tie up the nitrogen in a more stable form, and a properly heated pile kills many weed seeds and disease organisms. Rutgers' guidelines for livestock in residential areas also say that poultry manure applied to a garden should be worked into the soil, not left on the surface as mulch.
Getting the carbon and nitrogen balance right
A compost pile needs "greens," high in nitrogen (manure, grass clippings, kitchen scraps), and "browns," high in carbon (wood shavings, straw, dry leaves).
North Dakota State University Extension puts the target for a manure compost pile at around 30 parts carbon to 1 part nitrogen, with a workable range of about 20 to 1 up to 40 to 1. When there is too much nitrogen, below about 20 to 1, nitrogen escapes and the pile smells of ammonia. When there is too much carbon, the pile just sits there.
The convenient part: your bedding is already a carbon source. NDSU lists straw and sawdust as very high in carbon, so used shavings or straw from the coop floor is already a mix of browns and greens. The University of Georgia's guide to composting poultry litter for backyard flocks suggests about 3 parts brown to 1 part green as a starting point.
Use your nose and your hands:
- Smells like ammonia? Add more shavings, straw or dry leaves.
- Dry, dusty and not heating up? Add water, or mix in fresh manure or green material.
- Right moisture: like a wrung-out wet rag, NDSU says. Moist, not dripping.
Sand does not break down, so keep it out. Our guide to chicken coop bedding covers which materials compost well and which to avoid in the first place.
Pile or bin?
Both work. It comes down to space, neighbors and how tidy you want it.
An open pile is the simplest. Pick a spot on level, well-drained ground, away from where water runs toward a well, stream or storm drain. Rutgers' residential livestock guidelines say manure can be stored in a covered, well-drained area 50 feet or more from the property line, so check your lot and your town's rules.
A bin keeps the pile neater and holds heat better. UGA suggests bins about 4 to 5 feet in each direction, which is big enough for the pile to heat up on its own. A two or three bin system, where material moves from one bin to the next as it breaks down, always leaves room for the next cleanout. Either way, cover it so rain does not wash nutrients out.
A pile of manure and old feed can draw rodents. Keep meat and greasy food scraps out of it, and keep it away from the coop itself. Our post on whether chickens attract rats covers the bigger picture.
How hot does the pile need to get?
Heat is what makes compost safe. The University of New Hampshire Extension's guidelines for manure-based compost say the pile needs to reach between 131°F and 140°F for a sustained period of several weeks, with regular turning so that all of the material spends time in the hot center.
A long-stem compost thermometer takes the guesswork out. When the center cools, turn the pile and it should heat up again. When it no longer heats after turning, and the material is dark, crumbly and smells like soil, it is finishing.
Small piles, cold weather and dry material keep a pile from heating. A pile that never got hot has not reliably killed pathogens.
How long should chicken manure age before using it on vegetables?
The USDA's National Organic Program rules (7 CFR 205.203) require raw manure to be composted unless it is applied to crops not meant for people to eat, or worked into the soil at least 120 days before harvesting a crop whose edible part touches the soil, or at least 90 days before harvesting a crop whose edible part does not touch the soil. Those rules are written for organic farms, but extension services such as UNH recommend the same timeline for home gardens.
UNH Extension's guidance for gardeners puts it plainly: wait at least 120 days after applying raw or aged manure before harvesting crops that grow in or near the soil, like root crops, leafy greens and strawberries, and at least 90 days for other crops. Note the word "aged." A pile that sat in the corner for a while but never got hot still counts as raw for this purpose.
UNH notes that animal manures can carry E. coli, Salmonella and Campylobacter, and advises washing vegetables and that people with weakened immune systems avoid uncooked vegetables from manured gardens. A few more habits:
- Wash your hands after handling manure, bedding or compost. The CDC advises washing with soap and water right after touching backyard poultry or anything in the area where they live.
- Keep fresh manure off growing plants and away from anything you are about to harvest.
- If your flock has been sick, talk to a veterinarian before that litter goes anywhere near the garden.
Why fall is a good time to clean out the coop
Most backyard flocks get a full cleanout in spring and fall; our guide on how to clean a chicken coop walks through it. Fall lines up well with the garden: beds are empty, next year's harvest is far off, and dry leaves supply the carbon. Litter worked into empty beds in fall has the winter to break down; just count the days from when it goes in to when you expect to harvest, and keep to the 120 and 90 day guidance.
Piles slow way down in a New Jersey winter, so a fall pile may not be finished by spring. Let it finish over the warm season.
How deep litter fits in
With the deep litter method, you add fresh bedding on top and let the bottom layer break down in the coop. By cleanout time it is partly composted, a head start, but not finished compost. Litter in a coop does not usually get hot enough, long enough, to count on for killing pathogens. Treat it like any other manure: put it through a hot pile, or work it in and respect the waiting periods before harvest.
Every coop we build is designed for deep litter, with a solid floor that is easy to clear out.
Thinking about a coop that makes cleanout easy?
We build custom coops, sheds and animal enclosures on-site across New Jersey, sized for your flock. See our coops, then tell us about your flock and your yard on our quote form, or call or text us at 973-846-1575.