Compost barn manure with carbon-rich bedding at roughly 3 parts carbon to 1 part manure by volume, turn the pile every 2-4 weeks, and expect finished, earthy-smelling compost in 3-6 months. A pile turned that rarely stays cooler than a hot-composted one and is not proven free of pathogens, so keep it off food crops until it has been heated or aged.
Part of Manure Management
Collection and composting is the gathering of manure and soiled bedding from the barn and the controlled rotting of that mixture into stable fertilizer.
Time And Heat Make Compost Safe, And This Schedule Mostly Offers Time
Manure composted for 3-6 months becomes stable fertilizer. It turns from a smelly, wet heap into something that smells earthy, not like manure. That slow route is easy labour: pile it, turn it every 2-4 weeks, wait. What it does not do reliably is kill disease organisms. Pathogen kill needs sustained heat, and a pile turned only every few weeks may not hold it long enough.
Two routes exist. The slow pile described here is low-labour and low-certainty. The hot method in Hot Composting (a pile at least 90 × 90 × 90 cm turned on a tight schedule and holding 55 °C) is the faster, more reliable route. Composting and Compost Maturity cover the science and the checks.
What You Need
- Manure and soiled bedding collected from the barn
- Carbon: straw bedding, leaves or wood shavings
- A flat, firm, drained base downhill and downwind of buildings, at least 30 m from any water source, reachable by cart
- A fork, a thermometer or a metal rod to feel the pile’s heat, and a way to keep rain from soaking it
Method: Build And Turn A Pile
Step 1: Collect. Scrape stalls and pens daily or clear a deep litter pack as described in Bedding Systems.
Step 2: Layer manure and carbon. Mix about 3 parts carbon to 1 part manure by volume.
Step 3: Size the pile. A pile too small cannot hold heat; the pile in Hot Composting is the minimum for sustained heat.
Step 4: Turn on schedule. Turn every 2-4 weeks, bringing the cold outside of the pile into the middle.
Step 5: Check the heat. A pile that never warms is too dry, too small or has too little manure; one that smells of ammonia has too little carbon.
Step 6: Judge when it is done. Finished compost smells earthy, not like manure. Allow 3-6 months.
Step 7: Wait before food crops. This slow pile is not proven to kill pathogens. Organic-farming standards in the United States (recalled, not checked here) require at least 90 days between applying raw manure and harvest for crops whose edible part does not touch the soil, and 120 days where it does. Treat those as the minimum for raw manure, and apply the same waits to compost that was never heated, since it has no proven margin over raw manure.
Worked Example
The 3:1 mix by volume means 4 parts in total, of which 3 are carbon and 1 is manure. To make a 1.0 m³ pile: manure = 1.0 × 1/4 = 0.25 m³ and carbon = 1.0 × 3/4 = 0.75 m³. Check: 0.25 + 0.75 = 1.0 m³. A 1 m³ pile is just above the 90 × 90 × 90 cm cube of Hot Composting (0.9 × 0.9 × 0.9 = 0.729 m³), so it is large enough to hold heat if the manure is wet enough and the pile is turned often.
Turns over the composting period: 3 months is about 13 weeks, and turning every 4 weeks gives 13 / 4 = 3.25, so 3 turns. 6 months is about 26 weeks, and turning every 2 weeks gives 26 / 2 = 13 turns. The schedule therefore runs from about 3 to 13 turns.
Common Mistakes
- Treating “3-6 months” as proof of safety — time alone does not guarantee pathogen kill.
- Too little carbon — the pile goes wet and smelly and gives off ammonia.
- Siting beside a well — the leachate follows the slope.
- Stirring a covered or deep wet store with people inside the building — see the gas hazard below.
Safety
Manure gas and sealed stores
A covered or enclosed manure store, a deep wet pack and an under-floor channel generate hydrogen sulphide (heavier than air, pooling at floor level and in pits), ammonia, methane and carbon dioxide. Hydrogen sulphide deadens the sense of smell at dangerous concentrations, so “I can no longer smell it” means the gas is getting worse, not better. Turning or emptying a store releases a slug of it.
Do not turn or empty a covered store with anyone inside the building; open all doors and vents and stay out until it has cleared. Never climb into a pit or tank: a worker who collapses cannot be pulled out by someone climbing in after them. Two people, one outside; a harness and line; retrieve from above. Do not test the air with a flame.
What’s Next
- Learn next: Manure Use — applying the compost
- Combine with: Bedding Systems — what goes into the pile