can you compost horse manure?
Yes — horse manure with its bedding is close to a balanced compost recipe by itself, but hot-compost it to kill the weed seeds it carries.
breaks down in 3–6 months hot, up to a year in a static heap
C:N ≈ 30:1
which bins can take it?
- hot pile yes
- cold pile caution
- worm bin caution
- bokashi no
- tumbler yes
- curbside caution
- cold pile: Fine for building soil, but expect weed seedlings — cool heaps never reach the 131°F that sterilizes them.
- worm bin: Age it a few weeks first and ask whether the horses were recently wormed — ivermectin residue in fresh manure kills composting worms.
- curbside: Livestock manure is usually excluded from residential carts even where yard waste is collected — confirm before hauling.
why?
Horses digest inefficiently, so their manure arrives loaded with partly broken-down fiber that microbes take to immediately, and the stall shavings or straw mixed in push the blend to roughly 30:1 — near the ideal starting ratio for a pile. That same lazy digestion passes viable weed seeds straight through, which is why cool-composted stable waste plants a crop of weeds in every bed it touches.
how to prep it
- Pile at least a cubic yard at once so the core can heat
- Wet it to the damp-sponge stage; stall waste is often bone dry
- Turn when the center cools to bring the outer layer through the hot zone
- Load a tumbler a few buckets at a time; a drum packed to the lid stops heating
watch out for
- Aminopyralid and clopyralid herbicides sprayed on hay pass through the horse and survive composting, then deform tomatoes, beans, and potatoes. Ask the barn what the hay was treated with, and run a bean-seedling test before using a large batch.
- Wood-shavings bedding raises the carbon load; if a pile of stall waste won't heat, it needs a nitrogen boost, not more browns.
- Fresh manure spread on food beds falls under the same 90- and 120-day pre-harvest waits that apply to any raw manure.
often confused with
- Aged manure pile at a barn — A heap that sat two years is weathered, not composted — it can still hold live weed seeds if it never heated.
quick answers
Is free horse manure from a stable worth hauling?
Usually yes, and barns are often glad to load it. The two questions to ask first are what bedding they use — avoid black walnut shavings — and whether their hay came from herbicide-treated fields.
How do I know if the pile got hot enough for weed seeds?
Use a long-stem compost thermometer and look for 131–140°F held three days in the core, then turn so every part takes a turn in the middle. That range is the published threshold for killing most weed seeds and pathogens.