A compost windrow is a long, aerated pile turned on a schedule. Its cross-section is set by the turner, its recipe by the feedstocks, and whether it is finished by a temperature rule written into regulation.
Compost windrow: dimensions, recipe and the rule
window CURING SEASONchecked 2026-09-16responsible Windrow Field Manual (a named masthead, not a person)
[['Width', '2.5–4.5 m', "Set by the turner's capacity, not by biology"], ['Height', '1.2–2.1 m', 'Below this it loses heat; above it the core goes anaerobic'], ['Initial moisture', '50–60% by weight', 'The squeeze test: a handful drips one or two drops'], ['Pathogen rule', '55 °C for 15 days, 5 turnings', 'The windowless static pile alternative to the time-and-temperature rule']]
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Why the pile is a row and not a heap
A heap has a core that cannot be reached by air and a surface that dries out. A row has a core that is thin enough for the turner to move and rotate, which is how air gets to the middle. The row shape is an aeration decision dressed up as a materials-handling decision.
| Dimension | Practical range | Set by | Consequence of getting it wrong |
|---|---|---|---|
| Width | 2.5–4.5 m | Turner width | Too wide and the core stays anaerobic |
| Height | 1.2–2.1 m | Turner and site | Too low and the pile cannot hold heat in winter |
| Length | As long as the pad | Site layout | Almost irrelevant to the process |
| Aisle spacing | Wide enough for the loader | Access | Too tight and the pad cannot be worked |
The recipe is a ratio, and the ratio is not a formula for success
The starting point is a carbon-to-nitrogen ratio near 30 to 1 by weight and a moisture near 55%. Getting there is a mixing problem: a nitrogen-rich material such as grass clippings or manure is blended with a carbon-rich one such as dry leaves, straw or woodchip. The woodchip also sets the structure, which is what keeps air moving through the row.
A pile that smells sour or like ammonia is telling you the ratio is off in a specific direction. Sour means anaerobic, so turn it and add structure. Ammonia means too much nitrogen, so add carbon. The smell is a measurement.
Boundary: the compost windrow is not the hay windrow and not the snow windrow
The hay windrow is losing water and the snow windrow is being stored. The compost windrow is being kept in a temperature band by turning. The shared word describes a shape, and the shape is the least important part of all three processes.
The misreading worth naming: treating the time-and-temperature rule as a single event. Reaching 55 °C once is not the rule; holding it for the number of days, with the number of turnings, is the rule, and the record is what an inspector will ask for.
A position the manual will argue
The manual holds that most small windrow operations fail on record-keeping rather than on process. The pile usually does reach temperature. What is missing is the log that shows it, which turns a compliant operation into a non-compliant one at the first inspection. A clipboard on the loader is a better investment than a second thermometer.
Where the numbers come from
- S1Temperature, Municipal Yard Waste Composting Operator's Fact Sheets, Cornell Universitysupports the temperature band a curing windrow has to hold
- S2Composting Ingredients, Municipal Yard Waste Composting Operator's Fact Sheets, Cornell Universitysupports the carbon-to-nitrogen and moisture starting targets for the mix
- S3Appendix B to Part 503, Title 40 — Pathogen Treatment Processes, U.S. Code of Federal Regulationssupports the time-and-temperature pathogen rule the row has to satisfy
- S4Appendix II to Part 257, Title 40 — U.S. Code of Federal Regulationssupports the facility standards that govern where a windrow may be sited
One link, one document. No home pages, no search results, no bare domains.
Put this page down Put this page down when you know the temperature your rule requires and how you will record it. The record is the deliverable.