Friday, August 21, 2026 / Eugene-Springfield / Lane County
The compost pile can make its own heat
Eugene-Springfield's fire chief says damp piles, stored hay and grain can build enough microbial heat to ignite.
A compost pile does not need a match to become a fire problem. Eugene Springfield Fire Chief Mike Caven told KLCC that damp compost, hay and grain can trap heat produced by microorganisms until the material ignites.
Moisture control and turning a compost pile help release that heat. For stored hay, Caven said people who manage it generally test moisture and keep it below 15 percent before stacking it in a barn. That number belongs to hay storage; it is not a universal rule for every pile of organic material.
The warning follows an Aug. 14 compost fire near Hendricks Park. Anyone who sees smoke, feels unusual heat or suspects a fire should move away and call emergency services rather than dismantling a hot pile by hand.
Field notes
What changed: Eugene Springfield Fire issued fresh prevention guidance after a local compost fire highlighted spontaneous-combustion risk.
Why it matters: Organic material can generate and trap heat without an outside flame, creating a hidden fire risk around homes, farms and storage buildings.
Who may be affected: Gardeners, farmers, stable operators and anyone storing compost, hay, grain or oil-soaked rags.