Hay Moisture & Spontaneous Combustion Risk Calculator

Assess spontaneous combustion fire danger, microbial heating peaks, and dry matter mold spoilage in hay bales based on moisture percentage, bale size, ambient conditions, and internal temperature probe readings.

Bale Specifications & Probe Readings

Hay Core Moisture (%) Measured via electronic probe or drying test

Bale Type & Size

Internal Stack Temp (°F) Core temperature probe reading (46.1 °C)

Days Since Baling Thermal peak occurs within first 5 to 21 days

Propionic Acid Preservative

Storage Location

Preset Monitoring Cases

Combustion Hazard Level Moderate Risk

Substantial Heating & Mold Spoilage

Inspect probe temperature twice daily; peak heating window active

Maximum Safe Moisture Threshold

≤ 16.0% Moisture

Excess: +2.0% above safe baseline

Estimated Dry Matter / Feed Value Loss

~4.5% DM Loss

Maillard browning (heat-damaged protein)

Thermal Status & Action Protocol

Core Probe Temperature: 115°F (Normal microbial respiration)

Action Recommendation: Monitor temperature daily. Stack is safe to remain stored.

Combustion Trigger Temp: 175°F (80°C) - Call Fire Dept immediately

Frequently Asked Questions

What should I do if my hay probe reads 160°F?

At 160°F (71°C), the hay is in critical thermal runaway. Alert your local fire department, do not walk directly onto the top of the stack without safety boards, and prepare water hoses before attempting to move bales.

How does propionic acid help prevent heating?

Buffered propionic acid acts as an antifungal mold inhibitor. It allows baling at 2–4% higher moisture levels by preventing initial fungal proliferation.

How long after baling is hay at risk of catching fire?

The highest risk period is 5 to 21 days after baling. After 30 to 45 days, if moisture has evaporated and temperature stays below 110°F, the stack generally cures safely.