You worked hard to grow a good crop. You timed your cutting, watched the weather, and put in the hours. But when you crack open that bale and it smells musty—or worse, looks like a biology experiment—you’re left wondering: What went wrong?
The answer is usually one word: moisture.
And the result is spoilage—something no hay grower wants to see.
Spoilage doesn’t just affect how your hay looks and smells. It can:
Lower the nutritional value of your crop
Cause health issues in livestock
Lead to wasted time, fuel, and money
Damage your reputation as a hay supplier
Let’s break down exactly how and why hay spoils—so you can stop it before it starts.
At moisture levels between 16% and 30%, mold, fungi, and yeasts start to multiply. These organisms feed on the sugars and nutrients in your hay, releasing heat as they grow.
You’ll often spot the signs:
White, dusty layers (mycelium and spores)
Musty odors
Dry matter loss
The risk of mycotoxins, which can harm livestock
Even if you don’t see visible mold, heat can quietly destroy your hay’s quality.
16–22% Moisture → Hay can reach 115°F or more in storage
Causes discoloration and a loss of that clean, grassy smell
23–26% Moisture → Temps rise above 120°F
Leads to dark, caramelized hay and reduced feed value
Over 27% Moisture → Hay may spike above 140°F
At this level, spontaneous combustion becomes a real danger
The good news? You can prevent most spoilage with better moisture control and preservation—right from the moment you bale.
At Harvest Tec, we offer tools that help you protect your hay before mold or heat can take over.
Know the exact moisture of your hay as you bale. Make smart, safe decisions without the guesswork.
Safely bale hay up to 30% moisture without spoilage. Baler’s Choice works by stopping microbial growth and preserving feed value—naturally, with no harmful chemicals. Learn more here.
Pair our tech with best practices: airflow, stacking methods, and regular checks to keep your hay stable and safe.
Spoilage may be common, but it’s far from unavoidable. With the right approach and the right tools, you can protect your hay—and your bottom line.
Explore more how-to articles and haymaking resources in our Haymaker Hub. It's your go-to spot for everything hay growers need to know.
Talk to your local Harvest Tec dealer or reach out to our team—we’re here to help you make hay that keeps its value, bale after bale.