Techniques for Using Hay Moisture Testers

Techniques for Using Hay Moisture Testers

June 26, 2009

Getting hay baled at the correct moisture can be difficult, especially when it is cloudy or humidity is high. Hay moisture testers are increasingly being used as a guide. To get the most effective and accurate results, you'll want to understand how they work.

These electronic tools can be poked into either a bale or windrow to measure the moisture content of the hay. They work by measuring the electrical resistance of the hay between two sensors. The more moisture, the less resistance. They then convert this resistance to a value associated with average moisture content.

While these tools can be effective, it's very risky to blindly believe the numbers provided. This doesn't mean that hay testers can't be trusted. It means that you, as the operator, need to know

  • how the tester works,
  • what causes values to vary, and
  • how to use the tester most effectively.

Several factors can influence how testers sense moisture. For example, tight or dense bales, or even areas within a bale, will give different results than looser hay. Wiggling the probe or inserting it at an angle versus straight into the bale changes the value. And hay with dew moisture gives much different values than hay without dew even when overall moisture content is the same.

While this sounds like testers can't be trusted, they can help if you take the time to use them for a while and learn what readings and what conditions indicate when to bale and when not to bale.

With experience, you can interpret readings accurately and get the guidance you need.

Bruce Anderson
Extension Forage Specialist