How To Use A Hay Moisture Tester

The consequences of harvesting, baling and storing hay with incorrect moisture levels are many and costly! Monitoring the moisture content of hay with a hay moisture tester is a quick and easy way to help prevent crop, revenue, and property loss.

There are different methods for measuring moisture with a hay moisture tester, so your Instrument Choice Scientists decided to check out the best methods. Here’s what they found.

Read on for the best ways to manage forage moisture content to create a safe, stable, and valuable product.

Why Use a Hay Moisture Tester?

Hay moisture has a direct and profound impact on hay quality. Where crop moisture is too high, the product will be less palatable, develop mould (and potentially mycotoxins), and in extreme cases, cause thermal expansion, which can lead to combustion. If the moisture content is too low, nutritional values reduce, hay volume reduces, and the final product becomes less palatable.

Hay Moisture Level Insights

1. Monitor hay moisture within a targeted range
Hay is heterogeneous in nature, so it’s a good idea to evaluate moisture levels within a range rather than aiming for a specific value.

2. ‘Ideal’ moisture levels

As a rule of thumb, hay baled at more than 20% moisture is at risk of overheating or going mouldy - which means poor nutritional quality feed. What’s worse, at 25 to 35% moisture (75 to 65% dry matter), spontaneous combustion (and so catastrophic crop loss) is likely to occur. At less than 18%, moisture nutrition, bale volume and palatability deteriorate.

3. Determining your ‘ideal’ moisture levels

Producing consistently high-quality feed is both an art and a science. Here’s just a taste of the variables affecting hay moisture content: 

• Harvesting and storage methods – the way you cut and spread your hay before baling, the model baler you use, your baling method, your final bale size and density, together with stacking and storage practices, will all significantly impact moisture and temperature. Say you opt to produce small, square bales. Compared to a large square or round bale, each unit will have a greater relative surface area and less density. Heat and moisture can escape more freely, and higher moisture levels are less problematic – within limits! However, if you stack your hay tightly and in tall piles, the risk of overheating increases.
• Ambient temperature & humidity – Warmer humid conditions can contribute to hay bales overheating. Conversely, if the prevailing air is too cool and dry, suboptimal hay quality may result.
• Additives – when baling hay at higher moistures (18%+), bacterial inoculants and hay preservatives provide ways to help preserve quality.
• Type and content of forage – each crop, whether alfalfa, orchard grass, lucerne, red clover, has a specific moisture content range for producing premium fodder.
• Other factors - variations in plant water-soluble carbohydrate (WSC) levels and types, changes in leaf surface due to moisture stress, and uneven drying affect bale moisture.

How to use a hay moisture tester in windrows

Most hay moisture meters cannot take accurate measurements directly from the windrow. The best practice is to pack loose hay into a 20-40 litre bucket. The higher the density, the easier it will be for your moisture meter to make contact and obtain an accurate reading.

Take a hay moisture measurement, then mix the hay in the bucket, recompact and remeasure. Repeat this test several times. Your hay moisture level will be the average of the taken readings.

Repeat these steps in several parts of the field, paying close attention to areas where your hay is spread thickest. 

How to use a hay moisture tester during baling

Baler units have a fixed sensor that connects to a digital screen within the cab.  The LCD screen will display the current and average moisture content in real-time. This valuable information provides the opportunity for swift corrective action when moisture levels are out of specification.

 How to use a hay moisture tester for bales

The exact method of testing bales will depend on the make and model of your hay moisture meter.

To take a measurement, insert the hay moisture tester into the bale and wait for a stable reading. Record the result and repeat the test several times across the same bale. Your final moisture content will be an average of your taken readings.

Watch a scientist measuring hay bale moisture content. 

Examples of Hay Moisture Testers 

Hfm II Hay Moisture Meter / Straw Moisture Meter 50cm Product code: AGFH0010   The AGRETO handheld hay and straw moisture meter HFM II is a professional measuring instrument for determining moisture levels and temperature levels in baled hay, straw, and silage.  The meter consists of a 50cm stainless steel probe and LCD screen covered in a dust and spray proof casing. The AGFH0010 hay moisture meter features an averaging function, count function, temperature measurement and automatic calibration for ease of use.  Also available with the following probe sizes: 100cm and 200cm  Specifications Moisture Range: 9 to 50% Moisture Accuracy: ±0.8% accuracy at low moisture levels  Use: Baled hay, straw, and indicative levels in silage.

Humimeter FL2 Hay and Straw Moisture Meter Product code: IC-humimeterFL2   The IC-humimeterFL2 is a portable, robust and professional hay and straw moisture meter designed for fast, stable and accurate moisture content measurements. Notable features include a 0.6-metre stainless steel probe, automatic averaging, an integrated memory and an included compression plate to enhance the measurement accuracy of bulk and unbaled materials.  A unique function is the capacity to log up to 10,000 points. You can download logged data to a computer via the units USB interface for further review, processing, and archiving.  Specifications Moisture Range: 8 to 60% water content (depending on the material) Moisture Accuracy: ±0.8% Use:

AGRETO PFM II Baler Mounted Moisture Meter Product code: IC-AGFP0010   The IC-AGFP0010 is a professional hay moisture content measuring instrument you can retrofit on almost any modern hay baler.  Constructed from sturdy materials and featuring a rugged splash and shockproof display unit, the IC-AGFP0010 will perform for many years of practical field use. The sensor takes measurements 25 times per second and displays the average in a user set interval or 1, 2, or 5 seconds, ensuring users can respond to any issues as soon as they arise.  Specifications Moisture Range: 9 to 70% Moisture Accuracy: 0.8% for lower moisture values Use: Baler units

Conclusion

Hay moisture has a substantial influence on hay quality. Our scientific team recommends you follow the advice we have outlined above to correctly use a hay moisture tester and produce a safe, stable, and valuable commodity.

Need a hand curating the best hay moisture testing solution for your needs? Speak with an Instrument Choice scientist! We're here to help! Call 1300 737 871 or email [email protected].