Understanding Hay Conditions and Test Readings

Many variables affect the accuracy of sensor readings. Understanding these variables can help to make use of the sensor readings.

IMPORTANT: Because of the numerous variables which affect sensor readings, the indicated moisture content should not be used as an absolute, quantitative measurement. Sensor readings are, however, very useful guidelines for baling and storing hay.

Understanding the many variables that affect the readings of your tester will help you get the most from your meter.

Field conditions: soil moisture, high or low areas, swales, and shady areas all affect hay moisture within the same field.

Hay varieties: leaf-to-stem ratios, crop maturity, and different cuttings contribute to widely varying moisture distribution in hay plants.

Harvest Variables: bale density, windrow size and shape, time of day, hay temperature, and overall climatic conditions affect moisture readings. High humidity with cloud cover contributes to more variations in moisture readings than a dry, sunny day with a slight breeze.

Some preservatives increase conductivity initially. Until the preservative is absorbed, usually in 1-2 days, it may cause readings to be 2-4 points above the same hay which is untreated.

Bale Density: As the bale becomes tighter in the bale chamber, the moisture readings will appear higher. This is due to the compaction, which varies while the bale is being formed.

Each type of baler feeds hay into its chamber and forms it differently. In general, small, rectangular bales are denser toward the bottom or "light" side; and large rectangular bales are densest in their upper corners.

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Natural variations within the windrow: Non-uniformity is expected in any given windrow. This can occur due to low lying areas in a field and/or drain off channels in the field. The hay that comes in contact with the sensor pad inside the chamber is random. Therefore, pockets of very dry and very wet hay may be detected and those corresponding readings will be displayed.

A poorly prepared windrow can have variations in moisture of up to 20%. Even a well prepared windrow can vary in moisture up to 5%.

Percent of grass in the hay: The tester has been calibrated with 100% alfalfa hay. The more grass in the hay, the higher the moisture readings vs. actual. The following are some guidelines that can be used to adjust readings to compensate for abnormal field conditions:

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