How to Measure Moisture Content Using the Microwave

The microwave offers another way to test moisture content. You'll also need:

• A kitchen scale (accurate to 1 gram)
• Scissors
• Paper bag or plate
• Notepad
• Small glass of water
• A calculator (optional)

Instructions

1. Take a representative sample of forage from your swaths and cut into 1/4" to 1/2" (6-12 mm) pieces. Prevent them from drying between collection and initial weighing.
2. Mix sample. Weigh out approximately 100 grams (wet weight), excluding the container weight.
3. Put the sample in paper bag or spread thinly on the paper plate. Place in the microwave along with a glass of water: The water will prevent the sample from catching fire.
4. Microwave on high for 3-4 minutes.
5. Re-weigh the sample and record its weight. Stir to remove hot spots.
6. Place the sample back ii, the microwave and reheat for 1 - 2 minutes. Record the weight and stir the sample again.
7. Repeat Step 6 until the sample loses less than 1 gram between heatings. When this occurs it will be dry (dry weight). A slightly charred sample should not affect the accuracy of the moisture determination. If the sample burns, however, repeat the test.

    When the sample is dry, calculate the moisture content as follows:

    (Wet weight) - (dry weight)    x     100 = moisture content
            wet weight

    For example:
    100 grams - 86 grams    x    100 = 14% moisture
            100 grams

    Instructions as above, but the calculator should be automatic.