For smaller farms, moisture testing procedures using standard kitchen appliances have been developed. Although they are not as accurate as laboratory or electronic tests, they do give the farmer useful information.
According to the University of Manitoba, testing the moisture content of hay can be accomplished with a home microwave.
The farmer should select a representative sample and cut the hay into one-quarter to one-half inch pieces. Weigh out 100 grams of the hay sample with a kitchen scale. Other weights can be used, but 100 grams will simplify the math of calculating the moisture content.
The sample is placed on a paper plate and microwave for three to four minutes, along with a small glass of water to prevent fire in the microwave. At the end of the cycle, remove and weigh the hay before returning it to the microwave for one more minute.
The weight loss of the hay represents the moisture evaporated out of the hay. The microwaving and weighing cycle is repeated until the weight remains constant from cycle to cycle. This indicates all the moisture has been removed from the hay. At this point, if the process started with 100 grams of hay, the difference in the weight between the dried hay and 100 grams is the percentage moisture content of the original hay.
If the testing started with something other than 100 grams of hay, the formula for determining the moisture content is the original weight minus the final weight divided by the original weight times 100.
The best time to moisture test hay is just before baling or loose stacking is planned. The idea is to determine if the hay is at the right moisture content for storage before it is baled.
Also, caution is suggested during microwaving to make sure the hay doesn't burn. The fire could damage the microwave, and the smell of burnt hay is likely to linger for a long time.