Why is it important to test hay moisture Prior to Baling? Proper moisture levels during baling are essential to produce better quality hay and reduce economic losses. Baling hay at the correct moisture levels reduces mold development and helps to preserve the color and feed value of the hay. Testing the moisture content of hay prior to the baling process is essential to both seller and buyer. Moisture in hay is considered in three different forms, free water, physically trapped water, and bound water. The free and physically trapped water can be evaporated given proper conditions that include solar radiation, relative humidity, and time.