Harvesting corn at the proper moisture content is critical for making good silage. Corn should be 60-65% moisture (35-40% dry matter) when chopped for silage. The percent moisture can be
determined on-farm with a few basic tools: a microwave, kitchen scale that measures ounces or grams, microwavable container, microwaveable glass and garden shears.
Begin by collecting at least three samples from different locations in the field. If possible, collect the samples from a wagon load of chopped corn. If that is not an option, cut plants by hand at the same height they will be mechanically harvested. Selecting a representative sample of standing corn is challenging, but it is important to get a good sample. The results you get are only as good as the sample you collect. Next, chop the plants into thumbnail size pieces using a garden shears. Stir the chopped material to mix and select a grab sample of approximately 10 ounces.
Weigh the sample and place it in a microwaveable container. Keep a glass of water three-fourths full in the back corner of the microwave while drying the sample. Microwave the chopped sample on 80-90% power for no more than five minutes. If the corn feels dry, weigh the sample. If it is not dry, continue to microwave in 30-second intervals, weighing the sample each time until the weight does not change. If the material chars, use the last weight for the calculations.
Calculate the percent moisture by taking the wet weight minus dry weight then divide that number by the wet weight. Subtract the percent moisture from 100 to determine percent dry matter.
For more information contact Valerie Tate, field specialist in agronomy for the University of Missouri Extension by email at email@example.com or by phone at 660-895-5123. MU Extension programs are open to all.