When checking moisture of binned grain, use a six foot or 10 foot probe to collect samples from various depths. Go as deep as possible at bin center and several other locations. Do not mix the samples. Knowing moisture content at different locations can help you find the drying front in drying bins or trouble spots in storage bins. If you don't have a probe, take the samples at arm's length below the surface.
Crusted grain can cave in unexpectedly.
Never enter a bin that is being filled or emptied. Wear a dust-mist respirator, especially if any spoilage is evident. If you are using a portable moisture tester, first make sure the battery is charged. A low battery can cause inaccurate readings. The battery should be removed during the tester's long, idle periods to prevent damage from leakage, and replaced at least once per year.