An investment of time now can go a long way toward preventing loss of data or downtime during the busy harvest season, says the director of Missouri's Precision Ag Center.

A yield monitor can be one of the most useful tools in a producer's arsenal, provided it is in good running condition and properly calibrated said a University of Missouri Extension agricultural engineer.

Kent Shannon, associate director of the Missouri Precision Agriculture Center (MPAC), said about 500 producers in the state use some type of precision agriculture, and a significant number of them have yield monitors. Some of those yield monitors are equipped with Global Positioning Systems (GPS), which allow farmers to make maps showing the distribution of yields in their fields.

Shannon provided a checklist for farmers with yield monitors. Before going into the field, he said producers should take the following steps:

1. Visually inspect all sensors and cables. "It's much easier to make repairs now than during harvest."
2. Moisture sensors that are mounted in the grain tank auger should be inspected for wear or damage. Auger flighting should be checked, too. "If you have an elevator-mounted moisture sensor unit, make sure the manual clean-out switch engages the motor." And check that the moisture sensor is properly grounded.
3. Inspect the grain flow sensor for wear. Also check the clean-grain elevator for wear, missing or worn paddles and loose chains. Clearance between the paddles and the top of the elevator should be between 3/8 and 5/8 inch or 3/8 and 1 inch, depending on monitor.
4. "With your combine in an open area, power up your GPS receiver and make sure you're receiving a good differential correction signal." Also check communication between the GPS and the monitor.
5. Raise and lower the header to make sure data is recorded only when the header is lowered, not when it is raised.
6. Engage the separator and observe elevator speed. "Put the combine in gear and drive forward to see if the ground-speed indicator is working." Once in the field, Shannon said, the farmer should begin by calibrating the temperature sensor if the yield monitor is an Ag Leader or a Case IH AFS. "Calibrating the grain flow sensor is the most important step in calibration of your yield monitor," he said. Calibration loads should be at least 4,000 pounds. "Begin with combine and weigh wagon or truck completely empty and end with the combine completely empty and all grain in the weigh wagon or truck."
7. Check that data collection cards (SRAM or ATA Flash) are working properly and formatted.

Shannon said Ag Leader and Case IH AFS monitors require the farmer to calibrate the grain flow sensor using multiple grain flow rates to determine a calibration curve for a range of yield levels. "A range of grain flow conditions can be achieved by simply driving the combine faster or slower than normal," he said, adding that another approach is to harvest using only one-fourth to one-half the normal cutting width while traveling at normal speed. In other yield monitors, the grain flow sensor may be calibrated with one load of grain harvested under normal, expected harvest conditions. "Determining a zero reading when no grain is being harvested completes the calibration," he said.

Set the swath width properly, Shannon said. "In non-row crops, set the monitor swath 1 foot less than the platform width." Remember to log in the correct crop type for all fields, and before using the yield data, weigh at least six separate loads for initial calibration or to recheck calibration after a period of use.

"Calibration of your yield monitor should be repeated or checked if major differences in harvest conditions are encountered," he said. Manufacturers recommend recalibration if differences across hybrids exceed 5 percent in grain moisture, 5 pounds per bushel test weight or a variation of more than 15 degrees Fahrenheit in grain temperature.