Your yield monitor can build a road map to higher yields or it can be an expensive cab ornament, producing about as much useful information as a TV sitcom. The difference hinges on understanding a handful of basic facts about monitors.
Assuming you own a monitor capable of creating a good yield map, calibration is critical. "If you don't do a good job of calibration, a yield monitor is kind of useless,” says Dennis Noland, Blue Mound, Ill., farmer. "Your yield map may be pretty, but the picture won't tell you much. With a good map, you'll have clear spatial definition. You'll see that yields line up with factors like soil type and drainage.”
Sharp definition lets you define management zones—which lets you start taking advantage of variable-rate technology, leading to more efficient use of inputs and higher yields. You can overlay your yield maps with other tools like a Normalized Difference Vegetation Index (NDVI) images for even greater precision.
Not all yield monitors are created equal. Some can do a good job of recording total bushels but not as good a job of building spatially accurate yield maps required for precision agriculture.
Here are several principles, courtesy of Farm Journal Field Agronomist Ken Ferrie, you must understand.
The road to accuracy starts with pre-season maintenance. Inspect your clean grain elevator chain and the pressure plate of your monitor, where yield sensing takes place. "Check the clearance between the paddle and the pressure plate,” Ferrie advises. "Pull the pressure sensor out, and check the plate for wear. If it is thin, it might need to be replaced.”
"Check the tightness of the clean grain elevator chain,” Ferrie continues. "If the chain is too loose, it could hit the pressure plate. Also look at the paddles; if a rivet comes out, the paddle can hit the pressure plate.”
Turn the machine on, and make sure the monitor is working. Rodents may have chewed through a wire.
Now that everything is working, clear out last year's data. Enter any new field names or numbers. That will help you keep information labeled and organized when you go to the field—and it is easier to do at your desk.
Decide in advance where you're going to calibrate. "A very important part of calibration is finding the right spot to do it,” Ferrie says. "You need an area in a field that yields uniformly because you are going to simulate different yield levels by varying the combine speed. Look for a spot where the yield is uniform and you can harvest 4,000 lb. to 6,000 lb. of grain. Avoid wet spots and hills.”
You can do this planning well before harvest season. "Use past yield maps to find areas where yield has been consistently uniform from year to year,” Ferrie says. "Pick uniform areas in as many fields as possible.
If it's your first season to use a yield monitor, recall past yields and field scouting to find a calibration area. You may need to put in a headland with your combine, in the middle of the field, to get to a uniform section.
- Summer 08