Waiting on improved harvest weather? Make sure your combine's ready
Does the wet weather have your combine parked? The delays in harvest thus far in the Corn Belt are adding a greater premium to those dry days when you will be able to get the wheels turning again.
But, once the weather dries up, don't get in such a hurry that you lose bushels because your machine's not properly adjusted, says Iowa State University ag and biosystems engineer Mark Hanna. Taking the time to make sure your combine is ready for the conditions you'll face in the field will pay off.
"In average-to-good crop conditions when the crop is standing well, field losses attributable to the combine should be one bushel per acre or less. Two corn kernels or 4 soybeans on the ground per square foot equals one bushel per acre loss," he says. "Larger areas should be checked for dropped ears as a single dropped ear represents several hundred kernels. One three-fourth pound whole ear per one-hundredth acre (436 square feet) equals a one bushel per acre loss."
The first step to avoid such losses doesn't start with the combine; rather, look first to the landscape itself, Hanna advises. Make sure you get a good idea of the field conditions you'll face when you roll the combine into the field. If you already did that before rains began to fall, however, you might want to do it again.
"Everone, regardless of field conditions, should take time to check field losses this fall and make appropriate combine adjustments," Hanna says. "Gullies and rills may have been created by intense late summer rainfall and hail-damaged areas. Areas affected by adverse weather should be scouted before harvest for the size and condition of ears as well as gullies or holes that may have formed. Fields with wetter corn may have delayed harvest; scout and consider stalk strength before making the decision to delay."
Once you know what kind of conditions you'll be running the combine over, turn your attention to the iron. While it all starts with your machine's owner's manual, Hanna advises these steps:
- Start with rotor/cylinder speed at the lower end of acceptable range, then increase speed only as required to keep threshing losses acceptable
- Concave clearance should start near the wider end of the range, then be adjusted narrower only enough for acceptable threshing and material flow (Plants that have been hail-damaged are more likely to have grain that is brittle and susceptible to breakage if threshing is not gentle).
- In the cleaning shoe, begin with suggested sieve settings and start with fan speed near the higher end of the acceptable range. The objective of fan airflow is to fluidize the material mat on the sieves. Fan speed should be lowered only enough to avoid grain loss. If corn is lighter test weight due to hail or other field conditions, fan speed will need to be reduced somewhat to avoid significant grain being blown from the combine.
- Knife sections should be sharp and in register, and flexible cutterbar and header height control in good working order. These adjustments will have even more importance if soybeans are lodged or many low-hanging pods are present. A second, lower hanging ear seems to be more prevalent in some corn fields this year. If harvestable grain is present on the lower ear, adjust cornhead height appropriately.
- The gap between deck plates above snapping rolls should be adjusted narrow enough to avoid shelling of butt kernels on snapping rolls, but wide enough to avoid excessive stalk breakage. A one and one-fourth inch gap is typical, but this gap should be adjusted as necessary for field conditions.