One of my favorite radio commentators is Paul Harvey. He's the guy who can say "page two" with so much conviction that nobody in their right mind would turn off the radio before he's done reading page two. He also has a radio program called "The Rest of the Story". Sometimes words are written or said regarding a particular topic without us ever getting the rest of the story. Such is the case regarding a four-year research study at Purdue University reporting that corn grain loses up to 1 percent dry matter yield per point of moisture loss as it drys in the field from 28 to 18 percent kernel moisture. This would amount to 10 to 15 bushels per acre in most Wisconsin corn fields.
Several national farm publications picked-up on this study and gave it prominent coverage. The "mystery" yield loss, as one coined it, is reportedly the result of respiration occurring in the kernel during the dry-down period. One article even featured a farm operation that had invested in a new high-speed dryer to handle corn harvested at 26-28 percent moisture in an effort to avoid the field respiration losses.
Now it's time for "The Rest of the Story." At least six additional research trials in the Midwest by other universities and private seed companies have not been able to duplicate the results reported in the Purdue study. In other words, there was little or no loss in kernel dry matter (yield) from respiration as corn dried in the field.
Further studies examining respiration losses for harvested wet corn in storage at several moisture levels indicate that a 1 percent yield reduction per point of moisture loss would be very unlikely. Most of these trials were done at temperatures of 75 to 86 degrees F where it took ten days to see a 1 percent dry matter loss from respiration. In field conditions, temperatures would be about 50 to 60 degrees F resulting in significantly slower respiration rates.
Another potential problem with harvesting corn at high moisture levels, drying it down, and cooling it rapidly, is the negative impact on grain quality. This type of system results in grain with severe stress cracking and susceptibility to breakage or mold infections.
Determining the optimum time to harvest corn for maximum yields is not an easy decision, especially in a year like 1996. However, the condition of the crop, not moisture, is clearly the most important factor. The ability to get fall tillage work done must also be factored into the equation.
Where stalk lodging problems are evident, a producer has no choice but to harvest the grain at higher than normal moisture levels to avoid significant yield losses. This may be the case in many 1996 corn fields where poor root development, ineffective rootworm control, and European corn borer damage are contributing to severe plant lodging.
In fields where plant lodging or ear loss is not evident, most economic studies point to maximum profits by letting Mother Nature do the lion's share of kernel dry-down work. Keep in mind that relatively little moisture loss will occur through the months of November and December.
For more information contact Mike Rankin|
|