As hard as it is to believe, corn harvest season is upon us. What are a few important topics we should be addressing during combining season?
A couple of the questions I normally get in the fall are 1) How wet should my corn be at harvest? And 2) How can I minimize header loss?
Although it is hard to know what moisture we’ll be dealing with this fall as I sit down to write, we normally have two extremes that drive the question: too wet or too dry.
The ‘too wet’ situation is a harvest timing and storage issue; too dry is more of a harvesting issue. My ideal range is 17-23 percent moisture for harvesting corn. This range is something to shoot for but could be expanded with acreage constraints, timing, or storage needs.
Why is 23 percent my high end of the range? It is the point where grain can be safely stored in a natural air bin over winter without the chance of the kernels freezing together. Many new corn producers in the Red River Valley region rely on this type of drying. It is a nice way to harvest grain quickly and normally leads to good grain quality when dry.
Corn in the upper 20s has a chance for greater mechanical damage as well, leading to reduced storage time and chances for lower test weights.
Corn that is too dry at harvest can be an issue, as well, which is what we’ve encountered more often in recent years. Gathering loss includes ears missed or lost by the machine, kernels shelled and lost by the stalk rolls or cornhead, which is where most harvest loss occurs.
Threshing/separating losses are found behind the machine. Threshing losses are from kernels not properly shelled from the ear while separating losses occur from kernels that are not separated from the cobs, husks, or leaves.
Speed is key in reducing header loss with dry corn. Ground speed needs to be in a good ratio to roller speed. Plants should be pulled straight down through the header. If plants are leaning forward before being pulled down, the ground speed is too fast. Stalks that violently fly through the header indicate that ground speed is too slow in relation to roller speed.
Deck plate adjustment is also very important. Spacing that is too wide will lead to butt shelling of the ear. Spacing that is too narrow will lead to higher than normal leaves and stalks, which makes it harder for the combine to separate the grain from the trash.
The plates should be set to 1/8” bigger than the average stalk size for the field. On-the-go adjustments have made this easier but it’s important to check for wear and spacing before you begin. I suggest checking for harvest loss periodically throughout harvest, not just in the beginning. Just two kernels per one square foot is nearly equal to 1 bu/A of lost corn.
We want to harvest and sell every kernel we produce. Proper maintenance and adjustments during harvest are critical in achieving this. Typical drying rates in the field are not very high and normally will not change too much. Don’t wait too long and give up good harvesting days to try and save a couple points.