Ask A Farmer: Why do farmers leave dying corn in fields?

Today we have a guest post from Indiana farmer, blogger Brian Scott (Facebook, Twitter). Brian does a great job of explaining difficult questions about farming operations, how crops are grown, and the management decisions surrounding growing Genetically Modified crops. Brian blogs about growing corn, soybeans, and popcorn at

I am always intrigued by the questions people ask about agriculture. What might seem like a silly question to me at first is really a great question from someone who has not been around a farm very much if at all. Apparently, people have been asking Agriculture Proud why farmers let their corn die in the field. I imagine this question is spurred by the idea many people believe when they drive through areas of the country, like Indiana where I farm, they are looking at endless expanses of sweet corn. This is not so.

Farmers leaving dying corn left in fieldThe vast majority of corn spotted in rural America is not sweet corn. And when I say majority I mean like 99% of it is not sweet corn. Not always but more than likely the corn in question is yellow dent corn. Dent corn feeds livestock, fuels cars, and makes plastics, starches, adhesives, and a huge array of other products. Sweet corn is harvested at what would be considered very early in the season for a farmer like me. The plant is still pretty green and the kernels are of course juicy and sweet. I do not want sweet juicy corn on my farm. My corn goes through a juicy stage after pollination although the sugars are more starchy than sweet.

Why let the corn die?

Well to me it’s not dying it’s drying. After pollination kernels appear. Sweet corn is harvested shortly afterward. When the kernels are formed and full of liquid it’s called the milk stage because if you squeeze a kernel the stuff that squirts out has a milky consistency. After milk, we go to dough where the kernel gets a bit more solid. Eventually, we hit black layer, which signifies physiological maturity. Black layer refers to a, you guessed it, a black layer at the tip of the corn kernel. So now, the corn is physiologically mature and dent corn is maybe a month further along than harvested sweet corn. Time for harvest, right? Nope.

Corn drying process

Corn can be safely stored for long periods at 15% moisture. The black layer is around 35% moisture in the kernel. 15% is a level at which the risk for developing storage issues is very low, and it’s no coincidence grain purchasers base their pay schedules on 15% moisture. Higher than that number of corn delivered to the elevator and I have part of my pay taken to cover the elevator’s drying cost. But there’s no premium for delivering under 15% moisture. Fair enough. Not all farmers have dryers on their farms, but many do.

Dryers are generally powered by propane. Our dryer actually looks like a normal grain bin, but the top section has a floor to hold wet grain to be dried in batches. A large burner fan pumps air, sometimes over 200 degrees F, to dry the corn. Traps in the floor open after a specified period of time, and another batch enters.

Why corn needs to dry

So if wet corn costs me money to dry, whether doing it on site or upon delivery, why not leave corn in the field until it dries all the way down to 15% moisture in the field? We tend to start harvest at just over 20% maybe up to 25% normally. We plant various maturities of corn so the drying process is spread out. Sometimes farmers can get a break on drying costs. The local ethanol planted wanted corn early in 2011. In early September, they took corn deliveries for one week while covering the drying cost up to 25%. We harvested about 40 acres near 30% and didn’t harvest anything else until 3 weeks later. Corn starts to be ground up and damaged a bit when it’s that wet running through the combine.

We dry most of our corn ourselves because we have the capacity to store most of our own crop. During harvest, lines at the grain elevator are usually long, and I can’t keep the combine running if there isn’t an empty truck waiting on the roadside. Since corn is in greatest abundance at harvest, the price may be relatively low as well. Storing means we can hold on to grain while waiting for higher prices. Pay or pricing can be held back upon delivery to an elevator as well, but you’ll be charged a per bushel storage fee for the time between delivery and sale.

Farmers leave dead corn in field to dry

Why leave dying corn in fields?

2013 was a wet and cool year overall except for August. Our average harvest moisture was 20% across the whole farm. If we let corn dry all the way to 15% (maybe pushing into December with 2013 weather) in the field we would likely lose more money in grain loss than what we’d pay for drying. I believe this is where the idea of dead corn comes into play. Fields full of browning plants sitting in fields for weeks as compared to green sweet corn. I want the corn to look dried up, but when the time is right, I want the corn out of the field as fast as we can harvest.

The plant is dying and drying right along with the kernels. Stalks become hard and brittle, and ears might start dropping on the ground. Once they hit the ground, my combine isn’t going to pick them up. The last thing I want to see coming at dry corn stalks is a strong windstorm. Wind is bad enough on green and growing corn so it won’t have much trouble knocking down dead corn. The ground also needs to be dry for harvest to limit the risk of soil compaction and for ease of operating equipment.

Now you will know the next time you see acres of green corn that has turned like fall leaves on trees that in the farmer’s eyes his corn is not dying but drying!

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  1. Great explanation (and 99%? I didn’t realize it was that high). A question for you: We spent time in Ontario over the holidays. Somewhere between Barrie and Orillia – with 1-4′ of snow on the ground – we passed a field of unharvested corn. Any thoughts on why that might be? Thank you.

    1. Some people do that for various reasons. Maybe they have a full-time job in town or just operate a little differently. We have some neighbors that always seem to have a few acres cut in January. Sometimes they plant after everyone else is done too!

      1. Isn’t it also true that if the ground is too wet to finish harvesting in the fall, sometimes farmers will wait until the ground freezes to finish getting the crop out of the field?

  2. As a farm wife, it had never occurred to me that folks would think a bunch of sweet corn is dying in the fields! So glad consumers are getting better about asking questions so we can all understand each other better. Great explanation, thanks!

  3. How come after all the hard work of the Farmers part o get moisture content at 15% to sell it, the elevators leave vast piles of corn exposed to the elements for weeks on end? Is this due to the fact those elevators use product for feed meal or ethanol so moisture isn’t an issue? Thanks

    1. Once the corn dries down on the plant, it doesn’t necessarily absorb all the water again when it gets rained on. And yes, sometimes higher moisture may be acceptable depending on the destined use.

    2. Those piles are often aerated with large fans to keep them dry. Most of the time they are also covered with plastic until they need the corn. Once uncovered those piles are often loaded out in short order.

  4. What is done with the stalks after they are “dead looking”, like when the crop is chopped to the ground? Is it used for feed or thrown out or what?

    1. Ryan is correct. Stalks are most often left in the field to decompose. Farmers with livestock may put animals out on the field to graze them, or they might bale them just like you would with hay. In some areas where a cellulosic ethanol plant is near the baled stalks may be turned into fuel. Currently that is not very common nationwide.

      There are many ways to manage the crop residue, and the process starts at harvest. The combine harvester actually is the first thing to process corn stalks, so the way a farmer outfits the combine has an effect of how the residue is left in the field. After harvest the stalks might be worked in with tillage or the field might be no-till. Most farmers don’t do what I would call clean tillage, turning all the residue into the soil with a moldboard plow. More common now is conservation tillage which will pin residue down but not bury it completely. This aids the breakdown process by putting soil microbes in contact with the stalks and keeps wind from blowing residue away. The more residue that is left on the top of the ground the better rain can filter into the soil instead of running off with topsoil in tow. You can imagine a rain drop hitting a corn stalk is less likely to wash away soil that has been tilled heavily, left to absorb the impact on its own.

      Managing crop residue is important because it is not just trash left behind when the grain is gone. Soil nutrients and fertilizer are in those stalks, so the choice to leave them in the field or haul them away for another use has a big effect on future fertility and a farmer must adjust his fertility program accordingly.

  5. My corn is in the dent stage, 1/3- 2/3 milkline at 124 days.It is going to freeze the next 3 days.Should i harvest it or leave.It sprouted June 8.Thanks

    1. Your moisture is probably pretty high yet. Rule of thumb is black layer comes 60 days after pollination. That’s when you reach physiological maturity and dry down really begins. We don’t like to harvest much over 25% moisture. Some people don’t mind 30%, but your going to start grinding and damaging corn in that range and above. I’d let it freeze.

  6. I changed jobs to a rural high school out among the farms and saw the
    drying fields and wondered what was going on—now I know. Thanks
    for the great explanation.

  7. When harvesting corn and your local silos are filled during harvest and the overflow is placed on the ground what is this corn used for? Dose any of the corn stored outside used for human consumption?

    1. That corn will be covered with plastic to keep rain and snow off of it. Aeration fans also keep it in condition just like would happen in a bin or silo. The corn could have any number of uses including human consumption, but the majority of field corn will go towards feeding livestock. There are two piles of corn at the main elevator we go to and once they break that plastic open they usually move the whole pile in short order. They can probably load a train pretty fast.

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