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Corn Yield Article An exclusive pre-season report by AgWeb.com editors to help corn growers maximize their results in a year when every move counts.
Ken Ferrie, Farm Journal field agronomist, has spent the past 16 years in Midwest corn fields trying to document exactly what happens in the field from the time the seed goes in the planter box to when it hits the grain auger the following fall. Ferrie is still looking for the perfect stand of corn, believing that a lot of yield potential is lost even before the emerging crop is a foot tall. At this year's National Farm Machinery Show in Louisville, Kentucky, he shared his field observations with growers. His central message: Corn yield is determined much earlier than most farmers realize. Ferrie refers to the vegetative development stages of the young corn seedling, such as V-1, when the first collar can be seen. "By the 4th. leaf collar, the plant is thinking about yield; yield potential is determined at the 5th to 6th leaf collar stage. Keep in mind that these nodes are being pushed skyward as the plant develops additional nodes lower. That means counting from the top of the plant down, the plant wants to set its yield at the 6th or 7th. node down from the tassel. That's where the greatest yield potential can be set. You may still have 400 bushel yield potential." Ferrie continues, "But, put the plant into any kind of stress during germination and emergence, and it will then decide to select the 8-9 node, and your yield potential has dropped to 300 bushels per acre. All pre-determined by stress at germination!" Watching the young seedling, Ferrie puts great importance on what happens at the 5-collar stage. "It is at that point in development when the maximum number of kernels around an ear are determined. This is when the plant decides whether to set 22 kernels around; 18; 14-whatever. This is where early stress will be exhibited in the final ear. Fifth collar.," Ferrie states. Now, with the plant about 8 to 10 inches tall, and at the 6th collar, "that is when the maximum ear length is determined," Ferrie explains. "That will be re-negotiated at the V11-12 stage, in mid-season." From what Ferrie has seen going on in corn fields the past 16 years, he is inclined to conclude, "You may very well be stuck with your yield at the V-6 to V-7 stage. That surprises most farmers when I tell them that. They think yield comes in July and August. No. Much earlier." Ferrie tell farmers what he is looking for is "picket fence stands and photocopy ears." He has not seen the perfect field yet. By picket fence stands he means consistent seed and plant placement with equidistant spacing. Any skips or doubles detract from yield potential. Similarly, he is looking for identical ears, both in the number of kernels around and uniform ear length. Barren plants are weeds! He explains why the germination period is so critical. "All corn seeds must germinate uniformly within a 24-48 hour window. Seeds which germinate outside of that window will not have a chance because that seed's siblings are already not compatible with that late starter. They will see that tardy corn plant as a "weed" and competitor," Ferrie tells his winter audiences. "Odds are very high that tardy seedling may not even produce an ear! It will soak up sunlight, nutrients and water, and then be barren. All because of getting out of the gate late, compared to the other seeds." To reinforce the point, he explains, "If a corn plant falls one-collar behind all of the neighboring plants, it will not put on an ear." And, if there are many plants without ear potential, "you just as well have 5,000 rag weeds per acre. That's all those corn plants are-rag weeds." Based on experience, the crop consultant now thinks ear count is very predictive when plants are 6 to 8 inches tall. "At that point, I can flag skips and doubles and late comers, and note that what was a 32,000 planted population through the planter may only be 24,000 plants per acre with the potential to make an ear. You may already be down to no more than 150 to 160 bushel yield potential-with the plants barely 6 to 8 inches tall." This is shocking new information for most corn growers! At that small plant size, growers find it hard to believe their crop is already 40-50 bushels off the pace. At this young stage, they may be confusing green plants with eventual ears. Such will not be true. "Ears make yield; not plants." But Ferrie jokes with growers, "I know, at that early stage, you are just glad that it is up and green and growing!" There is another downside to plants which encountered early stress and are not putting their energy into producing an ear. Instead of sugar going into the formation of an ear, the sugar is loading up in the plant, making it a very tasty host plant for corn borer larvae. The barren plants can make a very cozy safe haven for corn borer infestations, with resulting stalk damage to complicate harvest later on. Ferrie puts a great importance on planter accuracy. In fact, it is his recommendation that a grower allocate three hours per planter row, just getting it ready to go to the field. Three hours per row to make sure every part is performing perfectly. "At 7 mph (too fast in Ferrie's opinion) in 30-inch rows, your seed drop is 17.6 seeds per second." That leaves a lot of room for error, as he has seen year after year. The corn doctor says, "There is nothing you can do to fix a stand after it comes out of the ground." He advises growers to have whatever equipment it takes to get the farm's entire corn acreage planted in five working days. He sees too many farmers hurrying to get planted; driving too fast for accurate seed placement. "That is probably the biggest single problem working against picket fence stands." Planter calibration is also a big issue. A recent AgWeb.com Question of the Week drew these responses: 28% were using a third-party professional to help them calibrate their planter; 32% said they calibrate their own planter ahead of planting; 26% said they make calibration adjustments once they are in the field; and another 13% said they trust the planter set-up and normally do not calibrate. Ken Ferrie thinks high yields start with a well-tuned corn planter. "It should be running like a sewing machine." Then he pokes his audience: "Too many times, I see a shiny pickup truck in the garage and the corn planter sitting in a grove of trees. I would suggest you get the planter into the garage, and leave the truck in the wood lot. Get your priorities straight, guys!" |
That bag of seed corn sitting on your truck tailgate has the genetic potential of producing 400 bushels of corn per acre. But, by the end of the growing season, you may be lucky to harvest 160 bushels per acre. So, what happens along the way?