It’s all about uniformity. Plant-to-plant differences reduce yields and it all starts with good seed to soil contact.
Don’t blame Mother Nature for poor corn stands. Weston Wiler believes planting is one variable where the farmer has most of the control.
“Everything you do is important, but that split second you go across that ground planting will define your level of success for the entire year with that crop,” says Wiler, who farms in south central Michigan near Hillsdale.
Wiler’s goal at planting is to establish good seed-to-soil contact. Good seed-to-soil contact and even planting depth contribute to uniform emergence. Farm Journal agronomist Ken Ferrie calls the result of such precision “photocopied plants and ears.”
“Describing corn stands as a picket fence is a way to explain how you did with seed singulation,” says Ferrie. “Planter performance should be precise to give each plant an equal chance.”
To consistently achieve uniform stands, Wiler has slowed his planter down to nearly a walking speed.
“Maybe it takes an extra 20 minutes to plant a field, but what we get in return in ear count makes that additional time trivial,” he says.
Now ear this…Uniform plant stands have a domino effect by contributing to the quality of corn ears.
Later in the season, corn ear numbers are a good indicator of yield potential, because yield is based on the number of ears per acre and the size of the ears (number of rows around, kernels long and kernel depth).
Missy Bauer, Farm Journal associate field agronomist figures 1,000 ears per acre is equal to 5 to 7 bu/acre.
Wiler conducts corn ear counts each August and spends an average of three days per season on the process. Last year, he and four employees did ear counts on every farm he leases.
“We did a spot sample on every farm; we probably checked 100 fields or so,” Wiler says, “We were scouting for weeds and insects at the same time, so while it was a big job, it was pretty efficient.”
The following formula is a tool Bauer says farmers can use top estimate corn yield potential.
Use a tape measure to mark off 17 feet 5 inches in a row of corn planted in 30-inch rows (see chart below).
Count the number of corn plants in the measured-off space. Subtract any corn plants that appear unlikely to produce a good, harvestable ear.
Stalk diameter and plant spacing can help you determine harvestable ears.
“A skinny stalk diameter when compared to neighboring plants, indicates that that particular plant is behind in maturity and will have trouble pollinating or will produce a very small ear and isn’t something we want to count,” Bauer says.
To evaluate plant spacing, Bauer says to look for double drops, which indicates two seeds were metered together by the planter. This situation usually results in two plants that will compete too much for available nutrients, and neither one will end up producing a large, harvestable ear.
Once you determine the number of harvestable ears in the measured-off space, randomly select three to five ears to count rows around and kernels long and use the following formula to arrive at anticipated yields:
Average ears x average rows around x average kernels long = Yield
Bauer inserts some actual ear, row and kernel numbers in the formula as an example.
32 x 16 x 35 = 199 bu/acre
Bauer encourages farmers to implement this practice in four or five different locations within each field, and then average the numbers, to arrive at a fairly accurate, comprehensive result.
“Keep in mind the formula does not take into consideration kernel depth,” she says. “Based on weather conditions during kernel fill you may increase or decrease your yield by 5 to 10 percent.”
As farmers evaluate plant stand numbers and ear counts, Bauer says farmers can benefit from getting those two numbers to more closely align with each other.
“You want to minimize the difference between plant count and ear count numbers,” Bauer says.
For example, she adds: “If you have 30,000 plants/A and your ear count is only 27,000 ears/A, you have the potential to increase yields 15 to 21 bu/A by increasing your ear count to 30,000 ears per acre.”
Bauer says that while the number difference between plant stands and ear counts cannot be eliminated, it can be minimized. She says that in a corn-soybean rotation, the difference between the two would ideally be no more than 1,200. In corn-on-corn, with heavy residue conditions, Bauer says the ideal difference between the two would be 2,000 or less.
Length of row to equal 1/1000th of
an acre for various row widths
13 feet 1 inch
13 feet 6 inches
17 feet 5 inches
23 feet 9 inches
34 feet 10 inches
*Information provided courtesy of University of Minnesota Extension Service.
For more information on the importance of plant uniformity read Iowa State University agronomist Roger Elmore’s column: http://www.extension.iastate.edu/CropNews/2011/0420elmore.htm