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Department of Crop Sciences
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Estimating Corn Yield
Making plans for storing and marketing the crop often calls for estimating yields before the corn is harvested. Such estimates are easier to make for corn than for most other crops because the number of plants or ears per acre can be counted fairly accurately.
Estimating corn yields is done by counting the number of ears per acre and the number of kernels per ear, then multiplying these two numbers to get an estimate of the number of kernels per acre. Next, simply divide by an average number of kernels in a normal bushel to get the yield in bushels per acre.
Corn yields can be estimated after the kernel number is fixed - about 2 weeks after the end of pollination. The following steps are suggested:
1. Walk out in the field a predetermined number of rows and paces. For example, go 25 rows from the edge of the field and 85 paces from the end of the field. If this pattern is not determined beforehand, there is a tendency to stop where the crop looks better than average. Stop exactly where planned.
2. Measure 1/1,000 of an acre (Table 2.05), and count the number of ears (not stalks) in that distance. Do not count ears with only a few scattered kernels.
Table 2.05. Row Length Required to Equal 1/1,000 Acre
Row width:
20"
28"
30"
32"
36"
38"
40"
3. Take three ears from the row that was counted. To avoid taking only good ears, take the third, sixth, and tenth ears in the length of row. Do not take ears with so few kernels that they were not included in the ear count.
4. Estimate the kernels per bushel
Select the approximate number of kernels per bushel:
(90000 is an average approximate value based on corn grown in normal conditions. Factors such as excellent growing conditions - larger kernels - or dryness, insects or disease - smaller kernels - can have an effect on this number)
This value can be corrected by either using the following buttons to select a kernel size, or by manually typing in a new value.
Larger kernels (smaller count)
Smaller kernels (larger count)
5. Count the number of rows of kernels and the number of kernels per row on each ear. Enter these numbers in the following table to calculate the average kernel count per ear for a sample of three ears. Enter up to five samples of three ears into this table. The average yield will automatically be calculated when you enter a sample
Sample #
Ear #
Rows of kernels
Kernels per row
Ears per 1/1000
acre for sample:
Average
Kernel Count
Average
Yield / Sample
1
1
2
3
2
1
2
3
3
1
2
3
4
1
2
3
5
1
2
3
Average yield for field:
bu/acre # of samples:
6. To get a reliable average, use at least one sample for every 5 acres in a field.
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