Corn yield
181 to 236bu/acre
- At 30-inch rows, measure 17 ft 5 in of row. That is 1/1000 of an acre.
- 30 ears × 512 kernels an ear = 15,360 kernels in that row.
- That is about 181 to 236 bushels an acre, using Purdue's kernel factors of 65 to 85.
- Purdue says this is good to about 20 bushels either way. Count in 5 or more spots and average them.
Row length for 1/1000 acre
| Row spacing | Row to measure |
|---|---|
| 7.5 inches | 69 ft 8 in |
| 15 inches | 34 ft 10 in |
| 20 inches | 26 ft 2 in |
| 22 inches | 23 ft 9 in |
| 30 inches | 17 ft 5 in |
| 36 inches | 14 ft 6 in |
| 38 inches | 13 ft 9 in |
43,560 ÷ row spacing in feet ÷ 1,000, from Purdue. Ohio State gives the same lengths for soybeans.
How to count corn, Purdue's way
- Measure the row length for your spacing.
- Count the ears you will harvest in it.
- On every 5th ear, count the kernel rows and the kernels in one row. Skip the odd kernels at the butt and tip.
- Multiply rows × kernels for each ear, and average them.
- Ears × kernels an ear ÷ 65, 75 or 85 gives bushels an acre.
Purdue's example: 30 ears of 511 kernels gives 236, 204 or 180 bushels an acre.
Questions
How do I estimate corn yield?
Count the ears in 1/1000 of an acre. Count the kernels on some ears. Multiply ears by kernels an ear, then divide by 65, 75 and 85. That gives a low, middle and high yield, says Purdue.
How long is 1/1000 of an acre?
Divide 43,560 by your row spacing in feet, then by 1,000. For 30-inch rows it is 17.4 feet. For 15-inch rows, 34 feet 10 inches.
How accurate is it?
Purdue says the corn method is good to about 20 bushels an acre either way. Count in several spots in the field and average them.
Why divide by a bigger number in a dry year?
The factor stands for kernel weight. Small, light kernels mean more kernels in a bushel. Purdue uses 90 to 100 for a stressed crop.
How do I estimate soybean yield?
Count plants in 1/1000 of an acre and pods on some plants. Multiply plants × pods × seeds a pod. Divide by seeds a pound × 0.06. Ohio State uses 2.5 seeds a pod and 3,000 seeds a pound.
Sources
- Purdue University (Nielsen), Estimating Corn Grain Yield Prior to HarvestAug 2021The corn method: ears, kernels and the kernel weight factor; row length for 1/1000 acre
- Ohio State University C.O.R.N. Newsletter, Estimating Soybean Yield2018The soybean method: plants, pods, seeds per pod and seed size