Estimating Corn Yield before Harvest

Predicting corn yield before harvest is popular with growers, but these estimates can be misleading. It is important to be careful when calculating estimated yields. You must determine the number of ears in 1/1,000 of an acre, average kernels per row, average rows per ear, and average value for seed weight based on the growing conditions.

Counting Harvestable Ears

Yield estimate accuracy increases with more sites tested. Yield estimates should be determined from at least five—and preferably ten—sites within a field. Field data collection is based on a 1/1,000-acre area. Table 1 gives row length needed to equal a 1/1,000-acre area for popular corn row widths. It is likely that actual yield will be 10 percent higher or lower than the estimated yield because of variation in plant uniformity, health, and height, and soil moisture levels in a field.

Yield Estimate Equation

• Step 1. Count the number of harvestable ears in the length of row equivalent to 1/1,000 of an acre. For 30-inch rows, this will equal 17 feet 5 inches.
• Step 2. Count the number of kernel rows and kernels per row on every fifth ear, and determine an average for each yield component. Do not count small kernels located on the butt or ear tip. If variability in crop development exists within a given field, increase the sample size for better yield estimates.
• Step 3. To determine the yield, transfer the values from steps 1 and 2, rounded to the nearest number, to Table 2, 3, or 4 depending on the current year’s growing conditions.

Example

30 ears in 1/1,000 of an acre

14 kernel rows per ear

30 kernels per row

In a good irrigated corn field with no stress from pollination to physiological maturity, use Table 2 to find the yield estimate is 164 bushels per acre. If your growing conditions were evaluated as extreme stress in dryland corn from pollination to physiological maturity, use Table 4 to find the yield estimate is 113 bushels per acre.

Publication 3935 (POD-08-23)

Revised by Bill Burdine, PhD, Extension Specialist, North Mississippi Research and Extension Center, from the original by Dennis Reginelli, former Regional Extension Specialist for Agronomic Crops.