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NC State Extension

Guidelines for Estimating Yield for Corn

Dr. Ron Heiniger

Determining the Yield Potential

The following procedures are used by the federal crop insurance adjusters and can be used to assess potential yield in corn. This assessment should be done in late dent stage.

Step 1: Determine the Stage of Growth

Mark off a section of row representing 1/1000th of an acre. Table 2 shows the row length required for several different row spacings. Within this section, harvest the ears. You could count them and multiply by 1000 and obtain the harvest plant population.

Step 2: Determine or Estimate the Weight of the Grain on Each Ear

There are two ways of determining grain weight per ear. The most accurate is to weigh the ears as a group and then multiply by 850. This will give you a conservative estimate of grain weight per acre. Another method is to estimate grain weight based on ear length. An ear that is 4 to 6” in length should produce 1/4 lb. of grain. A 6 to 8” ear should produce 1/3 lb. of grain. An 8 to 12” ear should produce 1/2 lb. of grain. (remember to use the average size not the largest or smallest) In this case, take the number of ears times the estimated grain weight per ear times 1000.

Step 3: Determine Crop Yield Potential

Once you have determined grain weight per acre from the steps above, the final step is to divide by 56 (lbs/bu) and you have the yield per acre. Table 2. Row length needed to measure 1/1000th of an acre for determining plant populations at different row spacings.

Row Spacing (inches) Length for determining
1/1000th of an acre (feet).
20 26.1
24 21.8
28 18.7
30 17.4
36 14.5
38 13.8
40 13.1