Estimating Corn Yield

Early corn yield estimations are a great way to get out into your field and start to predict the yield of different varieties given the growing season. It allows a grower to start making harvest decisions, marketing decisions, and to estimate needed storage capacity.

How many spots should I sample from?

Generally doing a kernel count every 10-15 acres is recommended. For soils that are extremely variable, doing a kernel count every 5-10 acres would be beneficial. Select random spots in the field when walking through as you are trying to get the best representation of the field.

Steps to take for estimating corn yield

  1. Measure 1/1000th of an Acre. Measure the length stated against one row of corn.
Row width1/1000th of an acre
20″26′ 1″
30″17′ 5″
36″14′ 6″
38″13′ 10″

  • Count the number of ears in the row length that you measured.
  • Select 5 average cobs in the measured length. Count the number of rows around the cob and then multiply that by the amount of kernels in one of the rows. Only count the kernels that are fully developed, and not aborted kernels.
  • Repeat this for every spot, recording your results each time.
  • Calculate the average for the number of cobs per row and kernel count for all the sample areas.
  • Determine your kernels per acre using this formula:
    Average number of ears x Average number of kernels x 1000
  • The last step will be to figure out how many kernels are in a bushel. The number commonly used in Ontario is 90,000 kernels per bushel. This may differ depending on your variety. Take your answer from Step#6 and divide it by either 70 000, 90 000, 110 000 depending on your seed size. This is your bushel per acre estimate.

    Calculating Corn Yield Chart

    Representative kernel sizes to help guide you in determining the kernels per bushel for different varieties.

  • Things to remember

    • Yield estimates are only as accurate as the samples that you take. Make sure you sample several areas over the whole field.
    • The best estimates are taken as close to black layer (physiological maturity) as possible.
    • Insects, disease and water can all affect actual final yield from the time you take your estimate to the time you harvest.

    Contact us

    For more information contact one of our Agronomy Solution Specialists or any local Thompsons branch.

    Chris Hunt, CCA
    Agronomy Solutions Specialist
    Phone: 519-676-5411, Ext. 20478 | Cell: 519-365-3593

    Jevin Vyn
    Agronomy Solutions Specialist
    Phone: 519-676-5411, Ext. 20303 | Cell: 519-401-2120

    Mike Wilson
    Advanced Agronomy Solutions Manager
    Phone: 519-676-5411, Ext. 20480 | Cell: 519-809-0284

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