Each year at planting time, we have the opportunity to set the tone for the entire growing season. Seedling establishment is crucial to the success of the crop. Rapid and consistent emergence will determine the yields that are harvested in the fall. With a perfectly even stand, each corn plant has the best opportunity to produce complete ears and reach full yield potential. When uneven emergence occurs early, emerged plants have a head start both in size and nutrient availability. As the crop begins to canopy, the later emerged plants become shaded out and capture less sunlight.
Having an evenly established corn crop is attributed to seedbed preparation, soil moisture and temperature, and consistent planting depth. If any of these three items are not done correctly, plants will emerge at varying times, and yield potential will suffer. 100% of the final stand should be emerged within 24 hours of the first plant breaking through the soil. Plants that emerge more than 24 hours behind their neighboring plants will not be able to catch up in size and will produce smaller ears. In 2019 we were able to record a 9 – 10 bushel difference in plants emerged after the 24 hour window, roughly a $30-$35 loss in gross income per acre.
An easy way to track emergence and calculate the yield loss due to uneven emergence is with a flag test. Mark off 1/1000th of an acre (30inch rows, 17 ft. 5 in.) in a well-representative portion of your field. You will need colored flags to help you keep track of your seedlings. Every morning check the field and mark each plant that emerges with one color of flags. Each day use a different color of flags to mark the plants that emerged. Once all the plants have been flagged and emerged, you can track how each plant progresses through the growing season. At the end of the season pull all the ears from the flagged plants and calculate both kernel counts and ear weights. Average together the weights for each day and track the yield difference from the first emerged plant to the last. The results from a flag test Champion Seed performed in 2019 are on the right.