How many Growing Degree Days have we Accumulated?

May 12, 2021
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By:  Stephanie Karhoff

Spring began with spurts of unseasonable warmth in April followed by a cool, wet period this past week.

In April, 188 growing degree days (GDD) were accumulated in Bryan. The 30-year average of GDD accumulated for  April is 167. Mother Nature, however, turned off the heat. We gained only 60 GDD from May 1-10, compared to the 30-year average of 111 GDD.

What does this mean for corn emergence? According to the Ohio Agronomy Guide, it takes 100 GDD’s for corn to emerge. In Bryan, corn planted on April 27th would have acquired 100 GDD’s by May 9th. Keep in mind, rate of emergence may be influenced by other factors besides soil temperature. These include planting date, soil moisture, soil residue, seeding depth, and more (https://cropwatch.unl.edu/growing-degree-units-and-corn-emergence).

You can estimate corn emergence using the GDD calculator found at https://mrcc.illinois.edu/U2U/gdd/. To use the tool, find your location on the map and then select the “GDD Start” (a.k.a. actual/anticipated planting date). The graph will display accumulated GDD’s for your location. Example output below shows GDD accumulation from an April 27, 2021 planting date near Bryan.

Example of output from https://mrcc.illinois.edu/U2U/gdd/

References

Thomison, P., Michel, A., Tilmon, K., Culman, S., and Paul, P. 2017. Chapter 4: Corn production. Bulletin 472 – Ohio Agronomy Guide, 15th Ed. Pages 32-55.

Lindsey, A. and LaBarge, G. 2021. Growing Degree Days vs. Calendar Days – How Long Will Emergence Take? C.O.R.N. Newsletter. 13-2021. https://agcrops.osu.edu/newsletter/corn-newsletter/13-2021/growing-degree-days-vs-calendar-days-%E2%80%93-how-long-will-emergence

Elmore, R. and Mueller, N. 2015. Growing Degree Units and Corn Emergence. University of Nebraska-Lincoln Institute of Agriculture and Natural Resources CropWatch. https://cropwatch.unl.edu/growing-degree-units-and-corn-emergence