Mid-Michigan soil temperature conditions in relation to corn seed germination
Corn planting when soil temperature and moisture conditions are most favorable is critical to uniform emergence and stand establishment.
Soil temperature along with soil moisture conditions determine the ideal planting time for many Michigan crops. The minimum threshold temperature for corn seed germination is roughly 50 degrees Fahrenheit in the seed zone (purple/straight line in the two figures below). When the minimum soil temperature (at a 2-inch depth) drops much below 50 F for an extended period of time, there is potential for chilling injury and delayed germination. Under ideal soil temperature and moisture conditions, corn will emerge in seven to 10 days.
A quick check of the soil temperature data since April 1, 2017, at a 2-inch depth from Michigan State University’s Charlotte Enviro-weather station (Eaton County) and Leslie Enviro-weather station (Ingham County) shows the minimum soil temperatures during the past seven days have been fluctuating above 50 F. The maximum soil temperature has consistently reached above 50 F during the same period. The average soil temperature has also stayed above 50 F. Typically, soil takes a longer time to warm up than air, but fluctuations in soil temperatures do occur and need to be monitored. With warmer and drier weather in the forecast, soil temperature is expected to reach favorable conditions for planting next week.
While soil temperature is an important determinant factor for early planting, the excess soil moisture has caused the most delays in 2017. Planting on soils that are too wet will cause overall soil compaction, sidewall compaction, and delayed emergence.
Previous field research has shown that the optimum corn planting period in Michigan is the beginning of May to the middle of May. (Read “When is the best time to plant corn in Michigan?” for more information.) Remember that any benefits from planting corn early can be quickly nullified by poor soil and imperfect weather conditions.