Is it warm enough to plant corn?

Marilyn Thelen<thelen22@msu.edu>, Michigan State University Extension -

Soil and water temperatures below 50 degrees Fahrenheit can damage corn seed and reduce yield.

Soil temperatures at 40 F. Taken April 28, 2015 in the early morning in soybean stubble. All photos: Marilyn Thelen, MSU Extension
Soil temperatures at 40 F. Taken April 28, 2015 in the early morning in soybean stubble. All photos: Marilyn Thelen, MSU Extension

The first 48 hours corn seed are in the soil is critical. If soil temperature is below 50 degrees Fahrenheit during this time, it can lead to chilling injury and ultimately reduced yield. Temperatures at this stage are critical because this is the time water rushes in the seed to rehydrate the cells. This process is called imbibition. If the water is cold, below 50 F, it can damage the cells and abort growth of the radicle (root) and coleoptile (shoot). Seeds may not germinate or may express reduced growth.

To determine the risk of chilling injury, check the soil temperature in the field.

  1. Check average soil temperature for the last seven days.
  2. Check the air temperature predicted for your areas for the next 48 hours after planting.
  3. Test the soil temperature in your field. A meat thermometer works well for this. Take the temperature just before dawn (the coldest time of day) and at the depth the seed will be placed.

If soils are less than 50 F or are expected to fall during the 48 hours after planting, wait to plant.

The week of April 20, 2015 was cold. According to Michigan State University Enviro-weather, the average soil temperature in the last seven days was a high of 45 F and low of just 41 F. Average air temperatures for the next 48 hours (April 28-29, 2015) is projected to be 48.5 F. In fact, May 1 is the first day the average temperature is expected to be over 50 F, according to the Ithaca Enviro-weather station.

Thermometer in soil showing 51 degrees Thermometer in soil showing 48 degrees
Soil temperature at 3:30 p.m., April 27, 2015 near St. Johns, Michigan. Fall chisel plowed ground is 51 F (left), soil in no-till corn stubble is 48 F (right).

We are, however, expected to have increasingly warmer weather this week, so now would be a good time to check the soil temperature in the field. If it reaches 50 F just before dawn and the forecast is for over 50 F for the next 48 hours, it’s time to plant!

Selecting corn hybrids that are more tolerant of cold conditions at planting can also decrease the risk of chilling injury. Planting corn in mid-Michigan around May 1 this year looks like a good bet.

Resource

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