Soil temperature is one of the primary factors controlling seed germination. Corn germinates when soil temperatures exceed 50 degrees F, soybean germinates when soil temperatures exceed 50 to 55 degrees and sorghum requires soil temperatures above 60 degrees for germination.

The University of Missouri maintains a network of automated weather stations throughout the state. Twenty two of the weather stations report soil temperature at two inches below a bare soil surface. Five of these locations also measure two-inch soil temperature under a ground cover of soybean or corn stubble.

Missouri soil temperature data is easily accessed over the internet at the web site, http://agebb.missouri.edu/weather/stations/index.htm. At this site there is a link to a page summarizing the previous day’s high and low soil temperature at the 22 locations reporting two-inch soil temperature. This Web site also has links to 11 weather stations around Missouri that provide live reports of current weather conditions including two-inch soil temperature.

Soil temperature is also a component of the University of Missouri’s Horizon Point Custom Weather system that sends site-specific weather reports directly to your e-mail. The Horizon Point e-mail report will include a graph of the average daily two-inch soil temperature for the past two weeks at the weather station closest to you and the long-term average soil temperature for that location (see the example figure below). This e-mail report will allow you to track trends in soil temperature and determine if current soil temperatures are above or below average. You can sign up for the Horizon Point Custom Weather system at http://agebb.missouri.edu/ horizonpoint/ or by contacting Nick Jaskolski at 573-884-6311 or at HorizonPoint@missouri.edu.

John Lory
Division of Plant Science and
Commercial Agriculture Program