Crop Germination – What Soil Temperatures are Needed?

Soil temperature drives germination and seedling emergence, so how cold is too cold?  What is your soil temperature at your targeted seeding depth….today? Finally, when should you be measuring the soil temperature?

The following are the minimum temperatures needed for germination to begin in various crops.  These values should be regarded as approximate, since germination depends on factors other than just temperature.  But, if soils are too cool, germination will be delayed and cause uneven or poor seedling emergence.

 

Crop Temperature     (°C)
Wheat 4
Barley 3
Oats 5
Corn 10
Canola 5
Flax 9
Sunflower 6
Edible Beans 10
Peas 4
Soybeans 10

Sources: North Dakota State University Extension Service, Alberta Agriculture & Rural Development and Canola Council of Canada

Getting an accurate measure on soil temperature

Determine how deep you will be seeding. Then place your soil thermometer at the targeted depth. Take two measurements throughout the day: one in the morning (8am) and one in the early evening (8pm).  Average the two readings to determine the average soil temperature. The recommendation is to take readings for two to three days to establish a multiple day average and to measure at a number of locations in the field, to account for field variability.

Still not sure and short on time?  See the soil temperature data for various locations across Manitoba from the MB Ag-Weather Program: https://www.gov.mb.ca/agriculture/weather/soil-temperature.html.  This can be used as a guideline for an area, but in-field measurements are going to tell you what is actually going on in your field!

 

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