Spring Soil Temperatures

 

 

 

Soil temperatures across South Dakota can be found online at the SDSU’s Climate and Weather website. Temperatures are measured at the 4-inch depth in bare and vegetation covered (under perennial plants) soils. A look at the map of automatic weather stations across South Dakota, shows that soil temperatures on March 20, 2016 at the 4-inch depth in bare soils ranged from 34 to 45 degrees Fahrenheit. The soil temperatures at a 4-inch depth for vegetation covered soils ranged from 33 to 40 degrees Fahrenheit.

 

The greater range of soil temperatures in bare soils is expected and makes sense. Vegetation insulates the soil surface from wind effects and evaporative water loss from the sun. Therefore vegetation-covered soils can hold more moisture. Moist soils have a higher specific heat than dry soils and are therefore not as sensitive to temperature fluctuations.

 

 

Soil temperatures are an important factor when considering planting dates for many crops. Recommendations for spring wheat include planting when soil temperatures are 34-36 degrees Fahrenheit. Oats and peas are able to germinate when soil temperatures are just slightly warmer around 38-40 degrees Fahrenheit. Sunflowers germinate when soil temperatures are at or above 45 degrees Fahrenheit. Corn and soybeans germinate better when soil temperatures are consistently at or above 50 degrees Fahrenheit.

 

Although soil temperature plays an important role in seed germination, it is also very important for seeds to be in moist soils. Soil moisture levels fluctuate across South Dakota this spring. The Southeast part of the state received ample moisture during the winter, but the Northwest portion of the state received little in the way of winter snows or moisture.