As the ground thaws, farmers may be eager to get seeds in the ground, but planting to early could be a devastating mistake.

"Seeds don't grow in the bag, right?" said SDSU Extension Agronomy Field Specialist David Karki. "But at the same time, there's certain things we have to look at, too."

On March 29, Karki published an article about soil temperature and germination, which warns people against planting on a pre-determined date.

According to Karki, all crops require different soil temperatures to grow properly. He said corn and soybeans are warm-temperate crops, which require soil temperatures of at least 50 and 54 degrees, although the best germination occurs at over 60 degrees.

Because of that, Karki recommended producers in southeastern South Dakota to start planting corn and soybeans between May 1 and May 15, while those in the northwest should wait until May 12 to May 26, and planting too early could cause the seeds to die, especially if the soil is wet.

"They can't really sprout, and they'll just stay there and eventually get some soil-born disease, some pathogen, and just rot and die off," Karki said.

But waiting until the soil is too warm is a problem, too. Wheat germinates best in soil temperatures around 35 degrees, Karki said, and if the soil is too warm, yields and seed quality will suffer.

Stuart Preheim, a farmer from Freeman and a sales representative for Pioneer Hi-Bred, tracks soil temperature with a series of thermometers, which he places annually on April 1.

"I'm old enough to know those soil temperatures are important and very, very helpful," Preheim said.

Preheim checks the temperatures every day at about 8 a.m. to see how warm the soil was overnight. He targets 50 degrees for corn and 60 degrees for soybeans, and he'll typically start planting corn around April 15. He'll hold off on soybeans until about May 10.

But even if the soil temperature seems right, Preheim encourages everyone to watch nature as well, because if nearby trees are budding late, it's a sign the deeper soil is still cold, and that could cause problems for crops later on.

"You still got to know your soil temperatures, but you also got to look around and observe nature, too," Preheim said.

Preheim said his thermometers cost about $5, and there's always interest in his readings from the surrounding area.

SDSU Extension, too, tracks soil temperature with various weather stations across the state, including one stationed north of the airport in Parkston, according to SDSU Extension State Climatologist Laura Edwards.

The weather stations report soil temperature every 10 minutes, and a daily average is posted at climate.sdstate.edu every day.

On March 28, the average soil temperature 4 inches under bare ground in Parkston was 48 degrees, which is perfect for crops like alfalfa, oat and peas, which require temperatures of 45, 43 and 42 degrees, respectively.

Edwards encouraged all farmers to check the soil temperatures before planting, but she recommends watching for a three-day average because temperatures fluctuate.

"Even at 4 inches deep, it can fluctuate quite a bit day to day if you get a really warm day or a really cold day," Edwards said.

Edwards doesn't know how many farmers use the soil readings, but she said the tool is popular among agronomists.

And with more sensors being added every year, she hopes its popularity continues to rise, as similar stations are too expensive for many farmers to install on their own property.

"It's through the university, so we're trying to help as much as we can, and hopefully it's useful out there," Edwards said. "You can get them on your own, but they're not really cheap."