Crop planting guide: Soil temperature and germination
BROOKINGS — Successful crop production to maximize profitability starts at planting.
“Seed germination, one of the key elements of good crop stand, is largely dependent on soil temperature,” said David Karki, SDSU Extension agronomy field specialist. “Regardless of where you are located, it is hard to go out and plant on a pre-determined date because of year-to-year weather variability.”
Karki explained that the minimum soil temperatures required by different crops for germination can vary widely, and are reached on different dates each year.
“Small grains such as wheat, oats, barley, rye, etc. have lower germination temperature requirements than row crops, such as corn and soybeans,” Karki said.
To help growers estimate their 2017 planting dates, Karki outlines germination temperatures based on South Dakota crop requirements.
Among field crops grown in South Dakota, wheat has the lowest soil temperature germination requirement at around 35 degrees Fahrenheit.
“If the soil temperature is suitable and 30-day forecast shows above freezing temperatures, growers can consider seeding spring wheat early,” Karki said.
Early planting: March 25 – April 15: The earliest planting of spring wheat is suggested for Southeast and Southcentral areas of the state.
Late planting: April 8 – April 27: The latest planting date is suggested for Northern regions in the state.
Corn and Soybeans
Corn and soybean are warm season crops that require fairly high soil temperatures for germination.
“Corn and soybean seeds can be vulnerable to chilling injury if water in the soil is cold, especially from melting snow,” Karki said.
Germination temperature for corn is about 50 degrees Fahrenheit whereas, soybeans require slightly higher temperature at 54 degrees Fahrenheit.
However, seeds of these two crops have shown the best germination at warmer temperatures of 60 degrees Fahrenheit to 70 degrees Fahrenheit.
Early planting: May 1-May 15: The earliest suggested planting date for corn is for the Southeast region of the state.
Late planting: May 12-May 26: The latest planting date is suggested for the northwest region of South Dakota. Similar dates are true for soybean.
Other important South Dakota crops require germination soil temperatures of the following:
Alfalfa: 45 degrees Fahrenheit.
Oat: 43 degrees Fahrenheit.
Pea: 42 degrees Fahrenheit.
Sorghum: 65 degrees Fahrenheit.
Sunflower: 60 degrees Fahrenheit.