The warm spring could mature soybeans slightly faster than normal this year, according to one Purdue University Extension specialist. Shaun Casteel said that the warmer conditions this spring have increased the amount of heat units the soybean plants have received. Although farmers think the adage that applies to corn—the more heat units plants receive, the faster they develop—it has a slightly less direct impact on soybeans, Casteel explained.
Casteel told Indiana Prairie Farmer that soybeans are controlled by the photoperiod. This means that the length of day tells the plants when to turn from the vegetative state to the reproductive state.
He explained that while soybeans are more controlled by exposure to the amount of daylight, temperatures also play a role in soybeans’ maturity.
“The ratio is typically three to one, meaning that three days of early planting may move maturity up one day from what would be expected based on photoperiod control alone. So soybeans of the same variety planted April 20 might mature six days earlier than those planted May 10, assuming temperatures are warm to normal and other factors don’t interfere,” Casteel told Indiana Prairie Farmer.