Choosing a soybean variety in Ontario has traditionally been based on Crop Heat Units (CHU). The CHU system is used to calculate plant development based on temperature. This works well for corn, but is not accurate for predicting soybean maturity. Soybeans are unique in the way they grow. Development is effected by temperature as well as day length, or photoperiod. In order for a soybean plant to begin flowering it requires a minimum day length as well as adequate temperature, generally the higher the temperature the faster it will begin to flower. Due to photoperiod sensitivity, varieties are adapted for growth in a relatively narrow latitude range.

Read the entire report here: New Ontario Soybean Maturity Map