Crops develop by heat, not by the calendar. Growing Degree Days (GDD) add up the useful warmth a crop receives each day above a base temperature: about 5 °C for canola. A warm week moves a crop further along than a cool one, even though both are seven days long.
Because each growth stage arrives at a fairly predictable heat total, a running GDD count tells you when a paddock will reach its next stage, and when decisions such as nitrogen timing matter most.
Daily GDD = (max temp + min temp) ÷ 2 − base temp
Example for canola: a day of 17 °C and 5 °C gives (17 + 5) ÷ 2 − 5 = 6 GDD.
In the AgrivaCT pilot
In the canola pilot, GDD are counted from each zone’s sowing date using that zone’s daily temperatures, so every zone has its own stage.
