If you need to roll your soybean field (to press stones down, so they are not above the ground) and plants have already emerged, it is strongly recommended to wait until they reach the first trifoliate stage and the daily temperature is above 25°C.
Most important is to pick a day, the hotter the better, when the plants are pliable (even if they are in second trifoliate or a bit later) and the soil surface is not too wet. Soft ground can also help. Always roll only a small test area first, and then get out on your hands and knees and examine those soybean plants to determine if rolling is damaging them or not. For those solid seeding, we recommend doing a stand count using a hoop to evaluate the job you are doing. Count all the plants in the hoop, then re-count the damaged ones and determine what percentage of plants are damaged in your test area. If the number of damaged plants is under 10% of the total plant stand, then continue rolling the rest of the field.
If damage is above 10%, wait to roll a small test area and reassess on a hotter day, even if soybeans have advanced past the first trifoliate stage. It usually takes Manitoba soybeans 7-10 days to advance from first trifoliate to second trifoliate stage.
Click here for more information about rolling soybeans in Manitoba.