The researchers studied how the timing of tillage and planting affects weed populations and mechanical weed control in soybean fields. They found that delaying soybean planting from mid-May to early-June reduced weed numbers and losses in yield from weeds. Herbicide treatments worked equally well regardless of planting date, but using rotary hoeing and cultivation was more effective when planting was delayed. Early-planted soybeans generally did better with herbicides, but delaying planting reduced weed numbers and allowed mechanical weed control to match herbicide results. While delaying planting can reduce weeds and improve mechanical control, it may also lead to lower soybean yields.