Forming a sod roll

A roll forming mechanism can include a passive roll-up mechanism that initiates the roll and an active roll-up mechanism that completes the roll. The active roll-up mechanism can include an upper conveyor that is rotated in different directions. The upper conveyor can initially be rotated in a direction opposite that of an inclined conveyor to cause a forming roll to advance along the inclined conveyor. The rotation of the upper conveyor can then be reversed to cause the roll to be completed. Then, the upper conveyor can again be rotated in the direction opposite that of the inclined conveyor to cause the completed roll to be transferred towards the stacking conveyor. The amount by which the upper conveyor is rotated in the reverse direction can be based on a detected length of a tail of the forming roll.