In winter, tall fescue plants growing in clay-based soils may be lifted as soils heave during freeze-thaw cycles. In soils containing large proportions of a 2:1 expanding clay, such as montmorillonite, young turfs without a well-developed root system are most susceptible to heaving. Rolling presses plants back into soil and smoothes the soil surface. Turfs also are rolled when the uniformity of the soil surface is disturbed by the activity of earthworms and moles. Rolling usually is most effective when the soil is moist, neither too wet nor too dry. The total weight of a water-ballast roller depends on the quantity of water inside the drum. A tractor-drawn roller is preferred when smoothing the soil surface of turfs on slopes. A heavy motorized roller [e.g., 1360 kg (3000 lb)] may correct minor soil-surface irregularities in turf, although it will not compensate for poor planting bed preparation (Powell, 2000).