Over watering a lawn is much worse for the grass and trees than under watering a lawn because a lawn that is watered too much will starve the soil of oxygen. Air is extremely important to the health of the soil and to promote deep digging grass roots. The soil underneath your sod is composed of sand, silt, and clay particles – as well as porous spaces. … Without oxygen, the roots of the sod will suffocate and die, leaving the plant with a very shallow root system.