Often a poor lawn can be improved by using proper maintenance practices, including mowing, fertilizing, watering, and pest control. In some instances, however, portions of the lawn must be reseeded. Usually one of two methods is used to re-establish a lawn: conventional or renovation. The conventional method involves killing existing vegetation, tilling the soil, and replanting. The advantages of conventional tillage include more complete control of weeds and undesirable grass, a smoother soil surface, and the opportunity to improve the existing soil by adding organic matter and sand. Renovation involves replanting without completely tilling the soil and often without destroying all existing vegetation.