Irrigation is one of the key cultural practices used in turf management. In general, irrigation supplements, not substitues for, rainfall except on very specialized areas or under extreme drought conditions.
Irrigation management must include water conservation practices. Lack of adequate moisture can result in stress, dormancy, and even death of turfgrass.
Variables to consider:
Knowledge of the water reserve in the root zone - on many turf areas, 75 percent of the root system is often found in the top 4 to 6 inches of soil.
With knowledge of soil water reserves and the actual daily evapotranspiration (ET) and rainfall information, it is possible to determine when the available soil moisture will be depleted and irrigation required.
An automated on-line system is available to help make this decision. Entitled TIMS (Turfgrass Irrigation Management System), it is a free web-based program which tracks daily ET and rainfall to provide site specific guidance about irrigation amounts and timing.
TIMS can be accessed at Turffiles.ncsu.edu/tims