This is a system that is usually installed by the builder at the time of construction. The purpose of this system is to add moisture to the soil in small amounts during dry conditions. This added water keeps the soil moist, benefitting several things:
The sprinkler system is just like any other system (car, home a/c), that needs preventative maintenance each year. This is best done in the spring to correct any abnormal conditions. When this is done, the trees and shrubs grow to add value to the property. The moist soil also reduces the risk of foundation damage.