Turfgrasses are among the first plants to suffer from lack of water since they are naturally shallow rooted as compared to trees and shrubs. The groundskeeper should encourage deep root growth by watering so that moisture penetrates the soil to a depth of 8 to 12 inches. Failure to apply enough water will promote shallow root systems that can be easily injured during hot, dry summer weather (Figure 13-13). Infrequent, deep water­ing is much preferable to daily, shallow watering. The quantity of water applied during an irrigation will depend on the time of day and the type of soil. Clay soils allow slower water infiltration than coarser textured sandy soils, but clay soils retain water longer. Therefore, less water may

figure 13-13. Deep watering promotes deep, healthy root growth. Shallow watering promotes shallow rooting and leaves the grass susceptible to injury by drought. (Delmar/Cengage Learning)

figure 13-14. This revolving sprinkler covers a limited area and must be manually moved to each new location. Wind gusts can affect the evenness of the coverage. (Delmar/Cengage Learning)

need to be applied to clay soils or the rate of application may need to be slower or both. The amount of water given off by a portable sprinkler can be calibrated once and a notation made for future reference. To calibrate a portable sprinkler (Figures 13-14 and 13-15), set several wide-topped, flat-bottomed cans with straight sides (such as coffee cans) in a straight line out from the sprinkler. When most of them contain the amount of water needed to penetrate 8 to 12 inches, shut off the sprinkler and note the time required. Start by applying one and one-half to two inches of actual water and check its depth of penetration; then adjust accordingly. Permanent and computer-controlled automatic irrigation systems are common in large turf installations. They turn on and off by timers and dispense a predetermined amount of water through valves that pop up for use and disappear out of sight afterward. Such systems are sophisti­cated and costly (Figure 13-16).

figure 13-16. An automatic lawn irrigation system in operation (Courtesy Weather-Magic Irrigation)

figure 13-17. A powered reel mower (Courtesy medioimages/Photodisc)
figure 13-18. Reel mowers provide the best quality cut. (Delmar/Cengage Learning)

The best time of day to water lawns is early morning. Watering later in the day is inefficient due to greater evaporation. Watering in the early evening or later should be avoided because of the danger of disease; turf pathogens thrive in lawns that remain wet into the evening. The lawn should have time to dry before the sun sets.