WHY DOES THE TURF NEED WATER?
Many people don't stop to consider that a lawn is made of nearly 1,000,000 turf plants in every 1,000 square feet. Like all plants, they require water from the soil to survive. About 10 percent of the water used by turf is to produce energy and growth. The remaining water is used for cooling, much the same way our body cools itself through perspiration. You've probably noticed that turf growing in shade requires less water than turf growing in full sun. Much of this difference is due to the fact that the shaded turf is cooler.

It is important to maximize the turf's use of water from rain and irrigation, but in order to do so you must first have selected the best adapted turf for your area. The predominant grass for the southern U.S. is the deeply rooted, heat, and drought hardy Bermudagrass. In hot, humid areas St. Augustinegrass, Centipededgrass, or Carpetgrass can be used. In more temperate climates where cold winters and mild summers are found it's wise to choose from the Bluegrasses, Ryegrasses or Fescues. Tall Fescue is best for areas that occasionally experience very hot summers and cold winters. Mid-Atlantic states have these conditions. Check with your county extension agent or turfgrass sod producer to find out what types of lawns perform best in your area.

WHERE DOES THE TURF WATER COME FROM?
Turf gets its water from the soil. The soil supplies rain or irrigation water to the lawn's root system. In cooler, more temperate climates rain meets most of the turf's water needs except perhaps during the hottest months. In hot, dry climates irrigation is an absolute necessity through most of the year to maintain a useful lawn surface.

Soil serves as a reservoir of air, water, and nutrients for the lawn roots. A good soil lets both water and air move easily in and out of it. It does not become waterlogged or dry out too easily. Ideal soils have enough sand to keep them open, but enough clay to let them hold on to some water and nutrients. Loams and sandy loams are best. Soil depth is also important. A deeper soil will hold more water and will have more turf roots to take up water and nutrients. This means less frequent watering and fertilizing. A minimum of 4 inches of soil is required to prevent the need for daily watering in the summer.

IRRIGATION.
Using irrigation can provide you with a near perfect lawn during most of the growing season. It allows you to maintain a healthy turf during drier weather, control growth and color, and apply lawn amendments that may need to be watered into the soil.

A simple irrigation system is a hose and sprinkler that you move around the yard. These are actually very effective as long as you remember to move the sprinkler. Most home supply stores now carry irrigation clocks that screw onto your homes hose bibs so that you can't forget to shut it off. It allows you to run the system when you are not around or asleep.

More complex irrigation systems include irrigation time clocks, in-ground plumbing, and multiple valves for partitioning the lawn into irrigation zones. These systems, when properly designed, give you a lot of flexibility and control over your watering. A good automatic irrigation system allows you to irrigate sunny and shaded lawn areas for different lengths of time, apply water at rates that do not cause runoff or ponding, and irrigate dry lawn areas without having to water the rest of the lawn. Remember though, it is the management of an irrigation system that saves water and produces a good lawn, not the expense and complexity of the irrigation system itself.

SOIL MOISTURE SENSORS.
Several manufacturers now produce probes that will override the irrigation schedule entered on the control clock.
The sprinkler valves will not be allowed to open when the sensor detects that the soil is moist. Some sensors control the entire irrigation system. This is fine for very uniform lawns. Most lawns are variable though and sensors have been developed to control only specific zones of the turf. With this type of sensor the areas needing water will get it while the already moist areas will not. Placement of soil moisture sensors is critical. Placing a sensor in a dry spot will mean that the system will be overwatering the turf outside the dry spot. Placing a sensor in a wetter location means that drier locations will usually suffer drought stress in between irrigations. Try to pick a location that is not too dry, or use multiple sensors. On a much simpler level, many department stores and garden supply shops sell portable moisture probes that operate off of 9-volt batteries. You can push these into your lawn and get a reading of whether your lawn is wet, moist, or dry. The ease and depth to which you can push a screwdriver into the soil is also a very useful way to gauge soil moisture content.

HOW MUCH WATER DOES A LAWN NEED?
The amount of water a lawn needs usually goes up with the following: desired lawn quality, use of the area, intensity and duration of sunlight, when rainfall decreases or is poorly distributed over time, and the amount of south and west facing slopes. Sandier sites may not need more water but they will need more frequent irrigation than sites on loam. Check with your county extension office to get an idea of what the irrigation needs of lawns are in your area. A very effective way to determine when to irrigate your lawn is to observe the lawn itself. Professional turf managers do this despite all of their turf maintenance resources. Does your lawn appear lush, but not wet? Do the turf leaves spring back up in a few minutes after they have been walked on? Can you push a screwdriver 5 to 6 inches into the soil easily? If you answered yes to these questions then the lawn doesn't need to be watered. Irrigate when parts of the lawn appear to change color (usually from blue or green to grayish blue), the turf leaves begin to roll, the turf stays down after being walked on, and you can't push a screwdriver into the soil easily. By watching your lawn regularly you can get a feel for how often and where you need to water. When it is time to irrigate apply one-quarter inch of water with your sprinklers. After a few minutes, use a screwdriver to see how far the water has moved into the soil. Make another application of water if it hasn't wetted the soil down to 5 or 6 inches. The idea is to keep the soil moist, but not wet and sticky.

CYCLE-SOAKING.
Water will usually run off of sloped areas and puddle in clayey or compacted areas when you irrigate. In these situations the irrigation water ends up in the street or just evaporates from the puddles that are formed. You'll need to cycle-soak your irrigation system to prevent this loss from happening. The term 'cycle' refers to how long you can run the irrigation system until runoff or puddling occurs. 'Soaking' refers to the amount of time it takes for the water to move into the soil. For the sake of simplicity let's say that your irrigation system will deliver one-quarter inch of water in fifteen minutes time. However, after five minutes of irrigating the water begins to puddle. After one hour the soil has absorbed the water. To avoid wasting water, but still put down one-quarter inch of water you'll need to run the irrigation system three times for 5 minutes with a one hour soak period in between each irrigation cycle. This is fairly convenient if your irrigation system is hooked to an irrigation clock. Remember that time clocks are also available for hose bibs too!

WHEN IS THE BEST TIME TO WATER?
Evenings and early mornings are usually the best time to irrigate. Wind and evaporation are at their lowest at those times. Wind will carry water away from the area to be irrigated and evaporation doesn't let as much water enter the soil.