Irrigation and Management Tips

Stage I

During Stage 1, homeowners should maintain a deep infrequent irrigation schedule. This approach is recommended through out the year regardless of the water status. This approach to lawn watering, is better for the overall health of the lawn. It reduces incidence of some diseases and conserves water.

During Stage I designated times, apply enough water to adequately wet the soil to a depth of 6 inches. The following steps can be used to help determine how long to run your irrigation system to accomplish this.

1. Set out 5-6 open-top cans randomly on the lawn (cans with short sides like tuna or cat food cans work best).

2. Turn the sprinkler head or system on for 30 minutes.

3. Measure and record the depth of water caught in each individual can.

4. Calculate the average depth of water from all of the cans. For example you have used five cans in your yard. The depth of water found in the cans were as follows: 0.5"(1/2"), 0.4", 0.6", 0.4", 0.6". Add the depths together and then divide by the number of cans you used (5 in this case).

0.5"+0.4"+0.6"+0.4"+0.6"= 2.5"¸ 5 cans = 0.5" of water in 30 minutes (1)

5. Use a garden spade or a soil probe to determine how deep the soil was wet during the 30-minute time period. Push the probe into the soil. It will easily push through the wet soil, but will become difficult when it reaches dry soil.

6. Knowing how much water was applied in the 30-minute cycle and how deep that volume of water wet the soil, it is then easy to determine how long the sprinkler head must run to adequately wet the soil to a depth of 6 inches. (Example- The system put out .50 inches of water in 30 minutes wetting the soil to a depth of 3 inches. Therefore, 1 inch of water will need to be applied to wet the soil to a depth of 6 inches giving a run time of 1 hour.)

Last, look for runoff. If water is running from your lawn into the gutter, you need to use a split application method of irrigation. Run-off is addressed more completely later in this publication.

Drought stress symptoms will develop when the lawn needs water. It is important for the health of the turf that irrigation not be applied again until the grass really needs it. Symptoms of drought stress include grass leaves turning a dull, bluish color, leaf blades rolling or folding, and footprints persisting for an extended period of time after walking across the lawn. Drought symptoms may develop in as little as 3 days or not for 15 days. In most situations, symptoms will develop in 5 to 7 days. Therefore under stage I rationing, turfgrass quality should not drop.

Run-off can be a serious problem leading to significant water waste. Soil type and the application rate of the sprinkler system determine how quickly run-off will occur. If water is applied faster than it can move down into the soil, it can run off the site of application and be lost. Special attention must be paid to eliminate this type of water waste.

To Prevent Run-off:

1. Monitor the lawn during the course of several irrigation cycles looking for water running onto sidewalks, streets or gutters.

2. Note how long water was applied prior to run-off. This is maximum run time for any one irrigation cycle that will prevent water losses due to run-off.

3. Allow the soil surface to dry (30 minutes to 1 hour).

4. Change your irrigation timer to the new shorter time and begin watering again..

5. Continue this cycle until enough water has been applied to wet the soil six inches deep.

Other Considerations:

1. Continue an as needed mowing schedule, remembering to mow often enough to remove no more than 1/3 of the leaf blade at any one time.

2. Reduce your fertility program, keeping nitrogen levels low.

Stage II

The same approach can be used in stage II as was used in stage I. If the soil is thoroughly wet to a depth of 6 inches with each watering cycle, the lawn should be able to go a week between irrigation cycles. If necessary, use a hand-held hose to water those areas that show drought stress symptoms before the next allotted irrigation date. Make sure when doing so that you take the time to thoroughly wet the soil to the appropriate depth.

Other considerations:

1. Continue mowing as needed.

2. Reduce your fertility program, keeping nitrogen levels low.

3. Use a shower or fan type nozzle on your hose to help evenly disperse the water

Stage III

Irrigation during stage II becomes more difficult. You still need to follow a deep irrigation program to help maintain a healthy root system. However, most homeowners do not have the time or the patience to hand-water the lawn to a depth that is beneficial to the grass. The following is a list of three different approaches one might adopt during stage III of water rationing.

1. Water with a hose only those areas that are showing severe drought stress. Make sure that enough water is applied to effectively wet the soil to a depth of 6 inches. When puddling or run-off begins to occur, stop watering that particular area, let the surface dry and then resume watering. Continue this cycle until the soil is wet to the appropriate depth. Use a sharp probe or spade to help determine the depth of water penetration. Those areas should not be watered again until drought stress symptoms redevelop. This will be a time intensive approach, requiring daily attention. Time and lawn size will determine whether it is a viable option.

2. If time and patience are a limitation, or the yard is just too large, you may want to stop watering the lawn all together. Before using this approach, there are a few things a homeowner needs to consider. Most warm-season turfgrass species have the ability to survive short periods of drought stress. When the grass is under severe drought stress, it may go dormant. Dormant grass will be brown and may appear dead. Once watering or rain begins again, the grasses will recover, assuming the drought has not been too severe. Recovery will be slow and may take up to three months during the growing season before the lawn recovers completely. Grasses that are able to go dormant during drought are buffalograss, zoysia japonica, and bermudagrasses (for droughts less than 6 weeks). Other grass species do not possess this type of drought tolerance mechanism. Significant turfgrass loss can occur if these species are allowed to experience severe drought stress for an extended period of time. Therefore, you need to understand the strengths and weaknesses of your particular turfgrass species. (Table 1) If the grass in your lawn possesses a strong dormancy mechanism, you should consider stopping irrigation altogether and allow the turfgrass to go dormant. On the other hand if your grass does not have a dormancy mechanism, and it is allowed to experience long periods of drought stress, a significant amount of lawn may die and need to be replaced after the drought has ended.

3. Utilize a combination of the previous two approaches. Water only high priority areas and allow other areas to go dormant or die. High priority areas are determined by an individual's specific needs and preferences. If the back yard is utilized more than the front, it would be the high priority area. Portions of the front yard might be a priority in order to maintain an aesthetically pleasing landscape. This approach will allow the homeowner to maintain green turfgrass in important areas of the yard, saving both water and time.

Other considerations:

1. Continue an as needed mowing schedule were no more than 1/3 of the leaf blade is removed at any one time

2. Maintain a low to no nitrogen fertility program

3. Maintain a moderate to high potassium fertility program (based on soil tests)

4. Use a shower or fan type nozzle on your hose to help disperse the water when hand watering.

Figure 1 - Strength of dormancy mechanisms in common southern turfgrass species

Stage IV

The approach for this rationing stage is quite easy - do not water the lawn. Buffalograss, bermudagrass and some of the zoysiagrass varieties will probably survive under no irrigation. They will eventually go into a dormant state until the drought stress is eliminated at which time they will come out of dormancy. Depending on the duration of the drought conditions, survival rates should be high for these three species.

St. Augustinegrass, Seashore paspalum, Centipedegrass, Tall Fescue and some other grass species may be severly injured or die if exposed to extended periods of drought. Dead areas may be seeded, sodded, plugged or sprigged after drought conditions end. The best method of establishment will be determined by the species and variety of selected turfgrass. Contact your local Extension Agent if you have any questions.

Other considerations:

1. Continue mowing as needed, removing no more than 1/3 of the leaf blade at one time

2. Stop any nitrogen fertility program, until drought restrictions are lifted

3. Maintain a moderate to high potassium fertility program (based on soil tests)