Success with troubleshooting irrigation issues involves both the obvious and the hidden in terms of causal agents. Because of the large number of possible causes, it’s best to separate the possibility of irrigation system flaws from other maladies by using this process, an overall diagnosis scheme:
1. First, identify the plant. In this specific case, the cultivars of the species being grown. Some cultivars are more prone to specific diseases than others.
2. Consider known maladies that resemble the symptoms. Your years of experience will tell you that the visual cues you see could be directly associated with that which is responsible. In other words, it could be just what it looks like, so don’t overlook the obvious.
3. Consider the history of the site in terms of soil, recent pest problems, fertility programs, the actions of support groups or booster clubs, and recent game or tournament play. For example, if for budgetary reasons the amount or frequency of fertilizer applications has been reduced, the incidence of dollar spot is a distinct possibility.
4. Consider a “match” with any of the items identified in step 3 to be a partial cause. In fact, more often than not, low-performing turf is affected by many causes.
5. Consider the time of year. Certain maladies are more likely to be causal at certain times of the year. Leaf and stem rust tend to be problematic in the late summer and early fall while bipolaris leaf spot is likely to infect turf in mid to late spring.
6. Consider abiotic causal agents. One of which could be irrigation issues, especially if only minor levels or degrees of other causes are identified.
If you suspect irrigation issues
After working your way through the scheme above, shift gears and grind through a step-by-step approach to irrigation issues.
- Start with a “turn it on and watch it run” routine. Clipboard in hand, while the first zone is running, climb the steps of the bleachers and watch the heads turning from halfway up. After watching for a few minutes, move over to the opposite side of the field and watch from a different perspective. Take notes on gross flaws, such as heads not turning, bent risers, maladjusted timers, leaky heads, leaky valves, clogged orifices, low/high pressure, maladjusted spray patterns, etc. Use a sketch of the field to note the location of these obvious problems.
- Next, flag the heads. It’s a little easier to do this while the system is running, because after the system shuts off, it can be difficult to find them. However, unless you’re able to outrun a sprinkler, your clothes are going to get wet. Most likely, donning knee-high rubber boots and old jeans will be the reasonable approach.
- Confirm the occurrence of too much or too little output by probing the soil in various parts of the field and feeling the extracted core for the presence of moisture. Many devices will work well for probing. An actual soil probe is the most commonly used, but some information can be obtained from a long bladed screwdriver, a short piece of rebar, a cut-off golf club or a fishing knife. If it’s difficult to force the probe into the soil, it’s probably too dry. If a sloshing sound is heard during probing, then it’s probably too wet.
- Fix obvious flaws that have been identified in the first round of observations such as changing heads, replacing valves and readjusting the spray patterns. Irrigation systems are mechanical devices that can break down without warning.
- Next, watch the system run again. In this part of the protocol, the goal is to validate or document that the fix produced a visible change in system performance.
A test run with a premarked collection device.
PHOTO COURTESY OF SANTA BARBARA, CALIF., PUBLIC WORKS DEPT.
Rubber hits the road
Looks can be deceiving, so now it’s time to put some numbers on the output. The only way to know for sure that the repairs made after observation actually resulted in a significant improvement in system performance is to measure the output of each head.
Collection devices can be simple or sophisticated. The most important result is to measure output and compare collection devices/cans. On the advanced side, specialized graduated or funnel-shaped collection containers are set into stainless steel rings to be held in place while the zone is running. After a test run, simply lift the plastic container out of the ring and read the output; the containers usually are made with output markings similar to a rain gauge. The downside to using this system is that the premarked containers and rings are a little pricey, costing several hundred dollars per set.
Simple collection devices can work just as well. Tuna and cat food cans can also measure irrigation system output accurately, and a short 6-inch ruler is handy to measure output with the simpler approach. Regardless of which method you choose, record each can’s output on a grid and compare one to another. This second step will document additional areas/parts of the system that need tweaking and adjustments.
A hillside can suffice as a good location to observe a test run of an irrigation system.
PHOTO BY JOHN C. FECH.
Strive for uniformity
The underlying goal for irrigation on a sports field is to strive for uniformity in output. As such, place collection cans randomly in the field as well as directly adjacent to heads for measurement. A reasonable approach is to place a can 2 feet away from a head and another halfway between it and the next head (placing cans closer than 2 feet can result in blowing the can over during the run, rendering the reading of output totally inaccurate). Because certain parts of a field can be irrigated by one or more zones, it’s best to have enough collection devices to account for at least three zones to ensure accuracy of the test.
Comparing the results of a test involves looking at relative differences in output at different parts of the field. If more than a 10 percent variance exists between collection can amounts, consider tweaking the system with adjustments in run time, nozzle clearance and rotor choice. If more than a 20 percent variance exists, more significant changes should be considered. Keep in mind that windy conditions can cause distortion of the irrigation pattern. If gusts of wind occur during a test, retest accordingly.