By John C. Fech and Brad R. Jakubowski
One of the most basic yet most important management practices is the efficient delivery of water to the turf and ornamentals on a sports turf facility. While all systems are less than 100 % efficient , implementing various techniques and adjustments will be a significant improvement. In most cases, only a small infusion of cash may be required to reap the rewards of making positive upgrades . An honest look at the system components — from orifices to pump stations to spray patterns — will provide the data to justify the short-term outlay of resources and provide a roadmap to the parts of the system that will produce the greatest return on investment.
SIGNIFICANT IMPROVEMENTS
“Significant improvements” and “positive upgrades” can be explained in several ways , the first of which is basic human nature. Since an entire field of green grass is often thought of as the desired appearance — at least for coaches and spectators — the natural tendency is to run an irrigation system long enough to make sure that every part of a field is green, no matter how long it takes. Although that approach makes sense in a perfect world with perfect equipment, it breaks down quickly when imperfect equipment and less-than-perfect maintenance practices are involved.
When irrigation systems are investigated for efficiency, the broken parts are identified. Yes, broken, such as heads that don’t rise above the height of cut; bent risers; water thrown onto the track, dugout, shot put ring, bleachers and other non-turf areas; heads that don’t turn; and orifices that are clogged. The big problem comes into play when human nature encourages a sports field manager to run a zone until it produces green grass everywhere.
There are at least three consequences to these inefficiencies:
1. Turf health — Inefficient watering can harm turf by causing some areas to receive too much or too little water. Inadequate irrigation leads to root system retraction, while excessive watering fills soil voids, depletes oxygen, and promotes root decay and diseases such as Pythium root dysfunction and summer patch.
2. Water waste — Overwatered areas , while appearing green in the short term, result in significant waste of resources and contribute to inefficiency.
3. Player safety — Poor footing caused by overly wet areas can lead to player slippage and injuries, creating a serious safety concern.
FIRST STEP: A GOOD “LOOK-SEE”
"Turn it on and watch it run” is a great starting point for improving irrigation systems.
Grab a clipboard, put several sheets of graph paper in the hold-down spring and use a ballpoint pen to make a map of a field, landscaped areas surrounding a field or campus grounds. Draw in hashmarks, goal mouths, dugouts, coaches areas, player warm-up areas, trees, shrubs, groundcovers, fences, concession stands and others features that aren’t likely to change.
Turn on each zone for three to five minutes and use flags to mark each head. You’ll need to know their exact location later in the process.
In another color ink, draw in each irrigation head and designate it some wa , such as a capital letter H with a circle around it.
In another color ink, draw a square next to the head designation. This is where you will record the output of each head after it is run for a length of time. You could also use a separate sheet of paper to write in the amount collected. When a large number of heads are involved, a second sheet usually turns out to be the easier approach.
Run each zone in a particular area and make some general observations or field notes to record the flaws. Another option is to make a quick video with your smartphone to document the flaws. You might need evidence to show a decisionmaker when it comes time to approve upgrades, and a picture/video is worth a thousand word.
SECOND STEP: MEASURE AND RECORD
This is where the rubber meets the road ; where the real output is documented. As with most things in life, you get what you pay for in terms of the inputs for a valuable endeavor. When venturing into this activity, it’s worth doing it right by using high-quality water collection equipment. It’s readily available and not super expensive. You can buy the essential components for a baseball field for about $500.
Run each zone for 20 minutes, then record the amounts collected — noting metric system units/millimeters allows for a much easier comparison and uniformity calculation than using imperial measurements.
Using a straightforward chart like the one below will allow for both mathematical and visual comparisons.
Calculating uniformity: Average depth of lowest 25% of cans: divided by overall average depth of all cans: equals: %
Uniformity can be calculated by using the above formula or a simple division of the average depth of all cans. If there are drastic differences in amounts collected — such as 10 mm, 25 mm, 35 mm and 8mm in the same zone or adjacent zones — then it’s best to use the method that utilizes the lowest 25% of cans , as well as the overall average. Irrigation systems with lower than 60 percent uniformity should be adjusted for more uniform coverage.
THIRD STEP: FIX THE BIG FLAWS
Perhaps the biggest improvement in efficiency can be realized by identifying and fixing the biggest flaws, similarly to the method of calculating uniformity that includes the lowest 25%. Why? Fixing big flaws will make the biggest difference in terms of overall performance. Some examples are heads that don’t turn, leaking valves, heads that spray only vertically (a.k.a., geysers), and heads that do not rise above the height of cut of the turf.
FOURTH STEP: RE-MEASURE AND LOOK FOR GREATER UNIFORMITY
In order to carefully document the percentage of water savings after retrofitting , another check of the system output is required. The second audit may seem tedious, but is required in order to record the improvement in efficiency. A second audit also provides additional documentation for justifying the expense of the new and replacement parts.
FIFTH STEP: REDUCE BY 10 PERCENT
Trimming the runtime of all zones, or just the zones that are ultra green can be a real cost savings. For example, if you decrease the runtime of a particular zone from 30 to 27 minutes, it is unlikely that there will be a significant difference in turfgrass health, but you’ll save 10% on the cost of the water needed to keep the field green.
CALCULATE INPUTS AND PROJECTED SAVINGS
In one column, list all of the equipment and labor hours needed to conduct a proper water audit — items such as the cost of the measurement pieces; the number of hours required to lay out the map, install the flags, collection cups and plastic/steel rings; the time to calculate uniformity; and the time needed to order and assemble the collection equipment.
In an adjacent column, list the time and cost of the water needed to irrigate a field before the audit.
Next, construct a column with a projected 10% savings based on replacement of flawed parts and trimming the runtimes, where feasible.
Finally, a column with the calculated efficiency improvements, noting reduction in applied water, reduced runtimes and lower cost of applied water.
LIKELY RESULTS OF AN AUDIT
To gain perspective on how much land is occupied by turf in a typical sports field, the square footage must be calculated. Assuming a football field, with the dimensions of 360 feet by 160 feet, the minimum square footage is 57,600 square feet. Of course, many fields are larger than this, as they include some track and field accommodations, but for consistency, 57,600 will be used. Considering that 1 acre of turf = 43,560 square feet; thus 57,560 ft²/43,560 ft² = 1.32 acres .
The next important formula is for acre-inch, which is the amount water required to cover an acre of land one inch deep in water, which is 27,154 gallons.
Next, it’s important to calculate how much water is required to apply one inch of water to a minimal area football field: 1.32 acres of land. The calculation is 1.32 acres x 27,154 gallons = 35,843 gallons of water.
The natural follow up question is, “How much water would be required to irrigate this field during one week?” If one inch per week is required, then the answer is the same, 35,843 gallons. If rainfall is received, that amount should be subtracted from the required amount; if windy or high evapotranspiration conditions prevail, then additional water is required and should be added to the total.
Here’s where the calculations come alive: 35,843 gallons are required in a given week, and the system is running at 50% efficiency as documented by an irrigation audit, the total applied would have to be double what is desired because the driest areas are receiving half of what the adequately watered areas are receiving. Hence, 2 inches of water or 71,686 gallons would need to be applied for the week. This would obviously result in many areas being grossly overwatered.
If the irrigation efficiency is improved by 25%, from 50% to 75%, we can easily calculate the amount of water saved after upgrades and retrofits have been made. The new irrigation requirement would be 44,803 gallons instead of 71,686, which is a significant reduction. Even a modest improvement of 10 % would save 3,584 gallons from the original amount applied.
With just a 10% improvement in efficiency , and a conservative 14 weeks of watering, saving 50,000 gallons could be achieved in a reasonable amount of time: 3,584 x 14 = 50,176.
Here’s where a second point of enlightenment kicks in, as it is a rare situation where a sports field manager cares for only one football field. Most manage soccer, baseball, softball, lacrosse and many other sports, ranging from three to 20 fields overall. So, at a common municipal rate of $6 per 1,000 gallons, annual water cost savings for irrigating may be a minimum of $300 to $500 per field. This translates to potential savings in the multiple thousands of dollars. When you add up the water and cost savings from implementing various irrigation improvements, the benefits far outweigh the time and effort spent in the process.
John C. Fech is a horticulturist with the University of Nebraska-Lincoln and certified arborist with the International Society of Arboriculture. The author of two books and more than 400 popular and trade journal articles, he focuses his time on teaching effective landscape maintenance techniques, water conservation, diagnosing turf and ornamental problems, and encouraging effective bilingual communication in the green industry.
Brad R. Jakubowski is a turfgrass and irrigation instructor with Penn State University. He is a certified irrigation technician with the Irrigation Association and is an author and presenter covering multiple management areas within the turfgrass industry. He focuses his time on teaching best irrigation practices and troubleshooting, weather-based management decisions, soils and plant nutrition.