4 Irrigation

Water is a fundamental element for physiological processes in turf such as photosynthesis, transpiration, and cooling, as well as for the diffusion and transport of nutrients. Precise water management is arguably the single most important turf practice for maintaining high quality golf turf. When the amount of water lost from the turf system by evapotranspiration (ET) exceeds the amount supplied by rainfall, the turf must be irrigated. Courses should maximize water use efficiency through proper irrigation, as this conserves water and decreases the likelihood of water quality impacts from runoff or leaching. Deliberate use includes having an efficient irrigation system, ensuring the system’s proper function, using only the amount of irrigation water needed to maintain healthy turf in playing areas, and incorporating cultural practices that increase the water holding capacity of soil.

4.1 Regulatory Considerations

NYSDEC requires water withdrawal reporting for any system capable of withdrawing more than 100,000 gallons groundwater or surface water per day. In accordance with the state water quality standards for flow, any withdrawal must also ensure that the existing best use of the waterbody from which the water is taken, such as protection of aquatic life, is not impaired. For more information on water withdrawal reporting and regulations in New York, see the Water Withdrawal Permits and Reporting web page. During times of extended drought, water use restrictions may be issued at the local level.

4.2 Irrigation Water Supply

Irrigation water must be dependable, reliable, and of sufficient quantity and quality to accommodate turf grow-in needs and ongoing maintenance. It must also pose no threat to public health.

4.2.1 Irrigation Water Sources

Irrigation water can come from several sources:

• surface water from ponds, lakes, or stormwater detention ponds
• groundwater from wells
• recycled water sources
• any combined supplemental sources from rainwater and stormwater collection

Golf course designers and managers should identify and use alternative water supply sources to conserve freshwater drinking supplies whenever possible. The routine use of potable water is not a preferred practice. Municipal drinking water should be considered only when no acceptable alternatives exist. In the northeast, irrigating with recycled water may become more common as the cost of water increases and the availability of fresh water decreases, especially in large metropolitan areas. Recycled water is defined as any water that has been treated after human use and is suitable for limited reuse, including irrigation. Such water is also referred to as reclaimed water, wastewater, and effluent water. Using recycled water may also be part of a nutrient reduction strategy to meet the Total Maximum Daily Load (TMDL) in impaired watersheds.

For more information on the use of recycled water on golf courses, see Using Recycled Wastewater on Golf Courses.

4.2.2 Irrigation Water Quality

Nonpotable water irrigation sources (such as recycled water or storage and detention ponds) should be tested regularly to ensure that the quality is within acceptable limits to protect soil quality and turfgrass performance. In addition, wells along the shore that supply potable water might need to be tested for saltwater intrusion.

The Irrigation Water Supply web page of the NYS BMP website provides detailed information on irrigation water quality parameters, including the following tables:

• “Summary of Irrigation Water Quality Guidelines”
• “Relative salt tolerance of turf species in NYS”
• “Irrigation water restrictions related to soil water infiltration”

Additional parameters such as pH and micronutrients may be valuable for detailed evaluations of water quality.

For additional information, see the following:

• Understanding Water Quality and Guidelines to Management, USGA Green Section Record.
• “Irrigation Water Quality Guidelines for Turfgrass Sites,” Penn State Extension.

4.2.3 Irrigation Water Requirements

Seasonal and bulk water requirement analysis can be conducted to determine water requirements under normal and worst-case scenario (e.g. extended drought) conditions. For more information on calculating water requirements and example calculations, see Chapter 3 of Environmental Best Management Practices for Virginia’s Golf Courses. To conduct these analyses, the National Centers for Environmental Information (NCEI) (formerly known as the National Climate Data Center) provides historical climate data and statistics on precipitation across 10 regions in New York.

4.3 Irrigation System Design and Installation

4.3.1 Site Assessment

A site assessment of the entire facility should be conducted prior to developing a system design. The site assessment should include site-specific features, such as water sources; soil types (see the Web Soil Survey for identifying site specific soil types) and soil physical properties; microclimates; slopes; sun, wind and shade exposures; and a seasonal and bulk water requirement analysis. Examples of how site conditions impact irrigation system design include soil properties, which dictate how much water is needed to complete deep and infrequent cycles of replenishing water in the root zone, and wind exposures that increase transpiration losses and create greater water requirements.

The site assessment should also evaluate the impact of design elements, such as design features and concepts, planned or existing turfgrass varieties, and planned or existing drainage systems. The system design should include a general irrigation schedule with recommendations and instructions on modifying the schedule to meet these site-specific needs.

4.3.2 Design

Irrigation systems should be designed to meet site requirements, to provide efficient, uniform distribution of water, to conserve and protect water resources, and meet state and local code. Detailed BMPs for irrigation system design are published by the Irrigation Association in 2014 Landscape Irrigation Best Management Practices.

For precise irrigation control, courses should consider using advanced irrigation control systems that can schedule each green, tee, and fairway separately and allow course managers to adjust for differences in microclimates and root zones. Weather stations that calculate and automatically program water replacement schedules also provide opportunities for more precise irrigation, as do soil moisture sensors placed in multiple locations. Additional features may include rain stop safety switches that either shut down the system in the event of rain or adjust schedules based on the amount of precipitation.

Where feasible, variable frequency drive (VFD) pumps and/or pump stations should be used. These systems only expend enough energy to meet the demands of the irrigation pump(s). VFD systems reduce water hammer to fitting, pipe, and sprinklers when systems are pressurized.

It is essential that all delivery systems install and maintain accurate metering devices. Being able to measure water use allows baselines to be established and progress in water conservation efforts to be tracked. Installation of water meters will become more critical as more regulatory and compliance obligations are imposed on users of water for irrigation.

4.3.3 Installation

To ensure maximum efficiency, the irrigation system must be installed per the design and specifications. The installer must ensure there is qualified supervision of the installation process and that a qualified irrigation specialist inspects and approves the system installation.

4.4 Irrigation System Maintenance and Performance

A properly working irrigation system is critical to ensure optimum operation. System checks and routine maintenance should be done for pumps, valves, programs, fittings, and sprinklers. A schedule of inspections and a plan for record keeping should be completed. Use of photography is especially helpful in recording installations/repairs of underground systems. The publication 2014 Landscape Irrigation Best Management Practices can be consulted for devising a schedule and a plan for record keeping.

4.4.1 Seasonal Maintenance

Winterizing protects irrigation system pipes from damage due to water expanding and rupturing the pipe walls and fittings. Most New York golf courses need to drain or used compressed air to remove water from lateral and mainlines pipes before temperatures drop below freezing.

4.4.2 Performance

To ensure that it is performing as intended, an irrigation system should be calibrated regularly by conducting periodic irrigation audits, such as catch-can tests and an annual irrigation audit, to check actual water delivery and nozzle efficiency. Nozzles can wear over time. This will change irrigation output and distribution. Nozzles should be replaced, depending on the manufacturer’s recommendation, to ensure proper function.

While routine inspection and audits can be performed by the golf course superintendent, a professional irrigation consultant is required for a detailed irrigation audit, which should be conducted according to the Irrigation Audit Guidelines published by the Irrigation Association. Ideally, this professional audit should be conducted at least once every five years.

4.5 Irrigation Management Decisions

Irrigation should be scheduled when soils reach 50% of the plant available water point, and the amount of water should replenish the root zone to field capacity. The infiltration rate, effective root zone depth, and estimated ET demand determine irrigation frequency and soak cycle needs. These are explained in the Manage Irrigation web page of the NYS BMP website, which includes information on estimating infiltration rates, calculating and using the potential evapotranspiration (PET), and monitoring soil moisture.

4.5.1 Deep and Infrequent Irrigation

Several studies have compared deep and infrequent irrigation (DI) to light and frequent (LF) schedules. DI was applied at signs of wilting and the soil was wetted to a depth of 9.5 inches. LF treatments watered daily to replace the ET lost and generally wetted the top 1.5-3.0 inches of soil. Both treatments were syringed as required to cool turf on hot days. The turf treated using DI had increased root and leaf carbohydrates, larger and deeper root masses, reduced thatch, and better overall quality throughout the season. This particular study only considered physiological factors and did not assess the risks of leaching.

Wetting soils below the root zone increases the risks of pushing nutrient and pesticide residues closer to groundwater. Other studies have demonstrated that turf pre-conditioned with deficit irrigation for a period of seven to 14 days withstands periods of drought and has a quicker recovery. Pre-conditioning improves stomatal conductance, transpiration rates, and photosynthetic capacity in subsequent periods of stress. However, letting soils dry completely has a negative effect on plants. Creeping bentgrass, perennial ryegrass, and tall fescue can be pre-conditioned replacing 60-80% of the water deficit. Kentucky bluegrass has much higher sensitivity to drought stress and should only be watered at 100% of deficit. Cool season turfgrass should not be watered below 40% of deficit. Even though Kentucky bluegrass has the greatest sensitivity to deficits, it has the highest resiliency to recover.

4.6 Water Conservation

The increasing concentration of the US populations in urban and suburban areas is leading to concentrated demand for water resources. This urbanization has begun to challenge the supply of affordable and plentiful fresh (potable) water for irrigation in New York State. Water suppliers in most of the northeastern US must double the supply capacity to meet demand in the summer, resulting in high infrastructure costs. Therefore, economic, social, environmental, and political pressures dictate that water is used efficiently and conserved on New York’s golf courses.

Golf course superintendents can maintain a landscape optimal for play, while conserving water, through effective course design and management. For example, reducing managed turf areas reduces water needs, maximizes rooting in areas that are irrigated, and improves the use of the water applied. In addition, a well-designed, properly maintained, and wisely used irrigation system ensures the uniform application of water and minimizes runoff.

Many irrigation BMPs result in more efficient water usage, such as improving the efficiency of irrigation systems. In addition, superintendents can reduce irrigation requirements through turfgrass management, such as minimizing maintained areas, maximizing rooting potential, reducing water lost through ET, and improving soil water storage where possible on sandy sites.

Turfgrass selection can also reduce irrigation requirements. The increased availability of improved turfgrass species and varieties provides an excellent opportunity to select the most well adapted turf to site conditions. If selected for drought tolerance, some turfgrass varieties require less water to survive and maintain playability.

The following NYS BMP case studies illustrate water conservation efforts undertaken at three different golf facilities in the state:

• Precision Water Management, North Hempstead Country Club, Port Washington
• Irrigation Upgrades for Water Conservation, Hollow Brook Golf Club, Cortland Manor
• Conserving Water by Installing Quick Couplers, GlenArbor Golf Club, Bedford Hills

4.6.1 Drought Planning

Extended droughts can occur in New York, and superintendents should be prepared to comply with any applicable local water use restrictions in times of drought and consider voluntarily restricting water use even when not required. NYSDEC publishes current drought conditions in New York and establishes four levels of state drought advisories (in increasing drought severity as follows: “watch,” “warning,” “emergency,” and “disaster”).

4.7 Irrigation Best Management Practices

Irrigation Water Supply

• Conduct a seasonal bulk water requirement analysis and a maximum bulk water requirement analysis.
• Identify appropriate water supply sources that meet seasonal and bulk water allocations for grow-in and routine maintenance needs.
• Use alternative water supplies/sources that are appropriate and sufficiently available to supplement water needs.
• Reclaimed, effluent, and other nonpotable water supply mains must have a thorough cross-connection and backflow prevention device in place and operating correctly.
• Post signs in accordance with local utility and state requirements when reclaimed water is in use.
• Use salt-tolerant varieties of turf and plants to mitigate saline conditions resulting from an alternative water source, if necessary.
• Assess irrigation water quality.
• Account for the nutrients in irrigation water when making fertilizer calculations.
• Monitor irrigation water regularly for dissolved salt content.
• Design and/or maintain a system to meet a site’s peak water requirements under normal conditions. Be flexible enough to adapt to various water demands and local restrictions.
• Install and maintain accurate metering systems.

Irrigation System Design and Installation

• Conduct a thorough site assessment prior to designing the irrigation system.
• Develop a written, site-specific Irrigation Management Plan.
• Seek assistance from irrigation professionals, such as from Certified Golf Course Irrigation System designers and WaterSense-certified irrigation consultants, and follow established BMPs related to system design.
• When possible, use precise irrigation control technologies.
• Incorporate multiple nozzle configurations to add flexibility and enhance efficiency/ distribution.
• Install irrigation pipes away from the green surface to avoid more substantial damages should pipe failures occur.
• Update multi-head control systems with single-head control systems to conserve water and to enhance efficiency.
• Install manual quick-coupler valves for site specific irrigation so these areas can be hand-watered during severe droughts.
• Install part-circle heads along lakes, ponds, wetlands margins, native areas, and tree trunks.
• Use part-circle or adjustable heads to avoid overspray of impervious areas such as roadways, sidewalks, and parking areas.

Irrigation System Maintenance and Performance

• Conduct visual inspections regularly to identify necessary repairs or corrective actions, which should be completed before further evaluation of system performance.
• Inspect for water distribution interferences, such as trees and other obstructions.
• Inspect for broken and misaligned heads.
• Check that the rain sensor is present and functioning.
• Inspect the backflow device to determine that it is in place and in good repair.
• Record any modifications to the As-Builts, including head and nozzle choices.
• Use photography to document any major underground installations/repairs.
• As part of winter preparation, flush and drain above-ground irrigation system components that could hold water.
• Remove water from all conveyances and supply and distribution devices that may freeze. Use compressed air or open the drain valves at the lowest point on the system.
• Change filters, screens, and housing; remove drain plugs and ensure any water is removed from the system. Secure systems and close and lock covers/compartment doors to protect the system from vandalism and from animals seeking refuge.
• Drain any above-ground pump casings that may have “trapped” water.
• Record metering data before closing the system.
• Secure or lock any remote irrigation components, including satellites.
• Perform pump and engine servicing/repair before winterizing.
• Recharge irrigation system in the spring with water and inspect for malfunctions.
• Review efficiency of above-ground electric motors annually.
• Evaluate pressure and flow to verify that the correct nozzles are being used and that the heads are performing according to the manufacturer’s specifications.
• Run catch-can tests to determine the uniformity of coverage and to accurately determine irrigation run times.
• Conduct an annual irrigation audit to facilitate a high-quality maintenance and scheduling program for the irrigation system.
• At least every five years, conduct a professional irrigation audit that follows established guidelines.

 

Irrigation Management Decisions

• Base plant water needs should be determined by ET rates, recent rainfall, recent temperature extremes, and soil moisture.
• Evaluate root zone depth on the course and do not irrigate beyond this depth.
• Use infrequent, deep irrigation to supply sufficient water for plants and to encourage deep rooting in fairways and roughs.
• Monitor potential ET and calculate plant available water to improve irrigation precision.
• Use soil moisture sensors to assist in scheduling or to create on-demand irrigation schedules.
• Use multiple soil moisture sensors to reflect soil moisture levels.
• Place soil moisture sensors in a representative location within the irrigation zone.
• Use predictive models to estimate soil moisture and the best time to irrigate.
• Use a journal to record the “indicator zones” that should be more closely monitored.
• Calibrate older clock-control station timing devices periodically, and at least seasonally.
• Avoid use of a global setting; make adjustments to watering times per head.
• Adjust irrigation run times based on current local meteorological data.
• Use a computed daily ET rate to adjust run times to meet the turf’s moisture needs.
• Manually adjust automated ET data to reflect wet and dry areas on the course.
• Irrigation rates should not exceed the maximum ability of the soil to absorb and hold the water applied at any one time.
• Visually monitor for localized dry conditions or hot spots to identify poor irrigation efficiency or a failed system device.

 

Water Conservation

• Use turf only where actually necessary, such as greens, tees, landing areas, etc.
• Use native plants in landscaped areas to reduce water consumption.
• Increase naturalized areas to reduce water consumption.
• Choose plants for buffer strips that don’t require supplemental irrigation.
• Voluntarily reduce water use during times of drought.
• Adhere to any local water use restrictions in time of drought.