SportsTurf provides current, practical and technical content on issues relevant to sports turf managers, including facilities managers. Most readers are athletic field managers from the professional level through parks and recreation, universities.
Issue link: https://read.dmtmag.com/i/54529
MOISTURE SENSOR OPTIONS Another option to assist with irrigation scheduling is the use of moisture sensors. Typical systems using moisture sensors have one or more sensors placed in the rootzone of the irrigated area. These sen- sors will either inhibit or shut down an irri- gation cycle once optimal soil moisture levels are present. A simple tool to use as a reference of the level of soil moisture is the tensiometer. These devices are installed in the rootzone similar to moisture sensors, but provide a gauge that can be visually ref- erenced for the status of soil moisture. Regardless of any technologies being employed, it is important to note that hav- ing an efficient system is paramount to ef- fectively using your limited water resources. It is a good idea especially on older systems to perform a tune-up before addressing scheduling concerns. During this site inspection the system should be checked for damaged and leaking heads and to ensure heads are level and unob- structed. At this time the pressure should also be checked at the nozzle to verify the optimum manufacturer pressure recom- mendations are met. If the pressure is too high, pressure regulation at the valve should be considered since high pressure can hamper efficiency just as badly as low pressure. If low pressure is observed refer to manufacturers nozzle data. Often smaller nozzles can be used to help reduce flow and restore pressure and nozzle efficiency to the system. GOING MONTHLY An irrigation schedule should be created for each month of the growing season. This will serve as a base schedule that will typi- cally require only minor adjustments with the exception of extreme weather events like prolonged rain or above average heat. The first step in this process is to collect historic or average evapotranspiration rates for the local area. This data can often be accessed through a water purveyor website or by an internet search for the best avail- able local source. Once this data is gath- ered, you can derive how many inches of irrigation water is needed by plant type. The irrigation schedule would then be built to replace this lost moisture. An additional consideration of the effi- ciency of the irrigation system components also plays a role. Since no irrigation system is 100% efficient, additional irrigation will need to be applied to compensate for the difference between the plants needs and the ability of the irrigation equipment to apply the water. As a general rule, rotary sprinklers range in efficiencies from excel- lent at 80% or higher, to a general average in the 70% range. Spray sprinklers tend to be less efficient than rotary with the high range being 60% and an average around 50%. Many systems with pressure, flow, and maintenance issues can fall well below these averages. Irrigation system audits are highly recommended to understand true system efficiency. Often times, the cost of a full water audit will provide a reasonable re- turn on investment through potential ir- rigation schedul- ing water savings. Soils can be thought of as your water reservoir and soil type plays a significant role in deter- mining how often and to what duration irrigation needs to be applied. For example, sandy soils do not offer as that will drastically decrease, especially as you approach the soils water holding ca- pacity. It is important to keep in mind plant roots do not seek water; rather only grow where water is present and your irri- gation schedules should be designed to provide more infrequent, deeper watering cycles. Frequent, short irrigation cycles typ- ically only provide moisture in the first few inches of the soil. This will create a shallow moisture reservoir and lead to shorter rootzones and less drought tolerant turf. As you prepare for your up- coming growing season, assess and repair the irrigation sys- tem at spring start up and gen- erate an expected monthly irrigation schedule based on your local evapo- transpiration rates. If your >> PRESSURE REGULATION at the valve can immediately solve high pressure issues that can lower sprin- kler performance. Hunter's Accu-Sync pressure regulator shown here. much water holding capacity as a clay soil. However, sandy soils are able to absorb water being applied over a longer period of time before irrigation run off begins to occur. Clay soils are the opposite, and gen- erally require several short sprinkler run times before the desired amount of water is applied to the rootzone. Simply running the irrigation system and observing the amount of run time until runoff occurs is a useful way to help determine the length of irrigation run time your soil can handle. An important note to consider when determining sprinkler run times is that soils generally have a high initial intake rate budget allows, strong con- sideration should be made for employing irrigation system audits and new technologies like smart controllers or to help achieve optimum water savings for greater safety and playability. There are many knowledge bases in the irrigation industry that can assist with the education and consulting of an irrigation system. The following websites offer differ- ent educational resources and net- working opportunities: • http://www.water.ca.gov/wateruseeffi- ciency/landscape/ • www.irrigation.org (Irrigation Associa- tion) • http://www.atinet.org/cati/cit/ (Center for Irrigation Technology, Fresno) • http://www.asic.org (American Society of Irrigation Consultants) • http://www.stma.org/ (Sports Turf Managers Association) ■ Troy Leezy CID, CLIA, CWCM and Mar- keting Manager at Hunter Industries www.stma.org SportsTurf 39