With the rising cost of water, ever evolving legislation and more expensive irrigation systems, turf managers are increasingly aware of the need to use water as carefully and wisely as possible. Effective and efficient turf irrigation is a combination of a number of simple, but essential, factors. These include good design and correct installation followed by operation and maintenance.
The design end of irrigation covers aspects such as sprinkler selection and positioning, correct pipe and pump sizing and a thorough evaluation of the available water. Installation needs to be carried out by experienced contractors who have an understanding of the key aspects of system provision along with the implications of sprinkler spacing and pipe sizing.
While design and installation are very much associated with new systems and upgrades, operation and maintenance apply to both new and existing systems. System operation comes down to providing ground staff and greenkeepers with training not only on the use of the equipment, but also on the principles of irrigation, as Revaho UK sports sales manager Graeme Francis explains:
"Factors such as how to calculate application rates so that the water can be applied by quantity, as opposed to by time, allow a direct relationship between irrigation and water consumption to be created. The implications of changing the rotation arc of sprinklers operating from the same valve, is another simple piece of knowledge that is essential for applying water to sports turf.
"By reducing the arc of a sports or golf rotary sprinkler from 360 degs to 180 degs without reducing the operating time by 50 per cent, means you end up applying double the amount of water. And that has both wastage and agronomic implications."
Supplying irrigation for horticultural and amenity purposes, Revaho is a Hunter distributor and provides pipes, fittings, tanks and cable to contractors nationwide. A recent introduction made by the company is SportsPro pipe. Made of PE100 material, this pipe has a thinner wall, but with greater strength, to give a larger internal diameter and carry more water than the PE80 pipe it replaces.
An irrigation audit is the most comprehensive method of assessing system efficiency. As Francis says: "By using a series of catch cans or cups uniformly spaced in a grid pattern across the irrigated areas, and then running the sprinklers for a set time, enough information can be gathered to calculate the uniformity of water distribution across the area.
"In addition, checks can be made on the operation of the sprinklers themselves. Do some rotate slower than others? Are the correct nozzles fitted and how much have they worn since being installed? Over time, the nozzle aperture will increase with wear and it is not uncommon to find that sprinkler flows have increased significantly and therefore more water is being applied than was originally calculated. Irrigation audits will highlight pressure variations at the sprinklers, which again can affect the amount of water passing through the nozzle and the distance it is thrown."
Irrigation audits also look at pumping systems, control system set-ups and programmes, and can provide extremely useful information on how a system can be adjusted or fine-tuned to provide the most efficient application of water.
"There are quick ways to get a broad evaluation of how well the system is working," says Francis. "In addition to the obvious observation of turf growth and vigour, an example of a simple way to get an impression of whether a system is operating at the right pressure is to watch the spray from the sprinkler. If the pressure is too high, the spray will be a fine mist without the steady of stream of water that is required to throw the water the correct distance to provide uniform coverage. If the pressure is too low, the water will comprise only large droplets, with no misting and the distance thrown will be short. A sprinkler working at the right pressure will have a combination of a steady strong stream throwing water to the distance and a curtain of finer mist under this stream with some light misting from the top."
Systems and components manufacturers continue to develop products for improved strength and reliability. Control systems also play a key part in irrigation precision and efficiency. The use of evapotranspiration calculating weather stations has been around for some time. But these devices have tended to be expensive and their use restricted to large golf systems.
Recently, Revaho UK introduced Hunter Industries' more accessible weather-related control - the Solar-Sync. This monitors local weather and adjusts irrigation run-times accordingly. It can be fitted to many of Hunter's controllers to provide lower cost weather-related irrigation regimes and hence allow optimisation of water usage.
Maintenance is an aspect of irrigation that is often overlooked, even forgotten, but there are some basic day-to-day operations that should be carried out - and not just to the system - to ensure efficient irrigation. These include adjusting sprinkler height, regular observation of sprinkler performance and keeping the turf around the sprinklers at a height that prevents disruption of spray patterns. Again, choice of components can help. Hunters' Total Top Servicing (TTS) rotors for instance, allow inspection and maintenance of all the sprinkler components without the need to dig around or remove the sprinkler from the ground.
The services of a sports turf or golf irrigation specialist should be considered for larger maintenance tasks such as winter drains, spring recommissioning and control system fault-finding and repair. Their expertise could improve water management, saving you money in the long run.
Sports turf irrigation is a combination of the turf manager's skill and art in assessing irrigation requirements, plus the science of irrigation principles and equipment development. With ongoing operator education and training, and the development of new products, modern systems will continue to make the industry's essential use of water as efficient as possible.
On the pitch
Supplied by dealer Ben Burgess, 10 John Deere MC75 3in and four MC55 2in straight nozzle heads have been installed by Irrigation Services (UK) at Norwich City FC's Carrow Road stadium.
The pitch, a Desso GrassMaster with natural grass reinforced with synthetic fibre, was installed in 2004.
"Being sand-based, the pitch needs a good, reliable watering system, as without this the grass can go off quite quickly," says head groundsman Gary Kemp. "With football today, watering is one of the main techniques used to make the ball zip about. In keeping with modern practice, generally we do a heavy watering on Friday, then on Saturday we water the pitch anything up to six times leading up to kick-off, again at half-time, plus another good soaking after the match - so the sprinkler gets a lot of use through the season."
The existing sprinklers were coming to the end of their life and needed replacing, so Kemp tried out one of the new John Deere heads last year. He was impressed with the results.
"For maintenance, all the new heads are serviceable from the top, so there's no need to dig them out each time," he says. "Another advantage is that no dirt can get into the heads, because of the way they are constructed - and the heads feature a dual flushing system that cleans them out automatically as they move up and down."
Designed for efficiency and precision while withstanding the rigours of golf tee applications, the new Toro Irrigation T7 Series Rotor can be used for new and retrofit projects.
With its near 6in pop-up height and large radius, it is suited to medium-sized tee applications. It has a number of features that should appeal to greenkeepers.
"My favourite feature is the Smart Arc easy arc-adjustment," says Toro Irrigation sales manager Robert Jackson. "This is a dial on the top of the sprinkler allowing you to adjust the arc from 45 degs to 360 degs for dry arcing upon set-up and in field. Smart Arc also returns the rotor to its original setting if tampered with - a handy feature for public golf courses."
The T7's high-efficiency nozzles are designed to deliver precise watering and long throw. A single port design ensures water is evenly distributed across the spray pattern. The Rotor's nozzle tree offers seven available nozzles for flexibility and ease of maintenance.
Available with a sturdy stainless steel riser, the T7 Rotor is robust and benefits from a five-year warranty. It's heavy-duty retractable spring and water-lubricated gear drive, together with the wiper seal, are independent to reduce sticking and leaks, adding to the sprinkler's durability.
For artificial sports field irrigation, Rain Bird has introduced the ELR. Noted for its temperature reducing ability and ease of maintenance, its is available as pop-up for underground installation and standard for installation on a riser.
A physical model of a transpiring leaf, which gives a continuous electrical output proportional to the rate of evaporation, the Evaposensor from Electronic & Technical Services can be used to optimise plant growth and save water in the landscape sector.
"Many large operations, notably golf courses will have computer-based systems with a weather station to estimate evapotranspiration rate. Smaller users will not and could benefit from the more cost-effective and affordable Evaposensor approach," says ETS director John Walker.
New from ETS, the Evapo-irrigation interface (Eii) integrates the signal from the Evaposensor and triggers irrigation when accumulated evaporation reaches a user adjustable target. Walker says: "Fitting an Eii transforms a simple timer into an intelligent controller."