Bringing irrigation and agronomy together
26 June 2023
This article appeared in Golf Architecture magazine
Historically, golf course irrigation systems were somewhat a basic network of pipes, wire, control, and golf sprinklers, designed to deliver water to the turf. And during the 1980’s and 1990’s when a boom in golf course developments was taking place, this was sufficient.
More recently, the millennial drought, that impacted most of southern Australia through the early 2000s, led to changes in irrigation practices and turf management. During this time, the scarcity of traditional water sources, the enormous growth in recycled water availability, and the increased monetary value placed on water forced Superintendents and Turf Managers to become more efficient, more effective, with sustainability the focus.
Today, we see a new focus emerging, that being a holistic approach to turf management. This approach encompasses sustainable architectural design, targeted irrigation design, and catering for differing water and nutritional requirements, depending on the turf species, soil types, course areas and desired appearance.
The pressures around water availability, course running costs and changes to the climate are ongoing, as is the never-ending quest for golf Course Superintendents and Turf Managers to provide “perfect playing surfaces”. Player expectations at all levels are high and with plenty of golf courses to choose from, there is competition for green fees and memberships so quality playing surfaces are increasingly important.
As a result, we now see an irrigation system as having two key functions. The first is to apply water to manage soil moisture that is best suited to growing healthy turf or providing a playing surface suitable for golf. There can be a bit of conflict here as sometimes a Superintendent may feel the need to dry a surface down beyond optimal growing soil moisture, to provide the desired “firm and fast” conditions.
The second function of an irrigation system is to apply or “wash in” fertilisers or plant protection products. Getting these agronomic products to the right position or place on the plant or in the soil profile greatly improves their efficacy and reduces wastage, and in so doing provides savings in agronomic expenditure while working towards “perfect playing surfaces”.
At Living Turf, we refer to this concept of irrigation and agronomy combined as “IRRIGRONOMY”.
The importance of irrigation scheduling
Irrigation is also more involved than simply applying water every day, or every other day, for 20 minutes a cycle. Today, irrigation needs to be accurate, uniform, and specific if we want to provide optimum growing conditions or target a specific soil moisture. Water scarcity, increasing energy costs plus the fact that water has a direct impact on turf health means the need for precision irrigation is vital.
A good starting point is to understand the depth of water your system is actually delivering in millimetres (mm). Many turf management product labels specify a depth of water that needs to be applied to optimize their performance, so without an understanding of a system’s precipitation rate, we are really guessing and potentially compromising the product performance, not to mention money spent. However, the benefits of understanding your system’s precipitation rates extend further.
To truly understand the actual performance of the irrigation system, and to determine the precipitation rates the system is capable of, an irrigation audit is required, with a core activity being ‘catch-can’ testing. Performance and precipitation rates are the two key components that allow us to understand how to schedule golf course irrigation. A ‘catch-can’ helps determine these two components.
Quite simply, a ‘catch-can’ test utilises a series of conical shaped devices, positioned evenly over the target area which capture the water during an irrigation cycle. The water captured is measured and compared to all other catch cans. Distribution Uniformity (DU), is calculated by comparing the lower quarter of the can count with the average, expressed as a percentage. The higher the DU, the higher the irrigation uniformity.
With a completed ‘catch-can’ test, we can now understand the performance of the irrigation system, its health and how we can schedule irrigation to suit. At this stage and with some general observations we can quickly identify some root causes of poor uniformity. We can then plan the next steps in improving system performance, with some simple measures, such as changing nozzles, replacing rotors, levelling, and adjusting pressures.
We also need to establish what specific soil moisture you are wanting to achieve. Are you wanting to have your greens at a soil moisture content of 25% or are you wanting your fairways to be firm but not hard? To achieve this, we need to be able to determine a targeted soil moisture. And to manage soil moisture, we first need to be able to measure it. There are several tools in the market that can be used to determine soil moisture.
Once we have an idea of our system precipitation rate and target soil moisture and we have a means to measure it, the next challenge is getting there. How long do we need to irrigate for to achieve our targeted soil moisture? Do we apply in minutes, do we apply in mm, or do we replenish ET (evapotranspiration)? All these three methods correlate to a precipitation rate driven by time, with a key consideration being by soil type and profile conditions. However, in order for us to answer a key question being “how long do we need to irrigate for?” to achieve a certain irrigation depth, we need to have determined the actual precipitation rate for the specific area.
Increasingly we understand the importance of maintaining the right balance of air and water in the soil to benefit turf and surface performance by optimizing soil health. Understanding how much water to apply and where we are applying it in the profile can help us promote a growing environment for the biology below the surface that play such a crucial role in sustainable turf management.
Monitoring soil moisture can also help inform timing of practices such as wetting agent or penetrant use, compaction relief and aeration, which can be critical to the health of the turf and soil.
Improving system performance will ultimately provide a more uniform irrigation, at a known precipitation rate, that will lead to healthier turf through optimising growing conditions. The Lakes Entrance Golf Club, a hidden gem in Victoria’s east, did just this. The troublesome 4th green was always difficult to manage and struggled with consistent turf coverage. Brendan Dooley, Course Superintendent, was quick to identify that very poor irrigation uniformity was the probable cause. From there, Brendan, was able to simply replace the existing golf impact sprinklers with new, highly efficient golf rotors, lifting the distribution uniformity to 70-80%, where it should be. The 4th green is now one of the best on this spectacular course.
‘Catch-can’ tests also provide us with precipitation rate data which is critical information when it comes to irrigating in millimetres (mm). Chris Rogers, Course Superintendent at the Portsea Golf Club, has done ‘catch-can’ testing with the aim of understanding precipitation rates across all of his greens. For Chris, this was done to achieve two key objectives. Firstly, he now knows how long he needs to irrigate for to achieve a desired soil moisture. Secondly, as most agronomic product labels recommend washing in products to a minimum depth, Chris is able to calculate an exact run time, considering other factors such as forecast rain, recent coring activity and wetting agent usage. The end result, according to Chris, is definite water savings, greater agronomic efficacy and significant cost savings.
Talking technology, we really need some basic tools to monitor and manage irrigation and irrigation scheduling. Today, many golf course irrigation systems are software driven and all irrigate in minutes, ET and mm with the latest product even irrigating in rotor revolutions. Furthermore, soil moisture sensors, that can be buried below the soil surface, that report hourly to a web platform, updating moisture, salinity, and ground temperature, are an excellent tool. Alternatively, handheld instruments can be used to capture soil moisture data, then analyzed with instant feedback delivered to an app, to determine moisture below the soil surface. Needless to say, technology will be ever more present when it comes to managing golf course turf surfaces.
Managed turf that looks great, is healthy and plays well results from enormous effort and dedication from turf managers right across Australia and New Zealand. With a strategic approach, considering all factors and engaging support where needed, the solution for “perfect playing surfaces” is available.