According to Dylan Hepburn of irrigation company GebCo, drip irrigation is the future of irrigation. Whereas conventional irrigation uses sprayers, sprinklers or nozzles to distribute the water from above plants, drip irrigation applies the water at ground level directly to the root zone and not from above. From here nature does the rest of the work by moving the applied water through the soil by means of gravity and capillary action.
Why choose drip irrigation?
When water is applied from above plants, as in conventional irrigation, the water being sprayed is susceptible to wind, overspraying and, ultimately, evaporation. Overhead sprayers often direct water onto paving, buildings and walkways, where the water runs off or evaporates, resulting in wastage. As drip irrigation is applied directly to the roots of plants, these problems do not occur. Drip irrigation is precision irrigation.
“Drip irrigation saves water, you won’t have any overspray, it is cost-effective and easy to maintain,” Dylan says. The system is easy for the homeowner to install – Dylan compares it to Lego, it can be installed in any shape and to fit any area needed.
Where to start?
Measure the area you want to irrigate and draw a layout to help you work out the amount of piping and fittings you will need. “The amount of drip you need is very easily calculated; all you need is the square metreage of the area you want to put under drip and divide it by the spacing of the dripper line you want to use. For example, Gebco supplies Techline 0.3, 0.4, or 0.5 at 1.6 LPH. Techline is the dripper line; 0.3, 0.4 and 0.5 is the different spacing you can get on a dripper line, or how far apart the water emitters are in the line, and 1.6 LPH (litres per hour) is the amount of water each emitter emits per hour.” The emitters are built into the line and are quite sophisticated, with pressure compensation, and are self-flushing and anti-syphon. A 0.3m line will need to be spaced 300mm apart, a 0.4m line 400mm apart, and so on.
Gebco has a calculator on its website – www.gebco.co.za – where you can type in the area you want irrigated in square metres, what type of soil you have, your tap’s flow rate (see box), and it will work out the amount of flow you need, how many zones and how much piping
Connecting it up
It is a good idea to connect your drip irrigation to an automated system to avoid overwatering, as Dylan says that users tend to overwater with drip irrigation. “With the 0.4m Techline in a square metre, you put down 10mm of water in an hour and your garden only needs 25mm a week.” Your drip irrigation system can also be connected to a rain tank; in fact rain tanks are perfectly suitable as drip irrigation can be run with lower pressures and flow compared to conventional overhead irrigation.
Maintaining your system
You should flush your dripper lines via the line end fittings approximately every six months to release any debris that may have found its way into the system and is not already flushed out by any built-in flush valves. If you folded over the piping with tape or wire, simply remove the tape or wire, unfold the pipe and run the water through.
To clean the filter, shut off the mains water supply, unscrew the filter body, take out the disc element and rinse under clean water. Wash out the disc body, replace the disc filter and screw the filter body back on, and switch on the mains.
The benefits of drip irrigation
It does not require high water pressure to operate. It is a low volume irrigation system, so in areas where municipal water pressure is low, you can still water your garden effectively and efficiently.
It is cost-effective as it uses about 30-50% less water than conventional sprinklers.
It is water wise as there is no evaporation from conventional sprayer mist or wind spray, no wastage of water on paved areas and no run-off.
It gives precise and efficient irrigation to plants, with no dry spots due to abundant plant growth sheltering the soil from overhead sprays.
Because foliage remains dry, there is a reduction in fungal diseases on plants.
How to test flow rate
Connect into the main water supply, open the ball valve and let the water run for a few seconds to allow the pressure to stabilise. Place a bucket with a known volume under the open tap and start a stopwatch. When the bucket is full, stop your stopwatch and record the time that it took for the water to fill the bucket. Then calculate the total flow in litres per hour.