Water use and pumping costs reduced with innovative drip irrigation system
Updating their drip irrigation system has saved Nicholson River Winery 66 per cent of their water and electricity use. “Our vineyard is a work in progress, however there are indications that water use has been reduced from three megalitres/hectare/year to one megalitre/hectare/year”. The property has been producing wine for almost 30 years and relies on irrigation to help supplement the variable 663 mm rainfall at Nicholson, in East Gippsland.
Jeff Paterson, Peter O’Keeffe and Ken Eckersley of the Nicholson River Winery won first prize in the 2010 Southern Rural Water Waterwise award for groundwater users for their work in installing a new generation of drip irrigation. The judges commended it as being highly adaptable to other forms of horticulture. The new irrigation system is easy to install and comprises readily available components.
The Nicholson River Winery has been using trickle irrigation for almost 30 years. The first vines relied on rainfall and established a deep root system. “They are still producing the best quality fruit on the property.”
Over time as rain became scarcer, surface drip irrigation was installed. The new vines grew but under performed . Extended drought coupled with competition from summer grasses and under optimal watering created plants with limited root development. These plants were also often prone to disease.
This led Peter and Jeff to suggest to Ken using conventional drippers and PVC pipe and has since developed into what they call the Nicholson Irrigation System (NIS). This is a system that delivers water directly to the plants roots, is long lasting with leaks and blockages easy to find and fix. “We wanted a system for the long-term that was accessible, flexible and transparent”.
The NIS combines the transparency of surface drip irrigation and the water savings through reduced evaporation and competition from summer grasses that subsurface irrigation provides. The NIS does this by using 13mm or 19mm irrigation lines with pressure compensating drippers that are located at each vine and drip inside a 40mm PVC pipe.
Installation involves using a post hole drill to dig to a depth of about one metre, loosening the soil below the PVC pipe. This is about half a meter below the end of the PVC pipe, to allow water to freely flow into the soil. Gypsum can be added to clay soils to help improve soil structure during installation and to also help with water penetration. The 60cm PVC pipe is then inserted into the ground with 10cm exposed above ground. The base of the PVC pipe is cut on an angle to reduce blockages during installation or later. See (Diagram 1).
The introduction of the NIS on the property has also been complemented with an extensive network of tensiometres to measure soil moisture. A future plan includes automating the irrigation system with electronic valves and a timing unit, as half an hour to an hour is ample watering time with the NIS system. The original drip irrigation system took six to eight hours per watering.
The main aim for the NIS is to deliver water directly to the plant’s root zone rather than to the ground surface. “Because water is delivered directly to the plant roots, there are reduced losses in evaporation and to competing grasses”. Plant roots are also able to go deeper rather than staying near the surface of the water source. “The PVC pipe directs water to the right place into the root zone where the plant can use it; there is no wastage”.
The NIS also allows a quick response by plants to added fertilisers or fertigation. However, nutrients need to be carefully applied to avoid burning the sensitive roots. The NIS also allows for a variation in dripper rates according to soil types. An unexpected benefit from installing the system is that the PVC pipe has provided a habitat for snails to collect in which can then be killed with baits.
Water-logging may be a problem in some soil types. Installing the PVC pipe with an angled end, drilling the watering holes deeper then the PVC pipe and adding gypsum into the hole can help to increase infiltration rates. The potential impact of water-logging can also be managed by varying the volume of water delivered to each plant by changing the rate at each dripper based on soil type.
The installation of the new system costs more than in line irrigation at about $3.50 -$4.00 per vine and half of this is the labour cost (more to retrofit an existing line irrigation system as more labour is needed). So far the eight hectare vineyard has had half of its 16,000 vines upgraded to receive water through the NIS. “In times of long-term rainfall decline and rising costs it can be the difference between viability and a slowly declining vineyard.”
Jeff, Peter and Ken believe replanting is a great opportunity to reconsider and apply a new way of thinking. “There are huge potential savings to be made. In today’s climate it’s about a quality product which is smart and efficiently produced.”
The new NIS irrigation system makes better use of a limited water resource and introduces a new generation of drip irrigation.
