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WATER
There are many advantages of drip Irrigation which can be summarised as follows :
• Fertiliser and nutrient loss is minimised due to localised application and reduced leaching .
• Water application efficiency is high if managed correctly
• Field levelling is not necessary
• Fields with irregular shapes are easily accommodated
• Recycled non-potable water can be safely used
• Moisture within the root zone can be maintained at field capacity
• Soil type plays a less important role in frequency of irrigation
• Soil erosion is lessened .
• Weed growth is lessened
• Water distribution is highly uniform , controlled by output of each nozzle
• Labour cost is less than other irrigation methods
• Variation in supply can be regulated by regulating the valves and drippers
• Fertigation can easily be included with minimal waste of fertilisers
• Foliage remains dry , reducing the risk of disease
• Usually operated at lower pressure than other types of pressurised irrigation , reducing energy costs
Consider the street trees in the city of Melbourne case study . It is estimated that Melbourne city manages approximately 55,000 trees including 18,000 street trees . The value of Melbourne trees is estimated to be just over half a billion dollars . The trees were subject to significant stress due to low soil moisture caused by 10 years of drought , reduced rainfall effectiveness , reduced supplementary water and the reduced uptake of water by damaged roots . The city set a strategy to change water sources and improve irrigation efficiency by adopting various drip irrigation systems , watering trench , tanker watering , water barriers , soil water injection , mulching and modification of irrigation schedules . This has achieved over 60 % reduction in water use in parks , gardens and open space .
Other successful case studies include Port Augusta in South Australia which now irrigates more than 48K m2 of landscaped area using a drip irrigation system . This technique has helped reduce water usage by 30 %, along with using waste-water , achieving a total of 50 % water saving .
Another avenue for utilising drip irrigation by local governments is the use of subsurface drip irrigation in sports field irrigation . The city of Glen Eira in VIC after raising the water restriction to level 3 allowed only one in every four sports field to be irrigated . These restrictions have pushed the city council to host a research studying the benefits of sub-surface drip irrigation over overhead sprinklers in sports fields . Among the main benefits identified :
• Watering efficiency of up to 99 % - sub-surface drip systems radiate water throughout the soil profile , delivering water directly to the plant root zone
• Water savings of up to 50 % in comparison to volume required for spray irrigation
• Ready for Recycled water – The ability to apply water sub-surface provides an opportunity to use alternative water resources ( i . e . recycled water , storm-water , etc .) and minimises the requirement for potable water
• No overspray , therefore , less staining , slippery surfaces and wasted water
• Less vandalism of watering systems as they are predominantly underground
• Even water distribution throughout playing field , no pooling and no sprinkler head to trip over
• Reduced weed germination
• Reduced compaction of playing field
• The ability to irrigate while people are playing on the surface
• Fertigation through the drip tube is making it easy to apply and ensuring less opportunity for chemical contact with the general public
GOVLINK » ISSUE 3 2016