Centre Pivot Wins Over Solid Set Irrigation

A Malanda dairy has implemented an irrigation energy management opportunity from the energy audit report they received through the Energy Savers Plus Program Extension. Through the program the business received a dairy shed energy audit, carried out by AgVet Energy, as well as an irrigation energy audit, completed by The Energy Guys, both engaged by QDO.

In the past the farm had always implemented solid set irrigation systems and twelve sections of solid set irrigate a 28Ha area. The energy audit found there would be more benefits for the business to implement a center pivot for their next irrigation project.

Installing a center pivot irrigator with 150mm PVC mainline covering an area of approximately 11.2ha has increased the farm’s irrigatable area and pasture production potential as well as being water, energy and labour efficient.

eastAUSmilk Project Officer, Jade Chan, and I visited the site and conducted a performance test on the irrigation to evaluate the actual energy savings and outcomes achieved since implementing a recommendation from the energy audit.

The main saving for the business has been the increase in irrigatable area and improved uniformity of water application. Across the 11.2Ha an increased in pasture production of around 23 tonnes of dry matter annually could be expected.

Another saving for the business has been labour. A centre pivot requires significantly less labour to setup and operate in comparison to a solid set system, where the addition of several valves that require manual opening and shutting increases the labour requirements.

To apply 75ML over 11.2ha, a solid set system would run for 772 hours/year at the estimated flow of 27LPS and with 12 hour runs this is equivalent to 64 set ups. A solid set station can take approximately a half hour to set up amounting to 32 hours per year.

The center pivot system allows remote control and irrigation scheduling. Minimal time is required to set up and switch on or off. Total labour savings over the course of the year would be $2 560 costed at $80 per hour.

The pivot will also save 1,647kWh/year based on 75ML annual application in comparison to a solid set system saving $378.80/year.

The centre pivot can apply irrigation to the paddock(s) with less head requirement, drawing less energy demand from the pump. The proposed solid set irrigation was estimated to have a duty point for the bore pump of 27LPS at 117m total head, whereas the centre pivot will be performing at 29LPS at 107m total head.

The total expenditure for the business to implement the upgrades was just under $94,000. Valuing the increased pasture production at $5,000, plus the labour saving of $2,560 and $379 for electricity savings the calculated payback period of this investment is 11.8 years with a return on investment of 8.4%.

Torie Harrison – eastAUSmilk Project Officer