PHOTO: LINDSAY CORPORATION
IMAGE: CAROLYN HEDLEY
IMAGE: CAROLYN HEDLEY
WATER TECHNOLOGY ▶▶▶ GROWER POINTS ON VRI
▶ 30% water savings on variable soils/topography ▶ Yield, trafficability and quality gains add to returns ▶ Reduces run-off/leaching – i.e. environmental – risks ▶ Costs circa NZ$ 110/m (€ 64) of pivot or lateral fitted ▶ Management enthusiasm essential or use may lapse ▶ Hardware proven but better crop sensing and software needed
New Zealand’s Landcare Research institute also monitors the first use of Lindsay’s FieldNET Advisor software in New Zealand’s 2017/18 summer to see how well the model predicts actual soil moisture and crop canopy temperature measurements.
World record growers also adopted VRI World record holders for wheat yield, Eric and Maxine Watson, from Ashburton, were also in the vanguard of New Zealand growers to adopt the technology, though the world re- cord crop was grown under one of two irriga- tors they have yet to fit with VRI. “We’ve done seven out of nine,” Maxine told Future Farmer magazine. She says they’re using 20% less wa- ter as a result, with associated power savings and yield increases, particularly on areas where overlaps or different crops under one irrigator caused over- and/or under-watering. Hew Dalrymple, a North Island cereal and veg grower, echoes those water savings. He in- stalled his first VRI-equipped pivot in 2009 and now has it on 13 of his 31 irrigators cover- ing 2,000 ha near Bulls. “Mechanically they
seem very reliable but the software’s where they vary most,” he comments, pointing out Valley Irrigation, as well as Lindsay Corpora- tion and a couple of other companies now offer VRI systems in New Zealand. “It’s the shoulder seasons or a wet summer when it’s most value. In a hot dry summer everything’s flat out.”
Need for better industry support Andrew Curtis, chief executive of Irrigation New Zealand (INZ), a voluntary, farmer-fund- ed representative body for water users, says there’s no recent data on areas under VRI, but he estimates between one in five and one in six (17-20%) of all new pivots in New Zealand are fitted with it. That’s likely to continue to grow, provided a current “crossroads” for the technology can be negotiated. “There’s got to be better industry support for it after initial set-up. We’ve found about a third of the sys- tems are not being used.” Frequently that’s be- cause management of the farm has changed and the newcomer hasn’t got to grips with the system. INZ is working to rectify that
because it estimates half of the area likely to end up under pivot irrigation in New Zealand has sufficient variability in soil, topography and/or crop for VRI to be commercially and environmentally beneficial. Currently just over 45% of New Zealand’s 780,000 ha that’s irrigated is under pivots but that’s predicted to grow to 60% of what will likely be 850,000 ha watered by 2023, suggest- ing several hundreds of thousands of hectares could be under VRI there before too long. “Development of better software and decision support tools for precision VRI will be key,” says Carolyn Hedley, of New Zealand’s Landcare Research institute, who has led much of the independent analysis of VRI instalments in New Zealand to date. That includes monitoring the first use of Lindsay’s FieldNET Advisor soft- ware in New Zealand’s 2017/18 summer to see how well the model predicts actual soil mois- ture and crop canopy temperature measure- ments. “To date it is performing well,” says Hed- ley. The aim is also to determine what type of sensors will best inform such model-based VRI scheduling software, she adds.
A fundamental concept that needs to be understood – at the start – is that where different soils occur side by side in the landscape they are likely to require different irrigation schedules.
22 ▶ FUTURE FARMING | 25 May 2018
The soils of a 23 ha Ohakune potato field that were investigated guid- ed by the EM survey, had very different profiles and water holding characteristics.
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