It’s why James Herlihy and his wife Cate retrofitted the 687 metre long pivot at their dairy farm Crieve last winter to a variable rate system (VRI).
Precision Irrigation supplied the hardware and the software for the job and now when it passes over drains, troughs, gateways and lanes the sprinklers above these areas turn off.
“We also had the soil mapped so the heavier soils get less water than the lighter soils,” James said.
“We’re still getting some bugs out but it’s working well so far. We’re hoping we’ll save about 15% to 20% of the water that we can use elsewhere plus there will be less damage to the laneways and we won’t get water ponding.”
If it works, they’ll retrofit their other three pivots.
James Herlihy is the fifth generation on the farm on the Ranfurly-Patearoa Road, which has been in the family since the 1870s. He said everything had been tried on the land from sheep, bulls and cropping to lamb fattening and dairy grazing until they converted to dairying.
‘At the most we’ve had a pivot not working for five or six days. Usually they get them up and running again pretty quickly.’
Crieve is into its fifth season. It peak milks 780 cows with a variable order sharemilker in charge. Nearby Hamiltons peak milks 820 cows and is in its third season with a lower-order sharemilker. Last year Crieve achieved 1464kg milksolids (MS)/hectare and Hamiltons 1362kg MS/ha.
The farm is on the Maniototo East Side Irrigation Scheme which takes water from the nearby Upper Taieri River and then from the Loganburn Reservoir when river flows drop.
The farms also have private water rights from the Sowburn and Pigburn creeks.
When the three pivots on Hamiltons and the one on Crieve are operating, along with the K-lines, 230 litres/second are being poured on the combined 500ha of dairy platform.
On the East Side (there is also a West Side), there are 14 irrigators involved in the scheme, some dairy, the rest sheep and beef using the water on a 21-day roster. Water can’t be carried forward if not used in that period.
“We use every last bit of it,” James said. “It gets to the mid-30s in the summer here and in winter it’s down to maybe minus five, minus ten at times. We don’t grow anything in the winter so we have to grow it in summer.”
The 687 metre long pivot, fitted with a variable rate system, at Crieve Dairy in the Maniototo.
On Crieve it costs about $7000/year for water rates and another $100/ha/year for power, because the water arrives at partial pressure in a 1km long gravity feed pipeline. It works out to be 8.5c/kg MS on farm working expenses of $4.20/kg MS.
Last autumn those on the scheme paid for the Loganburn spillway to be raised so 11 million extra cubic metres of storage could be held in the reservoir. With the dam full, the scheme has about two years of water in reserve.
On the farm, the Herlihys spent $17,000 this year drilling for water on the property but gave up at 170m after snapping the casing.
“We used three different diviners and we did find water but it was in sand, we couldn’t get it out. There are no gravels down there.”
Instead they’re building 5.2km of pipeline to supply pivots to be built on the support area ready for spring 2015 with four other neighbours who will also benefit from the water.
“It’s water we’re using inefficiently, through border dyke irrigation. When we don’t irrigate nothing grows, it just brown so we need to use all the water we can get in the best way. We’re also investing in a storage pond so when it does rain rostered water doesn’t go to waste.”
The pivots start turning in early October and stop about April.
“We can’t start any earlier or keep going later. The trouble is it’s too cold and the water lowers the ground temperature even further. We can handle hot and dry here really well but we don’t do cold and dry. If we have the pivots going past April we can end up making snow.”
They are usually turned off when it does rain.
“I don’t like mud and a lot of the land was once swamp so it can change really quickly. We like to have a bank of soil moisture there before the nor’westers start as the evapotranspiration can be higher than what we are putting on but if we get heavy rain around Christmas and New Year, which we sometimes do, we turn everything off.”
There are no grain feeders in the dairy and no palm kernel in troughs outside so the farms rely solely on grass and crops grown under the irrigation. About a third of silage/balage is made on the platforms and the rest on the support ground which is on the edges.
Fodder beet, grown on the platforms, is fed in autumn to extend lactation and is being planted for the first time on the wintering blocks.
‘We used three different diviners and we did find water but it was in sand, we couldn’t get it out. There are no gravels down there.’
Although the wind is notorious in the Maniototo, the pivots have never been damaged.
“I’ve seen them bounce but they’ve never flipped. All the damage done to them has been by contractors. Once the post driver on the tractor got left in a paddock. We’ve also had a digger versus pivot moment.
“We’re very lucky. Kirk Irrigation in Waimate installed the pivots and they look after us really well. At the most we’ve had a pivot not working for five or six days. Usually they get them up and running again pretty quickly.”
The occasional flat tyre and worn-out rubber boots between the sections have also caused downtime but usually the pivots steadily go around the farms – the longest taking between 18 and 30 hours to make one rotation depending on how much water is needed.
The Crieve dairy unit is involved in a project with the Otago Regional Council to see how the VRI system affects groundwater quality.
“There is a high water table on Crieve and an extensive network of coil drains. We are hoping that the VRI system will limit the amount of water and nutrient travelling through the subsoils and into the coil.
“We have been testing the water as it departs the farm for a number of years so we have some good baseline data.
“We’re also planting grasses like tall fescue, plantain and festoleum which suit dry conditions plus take up more nutrients. We also only put on about 150 units of nitrogen a year.”
As well as keeping an eye on the pivots, James is always watching the weather forecast.
“They keep predicting rain at the moment but it never comes. I think it’s forgotten how to rain.”
Key points
Owners: James and Cate Herlihy
Location: Maniototo, Central Otago
Area: Crieve 235 hectares, Hamiltons 270ha and 600ha support area
Herd: Crieve 780 crossbred, BW 108/45, PW 131/61, Hamiltons 820 crossbred, BW 84, PW 104
Planned start of calving: August 5
Production: 2013-2014 season Crieve 344,060kg MS, Hamiltons 367,821kg MS
