NZ Farmer - Irrigation water flows at Sheffield as new scheme starts

If Central Canterbury arable farmer Damon Summerfield is acting like an expectant farmer it's no surprise. This "baby" has been 10 years in the making.

He's even talking about a christening which is apt when the "baby" is irrigation water as part of the Central Plains Water community scheme.

Water is due to start flowing onto his Sheffield farm during Canterbury show week and he's itching to start this new chapter in his farming career. In expectation of its arrival, Damon and his wife Judith's farm has been turned into a blank canvas. All internal fences have been removed, underground pipes laid and three centre pivot irrigators installed.

Stage 2 of the Central Plains Water irrigation scheme will use 23 kilometres of large diameter 2.5 metre pipe, instead of continuing the open canal, so that all infrastructure will be buried.

"I've wanted this for 10 years," says Summerfield, a CPW director and shareholder. "I thought that to be an irrigated farmer I would have to move away and I didn't want to. It's a great spot to live." While inland from Darfield, it is still reasonably close to Christchurch, where the three Summerfield children attend high school.

Overnight, the 225 hectare mixed cropping property will go from dryland to having 185ha irrigated. "We had no irrigation before. Just one well for the house. That's it. I don't know what it's going to mean. I've got a lot to learn."

About 30 farms are part of the $40 million Sheffield scheme, which covers 4300ha. The scheme is starting with only 5 per cent, or 200 shares – equivalent to 200ha – unsold. As the Sheffield district is higher up the plains than the main CPW Stage 1 and 2 developments it was decided to build it separately, with its own intake and storage dam. It uses about 37km of pipeline and contains seven pump stations supplied from a new two million cubic metre storage reservoir next to SH73 at Sheffield.

Some existing irrigators have joined the scheme, previously supplied from the river or groundwater. "They will now have pressurised water at the gate. Ten years ago there was no irrigation in this area."

Until now, Summerfield says he had not attempted to develop irrigation because of the big depths farmers had to drill to source groundwater in the district. "Certainly people have drilled 150 metres for water, at a cost of around $100,000. We decided CPW was a better investment."

While many years in the planning, construction was surprisingly quick, with the entire scheme, including the Waimakariri River intake, storage reservoir, pump stations and piping, all completed this year.

During the wettest winter in years, more than 5km of piping was laid in trenches across the Summerfield farm, 3km by CPW and 2.5km of their own mainline. "Every single fence has gone, even some boundary fences for a while. None of the fencelines will be the same, they will all be moved to accommodate pivots." The merging of multiple paddocks meant a lot of paperwork to assimilate cropping histories into the new farm layout.

While Summerfield plans to continue arable farming, he expects to double his production through better yields, double-cropping and the ability to grow a bigger range of high-value crops. For about the last 10 years the farm has been 100 per cent cropped in summer, with stock bought in over winter, mainly lambs for finishing. Until now he has grown perennial ryegrass, peas, ryecorn, barley and some wheat. Without irrigation, cereal yields have varied from 3 tonne/ha to 7 tonne/ha, depending on the season. "Last year I doubled my yield and I hope to double it again this year," he says.

"The wet spring has set up crops well, but the farm always looks good this time of the year. It's what happens in November and December that dictates my yield. It can dry out very quickly. We are only two weeks away from a drought.

"I have great hopes that this district could have a niche product. We have a higher altitude, a cold winter and a large harvesting window with the hot, dry northwest winds."

Despite living within sight of Fonterra's Darfield dairy factory, Summerfield believes the district will remain predominantly arable. He knows of one dairy conversion last year and two sheep farms converting to dairy with the arrival of water. "But I can't think of any cropping farmers converting because of the scheme."

The district has good soils which improve further up the plains. "It is ideally suited for cropping with water."

This year the couple are growing the same crops as usual, but from now on they will have a more diverse cropping rotation. This includes specialist hybrid vegetable seed crops, with the Summerfields growing 4ha of mustard for seed multiplication for the first time this season.

Previously, all cereals were autumn-sown, but this will also change. "I could never grow a spring-sown cereal. It's too risky as a dryland farmer." He will now be able to grow more crops in spring, allowing him to double-crop in the same season.

The fully-lined storage reservoir, covering 30ha and 10m high, can hold two weeks of storage for the scheme. "If we chose, we can use half the water for twice the time. As an arable farmer I can save water to finish a high-value crop."

As well as pumping from the Waimakariri River intake, gravity-fed water is being supplied to the storage reservoir via the existing Selwyn District Council stockwater network from the Kowai River.

"Shareholders like to be part of a scheme that they own." They also want to enhance the environment and have no wish to waste water or nutrients, despite what some environmentalists may think, he says. Farmers need to supply a nutrient budget and farm environment plan before receiving water and on an ongoing basis.

"A lot of shareholders have done it for the legacy it provides the district and for the long-term benefits to the community," Summerfield says.

CPW managing director Derek Crombie says the Sheffield water scheme contract was signed in December last year and the main contractor, Fulton Hogan, started work on January 9. "It's been an intense project to get that amount of work done in 10 months."

The storage reservoir began filling in early November and will be progressively filled over summer as water is available. With the storage reservoir, the scheme will have a high reliability of 95 to 98 per cent.

Sheffield shareholders paid $3000 a share of equity, with the remainder of the construction funded by bank debt. Farmers then pay an annual charge of about $700 a share, with one share averaging a hectare.

In comparison the capital charge for CPW stage one shareholders was $1750 a share in 2014, with annual charges of almost $900 a share a year. "So it was lower capital, but higher debt," Crombie says. "The Sheffield farmers were able to put more equity up front."