Wa­ter gives veges the green light

Veg­etable pro­duc­tion is set to ex­pand in cen­tral Can­ter­bury fol­low­ing the com­ple­tion of the se­cond and fi­nal stage of the mas­sive Cen­tral Plains Wa­ter (CPW) ir­ri­gation scheme.

NZ Grower - - Your Levy At Work - By Heather Chalmers

At a cost of $450 mil­lion, CPW is prob­a­bly New Zealand's big­gest pri­vately funded in­fras­truc­ture project, ir­ri­gat­ing al­most 50,000 hectares of the up­per cen­tral Can­ter­bury plains be­tween the Rakaia and Waimakariri Rivers. CPW also es­ti­mates that farm­ers have in­vested a fur­ther $187m on ir­ri­gation.

While other ir­ri­gation schemes such as Hu­runui in North Can­ter­bury and Hunter Downs south of Timaru, strug­gled to get suf­fi­cient farmer fund­ing to pro­ceed and Waimea Ir­ri­gation, Nel­son, is look­ing to cover bud­get blowouts, CPW has de­liv­ered its scheme on time and on bud­get. Stage two ser­vices 20,000ha, sup­ply­ing pres­surised wa­ter to far­m­gates. This is in ad­di­tion to the 23,000ha ir­ri­gated in stage one and 4300ha in a Sh­effield scheme on the up­per plains.

Pota­toes NZ chair­man, Stu­art Wright, whose farm re­ceived wa­ter from CPW in Novem­ber last year as part of the Sh­effield scheme, said there were a lot of op­por­tu­ni­ties to grow crops on bet­ter soils within the scheme which were pre­vi­ously non-ir­ri­gated. De­vel­op­ment of crops was likely to gen­er­ate new food pro­cess­ing in­dus­tries in nearby cen­tres such as Rolle­ston and Christchurch. And ex­ports could go di­rectly to Asia through Christchurch In­ter­na­tional Air­port. “Al­ready we have sev­eral North Is­land grow­ers with a pres­ence in Mid Can­ter­bury and I can only see this con­tin­u­ing, es­pe­cially as they come un­der pres­sure from pop­u­la­tion growth and ur­ban sprawl around Auckland,” he said.

“With wa­ter, there are not many places bet­ter to grow crops than Can­ter­bury.”

Darfield arable farm­ers Pe­ter and Gretchen Red­fern joined CPW to wa­ter a dry­land block and re­duce re­liance on their ex­ist­ing ground­wa­ter take. Now wa­ter­ing 410ha, they pre­vi­ously ir­ri­gated 260ha, “but were al­ways un­der-watered and look­ing for the next shower of rain”.

The Red­fern fam­ily has farmed the prop­erty for 120 years, with their son and daugh­ter-in-law Hamish and Janet the next gen­er­a­tion to take up the ba­ton.

“A lot of new ir­ri­ga­tors will find the cost chal­leng­ing, but there will be no more op­por­tu­ni­ties to ac­quire wa­ter,” Pe­ter said.

“For this rea­son farm­ers had to com­mit to it and see where it takes them in the fu­ture. Can­ter­bury could be grow­ing

fresh veg­eta­bles for the world. Peo­ple who don’t nec­es­sar­ily sup­port ir­ri­gation have to re­alise that if we don’t con­tinue to lift pro­duc­tion and keep the price of food at a rea­son­able cost, where is the world’s food go­ing to come from?

“To­day’s ir­ri­gation ap­plies such small vol­umes of wa­ter more of­ten, that you never waste a rain­fall. The ir­ri­gation tech­nol­ogy to­day and soil mois­ture probes do a lot of keep the mois­ture level where it should be.

“A cen­tre pivot can go around 100ha in a day and ap­ply 4.5mm. So you are never get­ting the soil to a point where it won’t ab­sorb rain. Ear­lier ir­ri­ga­tors took five to six days to go around the same area, putting on 25 to 30mm.”

The Re­ferns grow veg­etable seed crops for ex­port, in­clud­ing radish, car­rot, corn salad and Chi­nese cab­bage. Other seed crops are bar­ley, rye­grass, white and red clover and cocks­foot.

“You can’t grow those crops with­out ir­ri­gation. Hav­ing wa­ter avail­able at the right time is key,” Pe­ter said.

To date, fears that CPW will lead to wall-to-wall dairy farms on the plains haven't even­tu­ated, with only a hand­ful of dairy con­ver­sions. Rel­a­tively flat dairy pay­out prices, as well as En­vi­ron­ment Can­ter­bury re­duc­ing lim­its on farm ni­tro­gen losses are likely to keep a lid on dairy de­vel­op­ment. How­ever, every­body ac­knowl­edges that it’s ex­pen­sive wa­ter and farm­ers will have to make changes and be­come more in­ten­sive to make it pay.

The con­cept be­hind CPW was first in­tro­duced as far back as 1999, but it wasn’t un­til 2010 that re­source con­sents were granted. Wa­ter for CPW stages one and two is sourced from the Rakaia River, while a 4300ha se­condary scheme at Sh­effield takes wa­ter from the Waimakariri River. CPW’s an­nual take equates to one sin­gle day of the Rakaia River flow, or two per­cent.

Af­ter ini­tial plans for a wa­ter stor­age reser­voir in the Wa­iani­waniwa Val­ley in­land from Coal­gate were re­jected, CPW suc­cess­fully ne­go­ti­ated with Trust­power to use stored wa­ter in Lake Co­leridge. Ear­lier plans for a 56 kilo­me­tre head­race canal to run along the foothills be­tween the Rakaia and Waimakariri Rivers were aban­doned in favour of bury­ing all in­fras­truc­ture in stage two. In­stead stage two uses 21km of buried large di­am­e­ter 2.5 me­tre pipe for its cen­tral spine, as well as 180km of distri­bu­tion pipework. Even now there is lit­tle to see of the scheme, apart from on-farm ir­ri­ga­tors. >

CPW stage two has 150 share­hold­ers cov­er­ing 200 farms, and pay­ing $2050 for each con­struc­tion share, equiv­a­lent to a hectare watered. In ad­di­tion, farm­ers pay an av­er­age wa­ter charge of about $800/ha, made up of $600 of debt and $200 of op­er­at­ing costs. The debt would be paid off over a 40-year term. In stage two, about half of its farmer-share­hold­ers were ex­ist­ing ir­ri­ga­tors, who will switch from ground­wa­ter to sur­face wa­ter from the scheme, with the re­main­ing half new ir­ri­gation.

The dis­trict is pre­dom­i­nantly mixed crop­ping and sheep and beef, with many prop­er­ties farmed by the same fam­i­lies for more than a cen­tury. Arable re­search showed that an av­er­age dif­fer­ence in ce­real yields of four tonnes a hectare over 10 years be­tween ir­ri­gated and non-ir­ri­gated crops would cover the cost of ir­ri­gation. CPW fig­ures show that ir­ri­gated farm­land, on av­er­age, gen­er­ates three times the pro­duc­tion of an equiv­a­lent area farmed un­der dry-land sys­tems. Stud­ies on the eco­nomic ef­fect of ir­ri­gated agri­cul­ture show that one third of the wealth and em­ploy­ment cre­ated from ir­ri­gation oc­curs on­farm, with the other two thirds spread through the ru­ral and city com­mu­ni­ties.

CPW gen­eral man­ager, Derek Crom­bie, said farmer-share­hold­ers are re­quired to meet good farm man­age­ment stan­dards and com­plete a farm en­vi­ron­men­tal plan.

“They can't get wa­ter un­til they have one.”

By 2022, within four years of re­ceiv­ing CPW stage-two wa­ter, dairy farms are ex­pected to re­duce their ni­tro­gen/ ni­trate loss by 30 per­cent and dairy sup­port by 22 per­cent. Ir­ri­gated sheep and beef farm­ers must re­duce by five per­cent, arable by seven per­cent and veg­etable grow­ers by five per­cent.

As CPW was in ECan's Sel­wyn-Wai­hora wa­ter catch­ment, des­ig­nated as over­al­lo­cated for wa­ter, the scheme was re­duc­ing pres­sure on ground­wa­ter re­sources. Ground­wa­ter con­sents in the dis­trict to­talled 100 mil­lion cu­bic me­tres, but by 2016-17 only 15 cu­bic m was ac­tu­ally be­ing used.

"So we are con­trol­ling nu­tri­ents on the one side and re­duc­ing ground­wa­ter use on the other," Derek said.

STU­ART WRIGHT ◀ Pota­toes NZ chair­man, Stu­art Wright, said there are a lot of op­por­tu­ni­ties to grow crops on bet­ter soils within the scheme which were pre­vi­ously non-ir­ri­gated.

Hav­ing wa­ter avail­able at the right time is key.PE­TER RED­FERN

▴ Stage two of the Cen­tral Plains Wa­ter ir­ri­gation scheme uses 21km of large di­am­e­ter pipe, rather than an open canal, so that all in­fras­truc­ture is buried.

▴ The main wa­ter chan­nel goes from an open canal to a buried pipe in stage two of the Cen­tral Plains Wa­ter ir­ri­gation scheme.

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