Friday, March 29, 2024

Ripping into planting and fencing

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Hikurangi Swamp dairy farmers Graeme and Sharon Gillett and their son Donald, who sharemilks the 600-cow herd, are keen to get started on a Living Waters project.
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About 200m of new fencing and riparian retirement and planting on the north bank of Cole Drain near Riponui, Northland are planned for this autumn, when regular falls of rain will ensure the immediate survival of trees and shrubs.

Out of their own resources the Gilletts would like to go further than the project planting plan. There are 5km of drain bank, on both sides, within the 360ha farm which provide plenty of opportunity. The existing riparian zone needs widening by moving fences out two or three metres, and there are water lines to be buried, weeds to be controlled and sturdy seedlings to be planted.

The $20 million, 10-year joint venture between Fonterra and the Department of Conservation was launched last year to work on five sensitive sites nationwide for dairying’s effects on the environment, particularly water quality. The Northland site has to be the biggest challenge geographically, covering the 640,000ha Kaipara Harbour and its multiple catchments.

Fonterra and the department have decided to begin about as far up the Wairoa River system as it is possible to go in central Northland. The Hikurangi Swamp is home to 38 dairy farms, containing some portion of the desirable heavy peat land subject to regular flooding, among 140 dairy farms in total in the Hikurangi district.

A flood control scheme for the swamp is either side of the serpentine Wairua River, which afterwards becomes the Wairoa and flows westward about 75km to Dargaville and the Kaipara.

The 6500ha swamp scheme, in seven “pockets” with their own banks, floodgates and pumps, is only 1% of the entire Kaipara catchment total, which includes the 95,000ha (at high tide) harbour. It is the largest harbour in the southern hemisphere and a very important source of juvenile fish for the upper west coast of the North Island. Its sand dunes, sea grass, freshwater and estuarine wetland ecosystems are among the rarest in the country.

The Wairoa River, the biggest feeder to the Kaipara Harbour, has long been polluted with mainly sediment run-off and considerably modified with dams, banks and pumps. It also has massive infestations of Manchurian rice grass in the lower reaches.

The Living Water planning team in the north believes water quality restoration has to begin in the drains and streams which are the fifth or sixth level Wairoa/Wairua tributaries in order to rebuild biodiversity with sustainable native species, fish, birds and plants.

They want to complement existing efforts, such as those by Northland Regional Council, Whangarei District Council (WDC), Kaipara District Council, the Integrated Kaipara Harbour Management Group and the Mangakahia River Landcare Group to name just one of the self-help groups of land owners in the catchment.

The Gilletts are keen to include local community involvement in the Living Water project, whereby Hukerenui School would participate in planting and tending.

“It would be good to foster understanding in the community of what is being done by the dairy industry environmentally and to improve the industry’s image,” Graeme said.

Within the Te Mata pocket of the flood control scheme, the Gillett farm doesn’t have the problems with floodwaters that cause lower swamp farms regular headaches like fencing and structural damage and loss of pasture.

“The water comes over our paddocks nearest the drain but doesn’t stay around long,” he said.

“During an hour or two the floodwaters wash out culverts and tracks and hang debris on the fences and then move quickly on towards the Wairua.”

For that reason, as well as the farming benefits of the peat land, they don’t begrudge the WDC targeted rates for management and upkeep of the scheme. Angered by steep rate increases, there is a smaller “united” or concerned ratepayers group of farmers who have alleged mismanagement and wastage by WDC and taken the council to court.

Now more than 40 years old, the scheme’s infrastructure is wearing out and WDC cannot keep up with the maintenance and replacement needs. So the Living Water selection of the Hikurangi Swamp as its starting point for the Kaipara Harbour project is bold and potentially problematic.

The Gillett family has farmed at Riponui for the past decade and in that time the business has developed to System 3, targeting 400kg milksolids/cow this season by supplementing with maize and grass silage and palm kernel and using two Herd Homes. The whole farm is 360ha of which one-third is peat flats and two-thirds rolling hills. The milking platform is 270ha, which includes up to 25ha of maize grown each season.

Graeme said the cows have not had access to the Cole Drain during his time on the farm and there had been some annual spraying of Roundup organised by the WDC, which manages the swamp scheme. But he’s suspended that helicopter spraying, preferring to do his own from an ATV and trailer and targeting the woody weeds like blackberry and gorse.

Cole Drain runs clear most of the time and the freshwater ecologists who have surveyed it say it contains a variety of fish life. The Gilletts don’t have a consent to discharge treated effluent and nor do they want one. They can irrigate up to 80ha with pods and travelling irrigator, up to 1.5km away from the effluent ponds.

Graeme said it was his responsibility to move the irrigation system and determine the days on which it was appropriate to irrigate.

“We have storage for 90-100 days and we watch the rainfall figures for gaps during which soil capacity is right for irrigation.”

The nozzles on the pods can be changed from 7mm to 15mm/hour application rates.

They also have an effluent tanker to pump sludge out of the first pond during summer which is spread around the farm, along with the dry effluent from the HerdHome bunkers. The farm nutrient budget takes full account of the effluent sludge and water returned to pasture.

The Gilletts also look after the drainage system across the peat flats, spraying vegetation and getting in a digger to restore the V shape as the peat moves around.

Dam water is used for farm dairy washdown and although the water does contain algae no contamination of the milk occurs, verified by regular testing by Fonterra.

The farm water supply is all surface water, without any permanent sources, although the Gilletts have tested and drilled.

Consent has been gained for another farm dam but building that has been postponed until spring to minimise the danger of sediment run-off from exposed soil surfaces during the higher winter rainfall months.

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