Futureproof: in a pond

19:36, May 30 2012

Taranaki's prize-winning effluent storage pond replaces a system that demanded virtually the fulltime attention of Pungarehu sharemilker Dan Merritt.

After working as project manager on the construction of the pond on the 200ha Pungarehu farm of Ken and Christine Sole, now of Kerikeri, Coastal Agri Services' effluent adviser Alex Scott entered it in DairyNZ's Keep it Low promotion.

The Pungarehu pond was one of two winners of the nationwide competition, for which the prize was a barbecue - held on the farm last week - with former All Black Richard Loe.

Mr Merritt and wife Shelley are in their first season as variable order sharemilkers for the Soles and milked 530 cows this season. Next season they will milk another 40.

Fonterra sustainable dairy adviser Kevin Taylor said before the new pond was established, the farm's effluent flowed into a 20,000 litre sump, the contents of which had to be irrigated every day.

"With the number of cows on the farm, the system was struggling to keep up. It was hard to manage and the sharemilkers were at the mercy of Mother Nature and wondering whether the (Taranaki Regional) Council would turn up to inspect it."


After a Fonterra visit last year, the farmer was told to install a better effluent storage system.

The new 54sqm pond, which is 2.5m deep, with a capacity of six million litres, provided good options for nutrient management on the farm. When conditions were suitable, its contents could be spray-irrigated daily at a 10mm application depth, he said.

The location of the pond was suitable if a new cowshed was built on the farm in future.

"The pond futureproofs the farm - it's not a band-aid. The system will last a long, long time because it has copious amounts of storage. But it still needs to be managed."

Mr Merritt said the previous effluent system was a mess. "The effluent was running us - every morning and every afternoon we had to pump out thick effluent from the tank, even when it was raining, to ensure there was no overflow. It was pretty much a fulltime job.

"We tried to maintain it as well as we could. Then Fonterra said, 'Enough's enough' and told Ken to fix it."

Mr Merritt said the new pond - half the size of a rugby field - had 90 days of storage, but he still irrigated the effluent as often as possible - "when the sun shines, when it's cloudy, every chance I get.

"Now we have a nice diluted fertiliser. It's an asset instead of a burden."

He applies the effluent over a 25ha block of the farm through a permanent irrigation system. "We graze a paddock and wait until the cover reaches 1800kg dry matter/hectare, then we apply it."

Good management ensured the pond level could be kept low for contingencies, such as extended periods of wet weather when the ground was too saturated for irrigation.

The farm also has its own irrigation system over 80ha of the farm, using water from the Kapoaiaia Stream. "But it kept raining this summer and we didn't use it at all," said Mr Merritt.

The couple's production for the 2011-12 season is expected to be 170,000kg milksolids (MS) and they are targeting 180,000kg in the new season.

Mr Scott said a Firestone EPDM liner, which was UV-resistant and flexible, was used to line the pond because finding clay suitable for pond construction was difficult in coastal Taranaki.

Provided by Hawke's Bay company Irri-Max, the liner has a 20-year product and workmanship guarantee.

Drainage was installed 600mm below the pond's floor and an underlay, with gas drainage, allows methane gas to escape. The pond has an 11kw Reid and Harrison stirrer with a right-angle drive that prevents the liner lifting and a 7.5kw Reid and Harrison pump with a capacity of 20,000-litres an hour. The pond will never need emptying.

Taranaki Regional Council compliance manager Bruce Pope said farmers with small sumps on their properties had trouble all year round complying with their resource consents. An effluent pond built to specification worked out by the council's pond size calculator ensured resource consent compliance.

It also provided the most benefits because using the effluent as fertiliser helped recover the cost of the effluent system.

Mr Merritt has been farming for 13 years and sees himself as a caretaker of the land. The couple decided to move from Whangarei to Taranaki for the better farming opportunities here. They're getting used to the cooler temperatures and, as a keen surfer, Mr Merritt is enjoying being able to surf -but just in summer - at the nearby renowned Stent Rd surfbreak.

Mrs Merritt said the couple were excited at the win. "It's good to be doing the right thing by the environment. We love water and we love fishing."

Competition judge, DairyNZ's development project manager for effluent, Theresa Wilson, said many examples of well-managed and constructed ponds were presented.

The competition was run to encourage farmers to keep as much effluent storage free as possible.

Taranaki Daily News