Thursday, March 28, 2024

Design 56…and counting

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Mangatawhiri dairy farmer Rob Lyons and engineer Brook Evans joke that they are already up to design number 56 with the effluent system that’s recently been installed on the 356 hectare south Auckland farm.
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“We looked at what we wanted to do and saw it was a chance to do something special,” Lyons told a group of 25 farmers, environmental specialists and system design companies on a DairyNZ tour of effluent storage and separation options in mid-November.

He’s targeting production of 180,000kg milksolids this season, running a DairyNZ system two or three operation, growing 17.5ha of maize for silage and importing large quantities of chicken manure for fertiliser.

He started to plan to update his old 20-aside dairy 12 months ago and found a lot of the decisions involved in upgrading to a 50-bail rotary with in-dairy feeding quite easy.

“But the effluent treatment system took the longest time,” he said.

“I was still making small changes four months ago. It’s an evolving process and I haven’t finished yet.”

‘If the tank overflows the water goes back to the sump. And because it’s got an open top if there’s too much sediment it can just be dug out.’

Evans, from Williams Engineering, has been with him every step of the way on the project for which there was a budget of $105,000. The system itself came in at about $70,000, an electrician’s work at $10,000 and digger time at about $20,000 for the ponds.

“I’m happy to have just squeaked in under budget,” Lyons said.

Previously there’d been a two-pond system with effluent pumped from the second pond every 10 days or so to be spread by travelling irrigator. But with the new 700m2 yard and connected feedpad catering for his herd of 470 cows he had to think about not only present requirements but those in the future.

He found a lot of useful information about the different effluent treatment options at this year’s effluent field day at Mystery Creek.

“I didn’t want the effluent system close to the dairy,” he said.

“And I was advised not to go for a contained system otherwise I would end up cutting the top of the tank out because of the build-up of sediment.”

He was also firmly against anything which was too complicated or required specific mechanical knowledge. He’s using only one travelling irrigator, with a 90mm diameter pipe which can spread 25,000 litres an hour up to 1.2km away from the dairy.

“That’s enough for here but I will need to get more,” he said.

“I’ve got a decent couple of guys working for me but I felt I had to have the system as simple as possible. They just keep moving the irrigator every day then push a button.”

Another factor in his planning was the purchase of a piggery built in the 1970s on an adjoining piece of land, which has now been converted into a 60m by 30m loafing barn. The cows can lie on the woodchip bedding if they want to, with this being periodically removed and stacked nearby. Once it breaks down into compost it can be applied back on to paddocks where maize will be grown.

“I’m quite excited about it because as a wintering system it will tick all the boxes,” Lyons said.

“And there’s a product we can do something with.”

The piggery already had a three-pond effluent system in place which has now been reduced to two, along with a pre-cast sump and Yardmaster pump which is still running well.

“It was a mission clearing out the ponds,” he said.

“The effluent looked like oil and stank, and was too thick for the pipes so we had to tractor and trailer it out.”

But he was fortunate in having a large area of land he doesn’t milk off, where it could go. And in further good news inspection of the clay linings on the ponds showed they were able to be tested to standard so new linings weren’t required. Natural drainage from the barn and its yard means any liquid effluent will end up in the ponds, an important element of what is a closed system.

‘I was still making small changes four months ago. It’s an evolving process and I haven’t finished yet.’

While rainwater collected from the dairy roof is used for stock water requirements, yard water flows to a stone trap then a 73,000 litre sump with two pumps. From here it can either be irrigated daily on to almost 100ha covered by travelling irrigator or if application isn’t permitted it can be pumped to the ponds for storage until the timing is right. The second pond which has a floating pump hasn’t had to be used yet. Lyons also hasn’t needed to think about what he might need to do to alleviate any crusting problem but concedes he might need to add a stirrer in the future.

Internal dairy water, or grey water, goes into a concrete tank for yard washing with Lyons still using a yard scraper as well.

“It’s a never-fail system,” he said.

“If the tank overflows the water goes back to the sump. And because it’s got an open top if there’s too much sediment it can just be dug out.”

The filter has become a bit clogged with dirt brought into the dairy by the cows so this is one area he’s thinking about changing slightly with a tap soon to be added so grey water can be diverted direct to the stone trap and sump if that’s required. And already he has plans for the future involving another raceway coming in and out of the dairy for better cow flow. There’s also the prospect of putting in an irrigation line across the nearby river, for effluent application on a larger part of the 180ha milking platform which is all GPS’d for grazing.

“It’s fantastic stuff,” he said.

While some dairy functions are computerised there’s no hook-up to soil monitoring yet.

“Perhaps it’s a good idea in the future when the payout changes.”

Also in Lyons future’ planning is the idea of using woodchip as a filler for a weeping wall, which he believes would remove water impurities.

All in the planning

Rob Lyons is a good example of a farmer planning his effluent system, DairyNZ south Auckland consulting officer, Jamie Haultain said. Haultain organised the tour of three different farms and their systems.

“He’s made plan after plan after plan,” he said.

“And it’s really good to see that he’s using different resources throughout the farm.”

This was a better way to look at things rather than just bulk loading effluent all in one area.

In other advice to farmers he said they should think ahead when talking to a designer about putting a new effluent plan together. System designs needed to fit with any possible changes to the farm system such as increased herd numbers, building a feedpad or new management.

There’s no one size fit all design so take ideas from neighbours and friends before making the final decision. Avoid salespeople who claim their products will fix all your problems.

Building a new system doesn’t ensure compliance with regional rules or supply agreements. Staff need to be trained regularly, with fail-safes as final back-up protection against accidents.

A list of accredited companies can be found at www.effluentaccreditation.co.nz.

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