Trial leaves potential financial, environmental legacy

5 Jul 2018, 8:42 AM

The regional council's long-serving Farm Monitoring Manager has hung up his gumboots; but has left behind a dairy effluent reduction model that could prove to be an impressive environmental and economic legacy.

Dennis Wright retired after 17 years with council, late June, leaving behind a remarkable set of trial results showing it's possible for Northland's dairy farmers to dramatically slash effluent volumes going to treatment/storage ponds.

Over the past four years, trials have been completed on four farms around Northland; one at Brynderwyn, another at Waiotu near Hukerenui, one at Waipapa near Kerikeri and another at Ngararatunua near Ruatangata.

A range of initiatives long promoted by Mr Wright have also helped improve water quality by significantly reducing the farms' water use and associated discharges of treated effluent to water. (A fifth farm included water efficient systems in a new dairy, with good results.)

Collectively the four farms taking part in the trial have reduced the amount of water used in their seasonal dairy operations by roughly 15,000 cubic metres (15 million litres) and have cut the amount of wastewater they generate by almost 16,800 cu m (or 16.8 million litres).

"The two best-performing farms in the trial reduced their water use by roughly half and the others by roughly a third," Mr Wright says. "Data collected at two of the four farms showed that they also managed to cut the effluent volume generated by roughly half."

He says the dairy industry has spent – and continues to spend – many millions of dollars on projects aimed at mitigating adverse environmental effects and improving its image.

Yet the trials had proved with just a few simple and cost-effective changes, it was possible to tackle issues related to water extraction and point source effluent management.

"This not only improves environmental performance, but can result in significant reduction in on-farm operating costs."

Mr Wright says central to the trials has been the use of water meters to measure actual use at different points around the dairy, the installation of more water-efficient cleaning nozzles and diverting as much clean stormwater as practicable away from the treatment ponds.

Other initiatives some farms had introduced had included changing from water to electric-driven yard backing gates and using recycled effluent to clean their dairy yard.

One of those trialling – and impressed by – Mr Wright's system is Ken Finlayson, who milks 780 Friesians on his 300-hectare Ngararatunua dairy farm.

Since moving into a new dairy shed three years ago, he has almost halved his water use, largely though changing nozzles on hoses, the farm dairy bridge and D-gate, by capturing plant wash water and recycling through a yard wash system.

"We're saving about 5.4 million litres of water per dairy season, which equates to usage of about 27 litres per cow per day on average," he says. (Typical standard industry usage is about 70 litres of water per cow per day.)

Mr Finlayson says as well as the obvious environmental benefits – it's much easier to be compliant because you're not handling such large volumes of effluent – the fact he would not need to pay for an additional effluent storage pond was worth about $80,000 to him.

"We also save almost 400 hours we don't need to spend irrigating from a tractor-driven pump and there's about 120 times our irrigator doesn't have to be moved so these equate to some big savings in terms of labour and pumping costs."

Mr Finlayson says while he takes water quality very seriously, his key focus when he built his new dairy shed about three years was to save labour, "but with a few quite minor changes, it's really been quite dramatic in terms of water savings too".

"Water is a scarce resource and it's only going to become more valuable over time."

Mr Wright says as a long-time compliance officer and former dairy industry manager himself, the idea for the effluent reduction project stemmed from his own frustration that co-operative and willing Northland farmers could still find it difficult to comply with their resource consent conditions.

"Regional council staff work closely with dairy farmers and both parties are keen to improve the industry's compliance rates in the region and achieve better environmental and economic outcomes."

While his retirement meant he was now handing the task of managing the monitoring of the region's roughly 900 dairy farms to someone else, he would very much like to see the industry take notice of the trial results and follow the lead set by the council and its farmer trial partners.

“I’ve said many times that on an industry-wide basis, there’s a potential to implement similar measures (especially if applied to new dairies during construction) which will not only enhance environmental performance, but also improve financial results by reducing capital, energy and labour costs.”