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Improving Lake Rotorua

Land & Water

Biological farming will be part of the arsenal used in Rotorua to combat farm nutrient losses, and will be in use sooner rather than later.

Rotorua District Council Mayor Steve Chadwick told delegates at the second national conference on biological farming the need for innovative, effective controls of farm nutrient losses in her council’s catchment was immediate.

The Rotorua district was already ahead of most others in dealing with nutrient losses and even in its goals to clean up waterways, she said.

Steve Chadwick 2

SETTING PACE: The Rotorua district is already ahead of most others in dealing with nutrient losses, Rotorua District Council Mayor Steve Chadwick says.

Lakes Rotorua and Rotoiti have been hailed recently as being at their cleanest in decades, after 2016 was set as the first goal for improvement.

Alum chemical dosing and channel diversion have helped achieve progress and their short-term effectiveness has been a driver to the region to try to establish longer-term solutions to nutrient losses off the region’s 560 pastoral farms.

Issues are likely to arise around alum toxicity through over-dosing, and an eventual breakdown of the Ohau diversion wall mean longer-term solutions are essential.

A memorandum of understanding was signed between community groups last year, representing a significant level of co-operation, Chadwick said.

Behind that sat a $40 million land-use incentive fund that was awaiting Cabinet approval and it was there innovative technological solutions would be rewarded, she said.

The fund would be available to land owners if they could prove they had new methods or technology at hand that would permanently alter nutrient losses on their properties.

The fund had expectations around it, including being granted only if it could be proved significant and permanent reductions in nutrient losses could be achieved, she said.

“We will not be paying for cost-neutral reductions. They must be long-term and innovative technology will be rewarded.”

Conference delegates were given insights into the significant reductions in nitrogen use that had been achieved on an efficient dairy unit in Southland.

The owner had undertaken a three-year proof of concept trial alongside DairyNZ benchmarking and demonstrated that a conventional dairy system could adopt a biological approach, maintain production levels, and reduce the amount of nitrogen used, while lifting production efficiency per kilogram of feed.

AgResearch scientist Dr Tanira Kingi, who chairs the lake quality stakeholder group in Rotorua, talked of the significant task that confronted researchers and farmers.

Farmers were expected to have farm nutrient plans filed by December next year that would remove 140 tonnes of nitrogen a year and another 100t of nitrogen a year by 2022.

“It may not sound a lot but it is a challenge in this catchment,” he said.

Chadwick reiterated the need for community involvement in the reductions, saying it was not just a rural problem.

“It is not just farmers. Townies also need to know how to better deal with waste water and nutrients.”

She acknowledged biological farming, with its assortment of organic and conventional approaches, was a reasonably new concept, but one that could help farmers adapt better to the challenges they faced.

“It will be interesting to see how you pull it all together.”

Chadwick also acknowledged a task that sat beyond farmers’ responsibility or innovation.

That was dealing with the district’s sewerage treatment system, which breaches the nutrient discharge consent that expires in 2021.

Work was under way to find an alternative solution to wastewater treatment, she said.

“We also as a council have to find around $20 million to deal with Tarawera’s sewerage system.”

Alongside farmers’ nutrient reductions the council will also remove gorse, which contributes 30t of nitrogen a year into the lakes.

Source: Farmers Weekly

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