Thursday, May 19, 2022

SPECIAL REPORT | Southland farmers urged to improve water quality

The sooner farmers start addressing nutrient loss, the easier the transition and the less likely Environment Southland will need to implement punitive measures, chair Nicol Horrell says.

Environment Southland chair Nicol Horrell is urging dairy farmers to implement management changes that reduce nitrogen loss.

The NZ dairy herd increased 82% between 1990 and 2019, with some of the largest increases in Canterbury and Southland. Neal Wallace investigates the future of dairying in those regions and talks to some innovators who are confident that with the use of technology and management changes, dairying has a future.

The sooner farmers start addressing nutrient loss, the easier the transition and the less likely Environment Southland will need to implement punitive measures, chair Nicol Horrell says.

The council requires more action from farmers to improve water quality and to achieve that, ES is considering setting an extremely high bar.

“It is clear that just to meet national bottom lines for key contaminants, nitrogen and phosphorus, our region has to achieve significant reductions to the amount of contamination in our waterbodies,” says Horrell.

Final standards are still to be confirmed, but three nutrient reduction models are being circulated by ES: the NPS-FW; the ES proposed water and land plan; and Murihiku Southland freshwater objectives, which focuses on the health and wellbeing of water bodies.

“We have modelled three different sets of outcomes, so the three reductions represent different levels that might be required to achieve a specific outcome in our waterways.

“These objectives represent the level required to achieve hauora, or a healthy resilience in our waterways.”

ES calculates a 47% reduction in nitrogen is required to meet NPS-FW national bottom lines, but to achieve the council’s proposed water and land plan standard, the required reduction increases to 66%.

To meet the Murihiku Southland freshwater objectives, the reduction required is 70%.

Similarly for phosphorus, a 21% reduction will comply with national bottom line standards, but ES is considering a 69% target to comply with its land and water plan and 70% for provincial freshwater objectives.

For E.coli the council’s plan requires an 82% reduction, but 90% to meet freshwater standards. That standard will also require a 24% decline in suspended sediment in rivers and 32% decline for visual clarity.

According to the council’s proposed land and water plan, catchments such as Waituna require a reduction of 96% in total nitrogen (TN) and 62% in total phosphorus (TP), Mataura 79% and 58%, Aparima-Pourakino 64% and 34% and in Oreti-Invercargill 62% and 75%.

Over the whole province, the average reduction required by the council’s plan for both TN and TP is 70%.

Ivan Lines, a dairy adviser with Invercagill-based Agribusiness Consultants, said farmers acknowledge water quality must improve, but the proposed emission targets are idealistic and will return the provincial waterways to a pre-human state.

Lines warns that based on Overseer data, meeting those levels will make dairying and sheep farming, Southland’s largest industries, impossible as neither will be able to reduce emissions to ES’ levels.

“A sheep farm can’t achieve it, but trees might or we could revert the province to tussock, its natural state,” Lines said.

Human activity impacts the environment.

“ES says these limits can be achieved, but that have not said how to achieve that in practice or what the cost will be to achieve that,” he said.

He has seen DairyNZ studies that dispute ES analysis of periphyton levels and water quality, which he says the council analysis has been overstated.

He said technology and management techniques are currently available to achieve a 30-35% reduction in emissions, but 90% could be a struggle over the 25 years the land and water plan will be implemented.

“I think over time we should be able to get that to improve further, and most farmers are striving to achieve that already,” he said.

A deluge of large, scientific documents has made it difficult for land-users to understand let alone keep track of proposed changes. 

“I think the whole process ES has been going through has been pretty average to date,” he said.

“To get waterways back to their natural state in a human-modified environment will be incredibly hard to achieve.”

Given the size of the changes ES is requiring, Lines said it needed a more critical analysis than the council has given it.

A Regional Forum will recommend methods to achieve draft freshwater objectives which will only be formalised once ES considers recommendations and other information and formalises the plan change to the proposed Southland Water and Land Plan.

Horrell rejects claims ES standards will take Southland water back to a pre-human state and that the economic cost will decimate the Southland community.

“The economic impacts of the limit setting plan change will continue to be assessed as we move through the formal process.

“We have not yet made any decisions and we have more information to gather, including more information that combines science and economic modelling,” says Horrell.

He accepts the size of nutrient loss decline could be confronting, but the 25-year implementation timeframe and new technology such as nitrogen inhibitors, new nitrogen products or application methods will temper any impact.

He predicts a 20% decline in cow numbers in the province over the next 20 years, but says that decline will be driven by commercial factors rather than just the new regulations.

For example, the Southland Dairy Hub, an industry-funded research farm near Winton will be crucial in finding specific solutions to specific southern conditions, Horrell said.

The best way to get farmer buy-in is to provide a map, set interim targets and let industry decide the best way to get there, he said, which is what the council intends to do.

“I believe we need to put out ambitious but practical targets over 10 years,” Horrell said.

“The cumulative effect will be significant.”

No fan of the ability to grandparent nutrient losses, he said he favours a situation where two neighbouring farms have the same lower nutrient loss targets.

Dairying has expanded into some areas of Southland where soils are not suitable, and he said the market could enable that issue to take care of itself or it may require some persuasion, but that is not an issue the council has addressed.

The council’s water and land plan is before the Environment Court but Horrell said within the next year it will be matched to the Government’s National Policy Statement (NPS) on freshwater, which has to be implemented by 2025.

A 2019 nutrient loss study of 90 livestock, horticulture and arable farms reveals the vast majority of dairy farms were losing between 25kg and 55kg/ha/year of nitrogen and 0.5kg and 1.5 kg/ha/year of phosphorus.

Modelling of mitigation measures show nutrient losses can be reduced by between 10% and 40% within the existing farm production systems, but it did impact profitability.

“Some dairy farms had relatively high baseline nutrient losses for the industry and few mitigations,’’ an ES report states.

“For these farms to achieve relatively low nutrient losses, they will need to consider other options, such as retiring land or a change in farm production system.”

Farms with low nutrient losses had less ability to mitigate those losses. 

Read more articles in the special report series “Dairying has a future

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