They say more economic analysis to support proposed in-stream bottom-line values is needed.
“The levels proposed in the plan would require significant reductions in nitrogen loss and aren’t flexible enough to recognise local context and ambition,” Fonterra sustainable dairying manager Mat Cullen, said.
“We think alternate values that are not solely based on nutrients could achieve similar outcomes.”
DairyNZ’s says the new ecosystem health nutrient thresholds are not scientifically robust and are unlikely to achieve improvements in waterway health sought by the community.
It estimates the in-stream levels will significantly affect 20% of dairy farms regarding nitrogen losses and 30% regarding phosphorus.
Southland, Canterbury and Waikato will be most affected and modelling suggests reductions in nitrogen loss of 25-80% will be required.
Federated Farmers water spokesman Chris Allan said the proposed nitrogen reduction targets of up to 80% mean farming will virtually cease in large parts of the country.
DairyNZ supports the need to manage nitrogen in priority catchments where the science linking nitrogen to impact is clear.
But it does not support thresholds based on nitrogen loss because there is insufficient information or systems to deliver immediate action.
Action should be targeted to the highest nitrogen-surplus farms in each catchment, DairyNZ said.
Fonterra wants to expand on its nitrogen-risk scorecard and management programme that has been running for seven years.
Farm data is collected electronically in most cases and the model generates risk levels for using nitrogen fertiliser, increasing the stocking rate, winter cropping and using irrigation.
Farmers then make informed choices from farm management options.
Fonterra suggests adding regulations based on purchased nitrogen surpluses, defined as nitrogen taken onto a farm through fertiliser and feed, minus nitrogen exported from the farm in products.
That is a measure of a farm’s efficiency of nitrogen conversion and not a one-size-fits-all threshold.
“This hybrid type approach will be more effective both in achieving the changes in on-farm practices while providing significant cost savings and reducing complexity of implementation.
“Our nitrogen-risk scorecard focuses more broadly on on-farm efficiencies, which has the added benefit of improving our farmers’ overall bottom line,” Cullen said.
“The scorecard clearly identifies on-farm practices that contribute to elevated nitrogen loss risk, which lets farmers take specific actions to improve.
“Unlike Overseer, this model also takes away some of the geographic factors outside a farmer’s control such as higher rainfall or leakier soil.”
Fonterra also opposes mandatory 5m riparian fencing setbacks where that forces farmers to relocate existing fences.
Farm Source director Richard Allen said common-sense dictates the focus should be on waterways that haven’t been fenced rather than penalising those farmers who voluntarily fenced years before it was mandated.
The identification of high-risk catchments is supported by Fonterra, along with interim controls on land use changes, national rules for winter grazing and mandatory farm environment plans.
DairyNZ suggests existing stock exclusion fences should be replaced at the end of the service life of the fence at whatever average setback is decided.
Intensive winter grazing rules should be based on those in the Southland Land and Water Plan – a permitted activity up to 15 degrees slope, maximum 15% of farm or 100ha.
DairyNZ opposes consented standards for stock-holding areas like feeding and wintering pads and said it is not clear whether calf sheds and wintering barns will be caught up in those requirements.