Professor Russell Death of Massey University laments the decision to put off setting the critical allowable nitrogen levels in waterways until at least next year. The Government has cited a lack of certainty around the science underpinning the numbers.
The initial proposals lowered the upper limit for acceptable dissolved inorganic nitrogen (DIN) levels to 1mg a litre of water.
“The science supports 1mg a litre upper maximum for ecosystem health but even that is too high.
“It is okay as a bottom line if we are willing to accept some degraded streams but for healthy waterway levels 0.6 to 0.8mg/litre is required.”
Delaying setting a limit means it will probably never happen.
Presently 95% of waterways already fall under 1mg/litre of nitrogen but a 1mg/litre bottom line along with other proposed nutrient bands would have prevented things getting worse.
“If there is no speed limit we will inevitably speed even if we know it is not safe.”
Death noted China has had nutrient limits similar to our proposed ones since 2012.
“Can we really say we have a clean, healthy environment if we are willing to accept nitrogen limits greater than those of China?”
He says the science around DIN levels is very convincing and most of the advisory group supports the 1mg/litre limit.
It is understood five of the 14 members were not convinced about the science supporting the 1mg/litre limit.
Death said the 190kg a hectare a year cap on synthetic nitrogen use is unlikely to have any significant effect given fertiliser is only a minor contributor to nitrogen losses compared to cow urine.
“It is a band aid that appears to be doing something but actually not.”
Government estimates put the cost of the reforms at $160 million a year, of which the farming and horticultural sector bears about $120m.
Death said there might be some short-term hardship for some farmers pushing the envelope on waterway impact.
“But I would prefer to see the Government protecting our clean, green image, which has already taken a hammering, to protect the future incomes for most farmers who want to do the right thing.”
He accepts the shift in riparian strips from a 5m set back to 3m is a sensible move.
“The science again shows the benefit of 5m over 3m is minimal while the cost to farmers is relatively high, especially if they have already fenced their streams. So, I am pleased about that. But fencing will not stop the nitrogen getting into waterways and that is currently our biggest issue.”
The extra moeny allocated for fencing is probably a waste, with most of the streams that need to be fenced already fenced.
“More fencing, particularly on sheep and beef farms, is not needed. Sheep and beef farmers need to focus on reducing sediment, in my opinion, and fencing is not always the best solution for that, particularly in erosion-prone high country.”
