The proposed plan change 2 comes as council policy makers work to align the nitrogen leaching limits with what is the eighth iteration of Overseer since the leaching limits were first calculated in 2007.
The latest version increases leaching limits by 60%.
Last year the council was told by the Environment Court it had to refuse consent to farmers unable to restrict nitrogen leaching to the totals laid out in the One Plan’s original Table 14.2 nitrogen leaching limits.
“The figures were tied to Overseer’s version 4.0,” council chairman Bruce Gordon said.
“We are now up to Version 6.3 and there is a need to have those figures recalibrated.”
The implications are for farmers in land use classes one and two to see their cumulative maximum leached nitrogen move to 45-51kg a hectare a year, up from 27-30kg/ha a year.
By year five that limit will have moved from the original table’s estimate of 25kg/ha a year allowable, to 40-46kg/ha a year.
Originally, most farmers in the region, also known as Horizons, couldn’t meet the original Table 14.2 figures, despite the plan intending to improve water quality within the means of most farmers.
Gordon said the changes will realign the plan’s leaching limits with the most up-to-date science but do not mean more nitrogen will be going into the region’s river systems.
Measurements taken by the council found some declines in nitrogen levels in waterways, with no increases approaching 60% that latest Overseer calculations estimate.
That indicates losses to the rivers are about the same but the amount converted to nitrous oxide gas is greater than originally estimated.
All information relating to the plan change will be with Environment Minister David Parker by November and Gordon expects it will be formally in place by early to mid-next year.
Once sorted, the next challenge will be Plan Change 3, and a key part of that will be to address the issue around market gardeners’ ability to meet nitrogen leaching limits and problems around Overseer being able to effectively measure those losses.
Many are leaching nitrogen at double the rate of some pastoral farmers and next year’s Plan Change 3 should give them formal consent to continue, subject to progressive reductions in nitrogen leaching levels over 20 years.
Federated Farmers Manawatu-Rangitikei president Richard Morrison said the plan change came after Horizons had been in a difficult position, and he hoped the change did not end up getting pushed back into court to re-litigate.
“What they have come up with is as good an option as we are likely to get.
“The original plan was pretty forward-thinking, to put nitrogen numbers into a table, but the science has moved on and that only reflected what was known at the time.”
Plan Change 3, signalled for next year, will bring even broader impacts on the region with the need to address issues around nitrogen losses from market gardens.
That in turn raises issues about how committed the region will remain to produce production.
