Pongakawa dairy farmers Ann and Will Nettleingham have swapped out cows for trees in the past two years and provide an inspiring example of a pathway to mixed land use that ensures their farm remains viable and environmentally sustainable.
The couple opened up their property to 80 farmers, foresters and growers to visit as part of their participation in the Wai Kōkopu catchment group, covering 35,000 hectares of land behind the heavily polluted Little Waihi Estuary, near Maketu.
The catchment is one of the most environmentally challenged in New Zealand, requiring a 70% reduction in nitrogen and 40% drop in phosphate losses, with E coli also a major problem in waterways.
After years of consolidating land titles, increasing cow numbers, and using nitrogen to fill feed holes, Ann Nettleingham said, the farm peaked as a high-pressure unit, milking 750 cows twice a day across the entire 250ha, which includes steep, 30-degree-plus slopes.
“It was high pressure for a lot of the time, on the cows, the people and the environment.”
A forced move to once-a-day milking five years ago helped bring a more holistic, relaxed pace to the operation, and the move to plant more trees and cut herd numbers has taken it a step further.
In the past two years cow numbers have been cut back from 750 to 440, and under a 2022 planting programme, pine, redwood and mixed natives were planted, totalling 30ha and taking the total planted area to 67ha.
The plantings are dominated by carbon-generating pines, comprising about half the planted area, along with redwoods and 8ha of planted natives alongside 18ha of existing native trees.
“With the forestry, we have been dropping our cow numbers from that peak of 700 down to 456, basically reinvesting the money from those cows back into the trees,” Ann said.
The couple have also identified 38ha of land suitable for kiwifruit development, to occur when returns improve in the near future.
The couple’s inspiration for their transition came in part from Wai Kōkopu founding member John Burke’s enthusiasm and proven track record of native planting on his own award-winning farm.
Input from expert forester Graham West also helped determine the most effective way to plant the pines to ensure they are efficient at slowing surface water flow, while continuing to grow grass in the valleys for the cows.
Contour planting, as opposed to running lines of pine straight from ridge to valley, will also lend a greater aesthetic to the trees as they mature.
West said putting the trees into the Emissions Trading Scheme to get carbon-averaged cashflow also makes the move easier. If government meddling in the scheme were less, there would be more farmers inclined to embark on a transition like the Nettlinghams’, he said.
“There will be no environmental benefit for four years from the pines, but in that time they will grow like mushrooms, and by year six will be slowing 40% of rainfall runoff.”
West acknowledged many landowners may be “anti-pine”, but at $1600 a hectare planting cost they remain the most cost-effective, rapid-growing solution to sequester carbon and improve water slope runoff.
“They have this amazing ability to grow almost anywhere on any slope in NZ. Scientists are only just starting to understand why this is and how its root system enables it.”
West dismissed claims pines would collapse after 30 years, pointing to stands in Kaingaroa Forest that have existed for 100 years, and other long-lived stands in Wellington city.
The economics of the move for the Nettlinghams also look positive.
Modelling by agricultural economist Phil Journeaux highlighted how per-cow production has increased by 22% from the original farm operation. Total earnings are up 33%, and greenhouse gases emissions are down by a third, as are nitrogen losses.
Based on those numbers, catchment group operations manager Alison Dewes challenged farmers to reconsider whether putting stock on steeper country was in fact the right move.