Wai Kōkopu technical advisor Alison Dewes (right) at the Pongakawa on-farm agroforestry day.
Wai Kōkopu technical advisor Alison Dewes (right) at the Pongakawa on-farm agroforestry day.
Decreasing a herd and retiring challenging land has reduced greenhouse gas emissions by a third and made farms in the Pongakawa catchment more profitable long-term, farmers and rural leaders heard at a recent field day.
Farmers, bankers, scientists and foresters descended on the 329ha Ao Marama Farms property in Pongakawa for insights on the benefits of land use change to improve water quality and climate resilience.
Since 2021, milk solids per cow are up 17 per cent, imported feed is down 80 per cent and nitrogen applied per hectare was cut from 178 to 106kg/ha.
N losses are now down 46 per cent per kg/ha and average phosphorous loss is down 23 per cent per kg/ha.
Pivotal to the farmers’ own wellbeing, and that of their animals, was shifting to once-a-day milking and planting trees on slopes greater than 26 degrees (LUC class 6), which over two decades will provide carbon income.
They produce more milk and there’s less wastage since going once-a-day milking in 2019.
The Bay of Plenty Farm Forestry Association field day was organised by the Wai Kōkopu Society.
The society has planted 200,000 trees in the catchment, conducted 1200 water quality tests and checked and remediated 300 fish passages with the Bay of Plenty Regional Council.
Wai Kōkopu technical advisor Alison Dewes asked farmers to decide what fired them up most, as this was a good way to match them up with the right advisor and build a farm plan for their goals.
The society is seeking to retire another 40-50ha and plant another 100,000 trees next year.
She said farmers that retired erosion-prone slopes were more profitable longer term.
“By working with Ao Marama farm to retire the land over 6e - or greater than 26 degrees - in this case, this business is now 58 per cent more profitable in the long term with the carbon income.”
Reducing cow numbers allowed the financing for trees.
Dewes said because of the difficult country, the farm was only harvesting around half the pasture of the better land, and by retiring it, carbon income superseded grazing income per hectare on a 10-year analysis.
“Farms that are not too intensive, that are doing simple things like looking after their cows really well and putting animals at the heart of their business, reducing wastage and not overusing inputs or overusing fertiliser, are getting high production per cow from fewer cows and were found to be the most profitable with the lowest risk and the lowest footprint.
“If you start to intensify too far, you’ll find yourself on a treadmill. Your risk goes up, and you get more marginal returns which are riskier as milk price comes down and costs go up.”
For the Ao Marama farm plan, Wai Kōkupu did a land use capability survey and whole farm economic modelling of various scenarios for land use change, conducted by Phil Journeaux.
The catchment group fenced a riverside area at the end of the valley which was then planted in natives.
Some areas had been previously planted, harvested and replanted with radiata pine.
Farmers, bankers, scientists and foresters attended the Pongakawa on-farm agroforestry day.
The farm owners Ann Cameron and Will Nettleingham chose radiata pine, redwood and mixed natives to plant another 29ha, with natives supplied through Wai Kōkopu and the Bay of PlentyRegional Council.
The radiata pine cost $1600 per ha compared to $2484 per ha for the coast redwood.
Graham West, of Forest X, prepared the planting plan with participation in the ETS among the couples’ objectives.
He said radiata pine was the first choice, with redwoods, natives and poplar, nut trees and autumn tones added by the owners to improve biodiversity and add colour.
West, the national president of the NZ Farm Forestry Association, said pinus radiata held its value when seen beyond its timber harvest.
“Native forest advocates have attacked pine, but it’s created a whole forest industry in New Zealand because it grows everywhere rapidly with minimum management,” he said.
“Every part of it can be used and it’s had 70 years of genetic improvements.
“To me, it should be called the amazing pine.”
He said the East Coast should not have had radiata pine as the solution for its soil type and slopes.
However, the canopy of mature trees on slopes slowed the flow of water before it reached low-lying and riparian areas, which was important for intercepting water coming from overland flow.
“During the on-farm day, the Bay of Plenty Regional Council shared how 70 per cent of nutrients were coming from overland flow.
“The issue is how you slow down the rainfall when you get these intense events.
“It’s largely a tree canopy that will catch and slow rainfall down.
“The conversation should be around what functional requirements a landowner wants.
“Slowing rainfall, sequestering carbon and protecting the estuary from nutrients are achievable from forest planting, if done without any timber production requirement.”
He warned that radiata pine would not hold hillsides until they reached the age of 25 years when their root morphology had developed.
But work by Scion informed science about the root morphology of pinus radiatia, which can stand up for 100 years or 150 years, allowing understorey to grow.
Scion was learning more about pinus radiata through its Tree Root Microbiome Programme.
Lead scientist Dr Steve A Wakelin said the project would help people understand the role of plant microorganisms in the ecosystem.
“Whether this is plant disease, nutrition, carbon storage, biodiversity, or productivity - microbes have an important role to play.
“The Human Microbiome Project revealed how vitally important gut microbes and function are to human health. Now where the gut has gone, soil will follow.”
Radiata pine in New Zealand is an introduced species and now makes up 90 per cent of our planted forests.
Only a small proportion of the genetic material available was introduced when it arrived here.
Scion said these pine trees currently thrived in New Zealand soils, and understanding why was important to their long-term survival, especially in the face of climate change.
In March, Scion scientists visited the United States to collect soils from pinus radiata in California.
In collaboration with the Rúa laboratory at Wright State University in Ohio, the soil samples were processed and DNA extracted to identify what microbes make up the tree microbiome in sampled locations.
Soil samples were sent to collaborators at Woodwell Climate Research Centre to understand the differences in soil properties.
Sampling of soils from the roots of Pinus radiata in New Zealand got underway in early 2022.
Scion molecular ecologist and PhD candidate within the programme, Sarah Addison, said microbes co-evolved with pinus radiata roots, and they had always existed.
“Our challenge is that we just don’t know enough about them, and we need to change that.
“The microbiome represents a way for plants to expand their natural capabilities, using the microbes to adapt to changing environments more quickly than the plant alone can.
“This will allow trees to grow and thrive in conditions beyond their natural ranges, hopefully extending their survival in the face of climate change.”
Wai Kōkopu Society is in its final year of $4.3 million funding from MPI, MFE, Bay Trust and TECT to develop climate resilience and initiate carbon farming and lower footprint farming systems.
Another $3.2 million raised by the society from MFE was donated to the iwi collective Te Wahapu o Waihi. - Supplied content
