A 15% reduction in livestock numbers may be the only way to meet tough new methane targets being recommended by the Climate Change Commission as there is no silver bullet yet available.
Researchers are working on breeding, farm systems and feed technology and the impact of new nitrogen limits will help, but the consensus is it will be tough to meet the commission’s 15.9% reduction by 2035 without some lowering of stock numbers.
The commission claims that better feeding, breeding and land use change to horticulture, exotic and native forestry, will see farm livestock numbers fall 15% below 2018 levels by 2030, enabling biogenic methane targets to be met without new technology.
Commission chairman Rod Carr says under current trends methane emissions will fall short of the 10% reduction by 2030 set in the Zero Carbon Act.
His committee has set even more challenging targets and that by following their formula emissions could be 6.5% below 2018 levels by 2025, 11.4% by 2030 and 15.9% by 2035.
DairyNZ chief executive Tim Mackle is concerned the commission’s suggested target could become Government policy, warning if implemented it will reduce farm profitability by 17% and cause financial hardship to a third of dairy farmers.
Genetics and smart feeding projects by the Pastoral Greenhouse Gas Research Consortium, AgResearch and genetics companies could allow farmers to achieve lower greenhouse gas emissions without a similar loss of productivity.
Scientists have spent a decade identifying sheep that emit 11% less gas than their average flock mates without sacrificing their ability to produce quality meat, milk and wool.
Lead scientist Dr Suzanne Rowe from AgResearch says scientists are now at a point where they can predict by identifying gut bacteria which sheep will be high gas offenders and those that will be low.
Dr Rowe and her colleagues are now applying their understanding to cattle, aiming to screen dairy herds to find low methane gut profiles.
Dozens of high genetic worth bulls owned by Ambreed and LIC, capable of spreading tens of thousands of daughters through the population every year, offer significant potential for rapid deployment of low methane dairy genetics.
What is fed to those low emitting animals may enhance those genetics and some simple cropping solutions are offering encouraging results.
AgResearch forage scientist Arjan Jonker says a trial feeding sheep almost entirely rape and turnip crops can almost slice a third off emissions without compromising health.
“This is definitely proving to be a viable option but is still obviously at the research end of the spectrum,” he says.
Work on condensed tannin clovers is also looking promising with clovers contributing as much gas emissions as rye grasses.
Trials on smart grazing of existing tetraploid grasses are proving cow numbers can be cut with a proportionately greater increase in milk solids, with such grasses delivering both lower nitrogen losses and less gas emissions.
Companies like Barenbrug are now spending as much time educating farmers on how to make the most from such feed technology, as selling the seed itself.
The Farm Systems Change project run across 17 farms has also reinforced the value of doing simple things right, by focusing farmers on their herd’s health and feed regime.
Results show those following the system are 30% more efficient than average dairy farms, were making significantly more money, and carried less cows per hectare to achieve it.
Farmers methane reducing toolbox is unlikely to include genetic engineering despite positive AgResearch trials completed offshore with high sugar ryegrass.
The most promising prospect is Fonterra’s trials with nutrient company DSM, working on how to combine the methane reducing feed additive Bovaer into NZ dairy systems.
Bovaer has proven promising overseas, dropping methane emissions by 30%. The trick for researchers in NZ is how it responds and can be combined into a predominately grass based diet.
Fonterra also has several other closely guarded projects underway that show initial promise, but there are several criteria that have to meet.
“It has to be good for the planet, but also good for the farmer in that it is cost effective and practical,” says Fonterra’s chief science officer Dr Jeremy Hill.
“It also has to be good for the cow in terms of her performance and health, and finally it has to be good for the milk in terms of composition and residues.”
Since animal urine is the single greatest source of nitrogen in a pastoral system, reduced stock numbers will lower nitrogen inputs and, by default, methane emissions,
ECan rules require Canterbury farmers to gradually reduce nitrogen losses on average by 15% but up to 90% depending on catchment.
“I can’t say this amount of nitrogen loss will convert into stock numbers, but we don’t see an interface between climate mitigation and the nitrogen mitigation needed to meet nutrient loss,” says council planning and environment manager, Andrew Parish.
“No one wants to push farmers off their land.”
In an analysis of the Government’s Essential Freshwater national policy statement, Charlotte Irving from the AgriBusiness Group at Lincoln University, says a new bottom line for permitted nitrogen loss will require a 27% reduction on average across all New Zealand.
Economic modelling reveals that to achieve this across the Waikato catchment requires 160% increase in afforestation and a reduction in pastoral land use of 68% for drystock and 13% for dairy.
