AFTER planting 100,000 trees on their New England grazing property “Blaxland” since 1990 – and still planting – the Street family expected to be well in the black on greenhouse gas accounting.
But “Blaxland” is not in the black.
Despite carbon sequestration by trees, it is still 872 tonnes of carbon dioxide equivalents per year (CO2-e/y) in the red, according to a life-cycle analysis overseen by CSIRO.
The finding surprised the Streets, who are genuinely interested in playing their part in mitigating climate change.
If agriculture is included in the Carbon Pollution Reduction Scheme (CPRS) under current Kyoto accounting rules, the family says “Blaxland’s” emissions bill, if unsubsidised, would force them to reconsider their farming future even at a modest carbon price of $20 a tonne.
“If we wanted to be carbon neutral, we would have to plant about half the property out to trees,” said Jim Street, who runs the 871-hectare farm in partnership with wife, Caroline, and son, Charlie, between Uralla and Walcha.
That’s not an appealing idea to Charlie Street, who is taking on more of the farm’s management and wants to remain “foremost a producer of food and fibre”.
The Streets decided to have a carbon audit done on “Blaxland” in the comfortable expectation the property would be sequestering more carbon than it emitted.
All their trees met Kyoto compliance, in that they were hand-planted since 1990. The property currently carries 33 hectares of corridor and block plantings of mostly native species, plus 13 ha of “engineered woodlands”.
The woodlands are an experimental design, in which two rows of trees are planted at wide intervals across the whole paddock, and left unfenced to lower costs.
The paddock is locked up for about 18 months, until the trees can withstand grazing, but then grazed freely.
The trees provide carbon sequestration of 237t of CO2-e/y, according to a study conducted by CSIRO scientist, Dr Sandra Eady, in conjunction with Southern New England Landcare and the Northern Inland Forestry Investment Group.
That goes nowhere near addressing the 1109t of CO2-e produced by “Blaxland’s” livestock enterprises.
The farm’s greenhouse gas emissions come mainly from 5500 to 6000 Merinos producing a 17.5-micron wool clip.
Sheep were estimated to produce an average of about 927t of CO2-e/y, 718t in the form of enteric methane and the remainder from dung and urine, or through fertiliser and indirect emissions.
The Streets’ cattle trading enterprise, which turns over about 120 head every 12 months, was estimated to deliver 177t/CO2-e/y.
About 160t came from enteric methane, and the remainder was attributed to dung, fertiliser and indirect emissions.
The report noted that the “carbon intensity” of the sheep enterprise was higher than that of the cattle enterprise: 1.35t CO2-e per hectare for sheep compared with 1.22t CO2-e/ha for cattle.
While the sheep flock is self-replacing, much of the greenhouse gas overhead for bought-in store cattle remained with the property that bred the stock.
The findings brought the Streets to the rapid conclusion that the rules needed to alter drastically from the Kyoto provisions, or the Australian livestock industries would be annihilated.
This week’s news that agriculture may not have to participate in the CPRS still left a lot of questions unanswered, Jim Street said.
“We need to have a better understanding of how farms can use their natural assets in a meaningful way for mitigation.
“We really need to take a closer look at how we can do it through grass and soil – that’s far more in keeping with our farming system.”
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