Friday, September 17, 2010

Expert witnesses: knowledge not required

The ignorant have a right to be heard in public enquiries about soil carbon. The evidence is there in the Report of the Inquiry into Soil Carbon Sequestration in Victoria.
“…a number of experts and key agencies advised the Committee that the inquiry had encouraged them to think through many of the issues associated with soil carbon sequestration, and articulate a position on the prospects for soil carbon sequestration, for the very first time.” No wonder so much of the opinion parading as expert comment is half-baked and worthless. For example: “A report commissioned for Dairy Australia and submitted by Gipps Dairy as part of its submission to the inquiry suggested that soil carbon sequestration on dairy pastures will be hard to achieve because of the difficulty of increasing pasture production without decreasing stocking rates.” Nonsense. This claptrap deserves a place on the list of The Most Stupid Things Ever Said About Soil Carbon, alongside the Bucket Theory and The Cost of Growing Humus. Gipps Dairy sets up a pea and thimble trick when it claims that there can be three separate potential uses for one tonne of pasture produced on a dairy farm and that an estimate of the economic value of each of those uses can be made.
The inevitable conclusion: “even at a carbon price of $250 per tonne of carbon dioxide equivalent, it is
more profitable to use one tonne of pasture to feed cows to produce milk than it is to retain the
pasture on the soil and let it decompose for the purposes of sequestering soil carbon.”
Soil carbon is not a zero-sum game. You don’t grow it by taking animals off pasture and letting it rot. The action of the animals – incorporating the uneaten grasses and manure – stimulates the microbial life, including the photosynthetic bacteria which do not depend on getting a bucket of organic matter for their growth. That is how carbon is made, and piling on the urea is how it is unmade.

Gipps data:
Table 6.1 Value of different potential uses for one tonne of pasture
Potential uses for pasture Value of uses of pasture
Produce hay bales $150
Feed cows to produce milk $260
Retain on soil and let decompose in order
to sequester soil carbon*
$21 at a carbon price of $25 per tonne of carbon dioxide equivalent
$206 at a carbon price of $250 per tonne of carbon dioxide equivalent
* This assumes that one tonne of pasture (dry weight) contains 45 per cent carbon, of which 50 per cent decomposes to create 0.23 tonnes of soil carbon. One tonne of soil carbon = 3.67 tonnes of carbon dioxide equivalent. The submission from Gipps Dairy also noted that the cost of fertiliser to produce one tonne of carbon has to be taken into account when calculating the costs and benefits of the scenarios outlined in the table.

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