Why does organic milk have a higher carbon footprint?
The Oxford English
Dictionary defines a carbon footprint as “the
total amount of greenhouse gases produced to directly and indirectly support
human activities, usually expressed in equivalent tons of carbon dioxide
(CO2).”
So why does organic milk have a higher
carbon footprint?
Lower yields.
It takes 80% more land to
produce one unit of milk than conventional production does. Whilst energy is
saved by the avoidance of synthetic fertiliser applications, this is actually
being offset by the significantly lower yields and greater mechanical field
inputs. These low yields create a negative environmental knock-on effect
because an organic dairy farm needs a larger area to produce less milk than a conventional
farm.
Higher on-farm energy consumption.
The energy consumption per
functional unit in the on-farm process is around 20% higher on an organic model
than it is on a conventional one.
On-farm primary energy use
in the organic system is 15.8% 5 higher than the conventional system, while
organic milk required 33.9% 6 more fuel per thousand litres of milk.
Furthermore, the organic
systems requires approximately a third more man hours than conventional
systems. The longer man hours include machinery hours and therefore creating a
greater consumption of fossil fuels, in the form of diesel and electricity,
increasing organic milk’s carbon footprint.
Synthetic vs Organic Fertilizer.
The organic system can
require the spreading of up to 20 tonnes/ha of manure, and the average
conventional farm applies around 1100 kg/ha of synthetic fertiliser That is
around 20 times the weight difference in transport and management every year.
This figure is staggering when you consider the difference in power and
machinery hours needed to load, transport and spread up to 20 t/ha of manure
compared to a meagre 1.1 t/ha of synthetic fertiliser, having implications on
fossil fuel consumption and the carbon footprint. Furthermore, in many cases
when an organic farm has insufficient solid manure from its own cows it is
actually forced to import organic manure from other organic farms.
Higher methane emissions.
Methane gas is twenty three
times more potent than carbon dioxide. It is estimated that cows in the UK
alone produce up to 500 litres, per cow, of methane every day, a figure so high
that they account for 3% of the UK’s total greenhouse gas emissions.
Organic milk’s methane
contribution is 18% higher than conventional milk. In the UK showed the figure
to be 70% methane in the organic system, compared to 52% on the conventional
system.
The reason for the higher production of Methane
is that organic cows eat more roughage, this takes to longer to digest than the
diet of an animal in an intensive system. Grass is rich in cellulose and other
tough components; symbiotic bacteria living in her gut help break down this tough
food. Unfortunately, these bacteria emit huge amount of methane while doing
this job. Since and organic cow needs
more time to digest, she produces more methane than a conventional cow.
Supplementary Organic Cattle Feed.
A commercial dairy cow
cannot exist solely on a grass fed diet. The additional protein requirements
for organic dairy cows create a large carbon footprint in themselves, as the
produce cannot be grown in temperate/cool climates. The standards set by the
UK’s organic bodies forbid the use of GMO feeds which would lower the amount of
carbon used. Something that is often
overlooked is that Soya meal, a key protein rich ingredient is sourced from
farms in Asia, South America and the US. These imports are fuelling slash and
burn techniques and further deforestation in areas of South America. This
shatters the food mile argument from much further down the supply chain, before
the manufacturing process of feeds begins and even before feed is synthesised
into milk. Whilst Soya meal is not present in all cattle feeds, the
environmental impact of long distance goods importation must not be
underestimated.
SOURCES:
Does the carbon footprint of organic milk production
negate its environmental benefits?
Henry J.W. Robertson Oxford
Brookes University
What's the environmental impact of milk?
Is Organic Milk Better for the
Environment ? Not Really …
Waste Transfer Station Permit
Google Maps Ranking
Have a look in to the new GWP* work done by Myles Allan. You article is well cited but flys in the face of common sense. The fuel use in spreading fert pales in to insignificance when you take in the energy needed to create synthetic fert. Also it is likely to be transported much greater distances. While farms do move muck around, as you have said, its bulk means its not really viable over long distances.
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