An article written by Brian Barth from Modern Farmer magazine, that talks about the benefits of low carbon farming and soil carbon sequestration.
This article comes from Modern Farmer and was written by
Brian Barth who comes from the U.S. To
read the article in its original format please click here.
Carbon farming. The phrase is suddenly on the lips of every
major player in the sustainable food movement.
Michael Polan deemed it agriculture’s “secret weapon” in a
December op-ed for the Washington Post . Bill McKibben, in his praise for an upcoming book on the topic described
carbon farming as “a powerful vision” one that he hopes will “promote major
changes in our species’ use of the land.” Paul Hawken went so far as to call it
“the foundation of the future of civilisation” with potential to surpass the
productivity of industrial agriculture. “
Why all the hubbub? And, for that matter, what exactly is it
Carbon farming is agriculture’s answer to climate change.
Simply put the goal is to take excess carbon out of the atmosphere, where the
element causes global warming and store it in the soil, where carbon aids the
growth of plants. The principle is
pretty straightforward – the practice, not so much.
Most folks understand that burning fossil fuels puts carbon
that was once buried deep beneath the earth into the atmosphere, turning the
planet into one big greenhouse in the process.
But in addition to petroleum underground, the soil on the surface of the
earth contains a sizable store of carbon in the form of organic matter – the stuff
that environmentally aware farmers and gardeners are all striving to
maximise. Plants add organic matter to
the soil when they decompose and photosynthesis, by definition, removes carbon
dioxide from the air and pumps it through the roots of plants and into the
Concern over climate change may have thrust the concept of
carbon farming into the limelight – 25 countries pledged to pursue it during
the December climate talks in Paris, but rangers like Gabe Brown who raises
livestock and an array of crops on 5,000 acres outside Bismarck, North Dakota,
have preached its virtues for decades. “All
soil biology eats carbon, and that’s how nutrients cycle,” explains Brown of
the network of microbes and fungi and earthworms underground. “Farmers ned to
think of carbon as their fertiliser, because it’s what drives a healthy system.”
At first glance, most carbon-farming techniques mirror age –
old organic growing methods: instead of relying on chemicals and pulverizing
the soil with constant tillage, you enrich it with compost and rotate a diverse
array of food and cover crops through the fields each season. But Brown and
other practitioners of carbon farming – Virginia’s Joel Salatin and Zimbabwe’s
Allan Savory are the best known among them – go to extraordinary lengths to
keep carbon producing organic matter in the soil and out of the atmosphere.
Ploughing is avoided like the plague. Instead of turning up the earth at the
end of a given crop cycle, Brown sends his livestock – Angus carrel, Katahdin
sheep, pigs and chickens – into the field to trample and eat the crop. He then uses a seed drill to plant the next
crop among the decaying roots of the previous one.
Brown, a former conventional commodity – crop farmer, still
grows corn, but with a groundcover of clover or vetch beneath the stalks. HE
follows each cash crop with a mix of pearl millet, Sudan grass, cowpeas,
sunflowers and other soil –enriching cover crops, combining up to 70 different
species in a single planting, Each occupies a slightly different niche in terms
of height, root depth, leaf shape, and growth rate, forming a dense blanket of
vegetation that pumps carbon from the sky to the soil and provides a rich “cocktail”
on which his livestock graze.
Brown says that he has greatly increased his profitability
since adopting carbon –farming practices more than 20 years ago. In addition to
improved yields on the corn, soy, and wheat he’s always sold on the wholesale
market, he now supplies beef, pork, eggs, broilers and honey to local customers.
Another way carbon farming pays off, at least abroad, carbon
credit markets. For the past five years, Australia’s agricultural sector has
benefitted from a nationally mandated cap and trade programme that lets farmers
who adopt carbon sequestration practices sell carbon credits to heavily
polluting corporations in need of offsetting carbon footprints. And two years ago, the World Bank established
a fund to buy carbon credits from Kenyan Farmers as a means to incentivise
climate-friendly practices in a part of the world known for its slash and burn
approach to the land.
America has yet to institute a federally mandated
carbon-credit system though nine northeastern and mid – Atlantic states have
adopted cap and trade schemes covering the emissions of 168 power plants. Only
California can claim a wide – reaching cap and trade program that requires more
than 600 polluters across various industries to offset their emissions but even
there, most farm-based practices for carbon sequestration remain ineligible for
credits. Under California’s current system, credits are available mainly to
farmers who are themselves big polluters – livestock farmers who install
anaerobic digesters to capture methane.
That’s starting to change thanks in part of the efforts of a
group of dairy farmers in Marin County. The challenge involves quantifying the
amount of carbon sequestered and providing assurance that the numbers can be
reliably replicated, according to John Wick co-founder of the Marin Carbon
project . Last year Wick’s organisation, in
conjunction with ecologists at the University of California, Berkeley – managed
to convince the agency that administers the stat’s voluntary carbon –credit exchange
(as opposed to its government mandated one) to grant credits to farmers who
spread compost over grazed grasslands. “We’re at that pivotal moment”, Wick
says, “between demonstrating scale, which we’ve done and implementation.”
Many consider livestock on pastureland the ideal system for
sequestering carbon. Each time an animal nibbles on a blade of grass, the roots
release a bit of carbon into the soil; pasture raised beasts and birds also
convert grass into marketable products like meat, dairy and eggs. But opponents
argue that animals emit as much carbon as they help sequester, pointing to the
belches and manure of ruminant animals as a major source of greenhouse gases.
Eric Toensmeier, author of the Carbon Farming Solution, the
new book that has Hawken, McKibben and other activists buzzing – offers a
reality check and a realistic solution. “There’s this conversation happening
that suggests grazing is the only way to go, yet the rates (of sequestration)
are among the lowest of all carbon-farming practices,” he explains. “Its quite
complicated when you really drill down into it.”
A proponent of long-lived perennials as the best carbon
capture, Toensmeier urges ranchers to consider silvopasture, the practice of
grazing livestock among trees, spaced widely to allow enough sunlight to reach
the fields as compensation for the carbon released by the animals. Yet he
acknowledges the many variables that influence a farmer’s decision making
process: “It’s a matter of what practices are suited to your climate and fit in
your marketing mix, as well as the mechanisms for financing the transition.”
The U.S Department of Agriculture is helping farmers
transition to carbon sequestering practices with a free web-based tool called COMET-Farm,
which provides an approximate carbon footprint based on user – supplied data
and allows farmers to experiment with different land management scenarios to
see which works best. USDA air-quality scientist Adam Chambers says that the
data the tool provides should help pave the way for famers to monetize
sequestration practices as the carbon market matures. “This is the cookbook, if
you will, for how farmers can accomplish emissions reductions,” he explains.
Through a partnership with the USDA, Chevrolet recently
purchased 40,000 carbon credits from 23 ranchers in North Dakota who have
voluntarily pledged to adopt no-till methods on their combined 11,000 acres of
grazing land. Chambers hopes the transaction which equates to taking 5,000 cars
off the road and is the largest of its kind to date in the US will jump – start
the market for farm – based carbon sequestration. As one of the world’s largest
auto – companies, it’s fitting that Chevy should start that ball rolling.
Five Tenets of Carbon Sequestration
No – till: Tilling mixes soil with air, allowing carbon to
oxidize back into the atmosphere. Instead, focus on perennial crops that don’t require
tillage, or use a no-till seed drill for large scale annual plantings.
Organic mulch: cover the soil around small-scale plantings
with a wood chip or straw mulch to prevent carbon losses. On large plantings,
leave crop residue in place as mulch. As it decomposes, the residue fuels the
carbon cycle in the soil.
Compost: Compost is rich in a stable (not easily oxidized)
form of carbon. Carbon farmers recommend dusting it over the surface of the soil
– you can spread it directly over the grass in your pasture – rather than
tilling it in.
Livestock rotation: Moving concentrated herds and flocks of
animals through a series of small paddocks on a regular basis is preferable to
letting the animals forage continuously over a single large area. Many carbon
farmers move their animals every day and try and let each paddock “rest” as
long as possible between grazings.
Cover Crops: Fast growing species such as clover and vetch
keep the soil covered and enriched with carbon through the winter and may also
be planted together with cash crops during the growing season to compensate for
carbon lost when those crops are harvested.