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The use of soil to reduce carbon dioxide in the atmosphere

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As we saw in the last lecture, a major cause
of climate change is the rapid rise in the

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level of carbon dioxide in the atmosphere
over the last century.

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If we could reduce the amount of CO2, perhaps
the rate of climate change could also be slowed

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down.

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One potential method involves enhancing the
role of the soil that plants grow in, with

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regard to absorbing CO2.

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Rattan Lal, a soil scientist from Ohio State
University, in the USA, claims that the world's

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agricultural soils could potentially absorb
13 per cent of the carbon dioxide in the atmosphere

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- the equivalent of the amount released in
the last 30 years.

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And research is going on into how this might
be achieved.

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Lal first came to the idea that soil might
be valuable in this way not through an interest

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in climate change, but rather out of concern
for the land itself and the people dependent

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on it.

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Carbon-rich soil is dark, crumbly and fertile,
and retains some water.

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But erosion can occur if soil is [question1]dry.
which is a likely effect if it contains inadequate

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amounts of carbon.

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Erosion is of course bad for people trying
to grow crops or breed animals on that terrain.

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In the 1970s

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and '80s.

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Lal was studying soils in Africa so devoid
of organic matter that the around had become

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extremely [question2]hard, like cement.

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There he met a pioneer in the study of global
warming, who suggested that carbon from the

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soil had moved into the atmosphere.

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This is now looking increasingly likely.

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Let me explain.

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For millions of years, carbon dioxide levels
in the atmosphere have been regulated, in

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part, by a natural partnership between plants
and microbes - tiny organisms in

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the soil.

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Plants absorb CO2 from the air and transform
it into [question3]sugars and other carbon-based

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substances.

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While a proportion of these carbon products
remain in the plant, some transfer from the

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[question4]roots to fungi and soil microbes,
which store the carbon in the soil.

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The invention of agriculture some 10,000 years
ago disrupted these ancient soil-building

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processes and led to the loss of carbon from
the soil.

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When humans started draining the natural topsoil,
and ploughing it up for planting, they exposed

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the buried carbon to oxygen.

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This created carbon dioxide and released it
into the air.

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And in some places, grazing by domesticated
animals has removed all vegetation, releasing

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carbon into the air.

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Tons of carbon have been stripped from the
world’s soils - where it’s needed - and

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pumped into the atmosphere.

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So what can be done?

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Researchers are now coming up with evidence
that even modest changes to farming can significantly

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help to reduce the amount of carbon in the
atmosphere.

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Some growers have already started using an
approach known as regenerative agriculture.

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This aims to boost the fertility of soil and
keep it [question5]moist through established

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practices.

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These

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include keeping fields planted all year round,
and increasing the [question6]variety of plants

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being grown.

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Strategies like these can significantly increase
the amount of carbon stored in the soil, so

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agricultural researchers are now building
a case for their use in combating climate

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change.

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One American investigation into the potential
for storing C02 on agricultural lands is taking

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place in California.

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Soil scientist Whendee Silver of the University
of California, Berkeley, is

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conducting a first-of-its-kind study on a
large [question7]cattle farm in the state.

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She and her students are testing the effects
on carbon storage of the compost that is created

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from waste - both

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agricultural, including manure and cornstalks,
and waste produced in [question8]gardens,

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such as leaves, branches, and lawn trimmings.

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In Australia, soil ecologist Christine Jones
is testing another promising soil-enrichment

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strategy.

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Jones and 12 farmers are working to build
up soil carbon by cultivating [question9]grasses

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that stay green all year round.

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Like composting, the approach has already
been proved experimentally; Jones now hopes

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to show that it can be applied on working
farms and that the resulting carbon capture

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can be accurately measured.

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It’s hoped in the future that projects such
as these will demonstrate the role that farmers

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and other land managers can play in reducing
the harmful effects of greenhouse gases.

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For example, in countries like the United
States, where most farming operations use

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large applications of fertiliser, changing
such long-standing habits will require a change

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of system.

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Rattan Lal argues that farmers should receive
[question10]payment not just for the corn

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or beef they produce, but also for the carbon
they can store in their soil.

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Another study being carried out ...