Agricultural soil erosion is not contributing carbon dioxide to
the atmosphere, according to research published Friday in the
online edition of journal Science.
The study was carried out by an international team of
researchers from the University of California Davis, the Catholic
University of Leuven in Belgium and the University of Exeter in
Britain.
They found that erosion is equal to about 1.5 percent of annual
fossil-fuel carbon emissions worldwide.
Carbon emissions and other greenhouse gases are causing
worldwide concern because they trap heat in the Earth's atmosphere,
a major contributor to global climate change.
Earlier studies suggested a broad range of erosion effects, from
erosion equaling 10 percent of fossil-fuel emissions and up to an
equivalent of 13 percent.
The team readjusted previous estimates of the amount of carbon
emissions.
"Some academics have argued that soil erosion causes
considerable emissions of carbon, and others that erosion is
actually offsetting fossil-fuel emissions. Now, our research
clearly shows that neither of these is the case," said lead author
Kristof Van Oost of the Catholic University of Leuven.
In their study, the researchers found that erosion acts like a
conveyor belt, excavating subsoil, passing it through surface soils
and burying it in hollows downhill. During its journey, the soil
absorbs carbon from plant material; when the soil is buried, so is
the carbon. Erosion, therefore, creates what can be described as a
"sinking" of atmospheric carbon.
Still, the researchers said, erosion is a problem that must be
addressed, because it has a detrimental effect on agricultural
productivity and the surrounding environment.
(Xinhua News Agency October 27, 2007)
