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)
