| July 29, 2005,
ARS News Service: Carbon stored in soil during
the first five years of bermudagrass management was two
to three times greater when the grass was grazed than
when it was harvested for hay or left unharvested, according
to Agricultural Research Service (ARS) scientists.
Carbon dioxide in air is important for life on earth,
but its rapidly rising concentration is cause for concern,
because of its contribution to the greenhouse effect
and potential global warming. Maintaining more carbon
in soil means less of it escapes into the atmosphere.
Ecologist Alan Franzluebbers and animal scientist John
Stuedemann of ARS found that cattle grazing on forage
grasses could help improve carbon storage in soil. In
studies at ARS' J. Phil Campbell, Sr. Natural Resource
Conservation Center in Watkinsville, Ga., they found
that adding cattle grazing to a crop rotation system
can be beneficial by enriching the soil with carbon
and other nutrients. Also, income could be generated
from the cattle.
In Georgia, plowing and other practices have resulted
in lost top soil. Fortunately, permanent pasture now
accounts for about 18 percent of land area in the southeastern
states, compared to 20 percent for cropland. Converting
land to permanent pasture has significantly reduced
soil erosion.
In most instances, crop farming and cattle farming
are separate operations. Franzluebbers and Stuedemann
envision a system where calves could be raised on pasture
in rotation with other crops like corn or wheat. The
type of crop would determine when grazing would occur.
According to the researchers, putting as little as
10 percent of existing cropland in rotation with grazing
could significantly reduce costs, due to lower inputs
such as herbicides, and generate additional income from
the livestock. The next step for the researchers is
looking at long term integration of annual crops with
perennial grasses.
ARS is the U.S. Department of Agriculture's chief scientific
research agency. |
