| In a bad slug year, some no-till
farmers plow to decrease the infestation. "Knowing this, we wanted to see
how much carbon loss one plowing might cause," Owens says. He concluded
from that study that a one-time plowing did not cause great losses of carbon in
the soil profile.
The Coshocton work is part of a longstanding national research effort by ARS
to solve problems like this oneand others. ARS does the research in
response to needs identified by USDA's Natural Resources Conservation Service,
which works directly with farmers to reduce soil erosion through voluntary
A 2000 survey done by the Conservation Technology Information Center in West
Lafayette, Indiana, showed that conservation tillage is used on 37 percent of
U.S. planted acres. The practice is responsible for U.S. farmland storing more
carbon than it loses.
Carbon Loss From Erosion or Leaching
In a second study related to plowing and carbon losses, Owens and colleagues
checked the effects of tillage on the amount of carbon lost with soil in
erosive runoff. They found that different tillage practices make no difference
in the concentrations of soil carbon attached to eroding soil particles. But
tillage still causes more carbon to be lost by water erosion than no-till does,
simply because erosion losses are higher and each particle of soil carries more
"This tells us that farmers who want to conserve carbon should choose a
practice with a focus on how erosive it is, rather than on how much carbon it
leaves in the soil," Owens says.
The third Coshocton study measured the effects of chisel-plowing and grazing
on carbon losses in soil water as it leaches down to groundwater. That route
has rarely been studied. Owens was able to confirm that the loss is as small as
suspectedaveraging 3 to 5 pounds of carbon a year from each of these two
diverse farming practices.
"Knowing where significant carbon losses occur helps farmers focus on
those areas," he says. "Our experiments show that plowing every year
will cause significant soil carbon losses over time, but that leaching is not a
significant route for carbon losses. We've also shown that farmers can plow
once without causing significant soil carbon losses. But they need to be aware
that this tillage benefit is heavily offset by increased soil loss and
decreased soil health and quality.
"Basically, we've found that farmers don't have to consider the effects
on carbon when they choose a tillage method," says Owens. "They just
have to choose the least erosive method that will solve their problem and have
the best long-term soil benefit. We hope that these findings will encourage
more farmers to return to no-till corn."By
Agricultural Research Service Information Staff.
This research is part of Soil Resource Management, an ARS National
Program (#202) described on the World Wide Web at
Lloyd B. Owens is in
the USDA-ARS North
Appalachian Experimental Watershed Unit, State Rte. 621, P.O. Box 488,
Coshocton, OH 43812; phone (740) 545-6349, fax (740) 545-5125.
"To Plow or Not To Plow?" was published in the
issue of Agricultural Research magazine.