story to find out more.
Hills on the Skogstad
family farm in western Minnesota have light-colored hilltops where topsoil has
eroded and darker low spots where soil has been deposited.
The Hills Are Sagging By Don Comis
December 8, 2005
The pallid color of the North American prairies' rolling landscape is
a tell-tale sign of soil erosion. The hilltop knobs have lighter-colored soil
and less lush, green wheat than do the hill bottoms. This was long thought to
be the result of dry soil only.
Researchers at the Agricultural Research Service (ARS)
Central Soil Conservation Laboratory in Morris, Minn., studied one such
wheat field and found that gravity and erosion from annual plowing also have a
great deal to do with the pallid soil. After more than 40 years of annual
plowing, tillage erosion moved more than 27 tons of soil an acre a year in some
spots, with water erosion moving another 9 tons an acre. The light spots are
where topsoil moved down the hill, exposing shallow subsoil whitened by
Wheat yields on the knob were at most half of those on the rest of the
field, with the highest yields on hill bottoms.
ARS soil scientists
Papiernik and Mike Linstrom, now retired but working as a collaborator, are
doing this research with scientists at South
Dakota State University and the University of Manitoba in Canada.
Tillage and gravity erode soil the most under conditions such as these
knobs, where there is a change from a relatively flat hilltop to a steep slope.
Topsoil accumulates near the bottom of the hill where the steep slope becomes
relatively flat land.
This also points to the possibility that using earth-moving equipment
to move topsoil back up the hill-as several are farmers are doing-could
increase yields enough to justify the expense.
For a follow-up study, Papiernik and colleagues are investigating the
economic and environmental effects.
about the research in the December 2005 issue of Agricultural Research
ARS is the U.S. Department of
Agriculture's chief scientific research agency.