
Topsoil: Keeping It FreshBy Don Comis February 26, 1999Stockpiled soil--and its wealth of plant-helping fungi--will get stale if
"left on the shelf" too long, according to an
Agricultural Research Service scientist
in Wyoming. The finding could boost the odds for reclaiming strip mines on western
rangeland. It may also help explain why lawns, shrubs and gardens planted in
yards of new homes may not thrive if they're planted in near-sterile subsoil
instead of topsoil brimming with earthworms, helpful microorganisms and organic
matter. Federal and often state laws require mine companies to reestablish native
vegetation. But they typically salvage and store the original topsoil several
years before putting it back. Plus, digging, piling, spreading and compacting
soil destroys its water-holding pores. This lowers the odds that sagebrush and
other range vegetation can struggle through a drought. Native vegetation is so needy that topsoil removed from a site should be
returned within a few months or even respread on another site right away, if
possible, according to soil scientist Gerald E. Schuman at ARS' Rangeland
Resources Research Unit in Cheyenne, Wyo. In a greenhouse study, Schuman and University
of Wyoming colleague Peter Stahl found that mycorrhizae--beneficial
root-dwelling fungi--will die in topsoil stored too long. But the living
fungi's hairlike filaments can funnel water and nutrients to roots. In fresh and sterile batches of soil from a northeastern Wyoming coal mine
site, the scientists planted seeds of Wyoming big sagebrush. In fresh,
fungi-rich topsoil, seedlings survived 3 to 5 days longer after the soil dried
out. Those few days might be a crucial bridge allowing plants to survive until
the next rain. ARS is the U.S. Department of
Agriculture's chief scientific agency. A story about the research appears
in the February issue of the agency's Agricultural Research magazine
and on the World Wide Web at: http://www.ars.usda.gov/is/AR/archive/feb99/tops0299.htm Scientific contact: Gerald E.
Schuman, ARS Rangeland Resources Research Unit, Cheyenne, WY; phone (307)
772-2433, fax (307) 637-6124, [email protected]. Story contacts Rangeland Resources Research U.S. Department of Agriculture | |