
Read the
magazine
story to find out more. Portable
Rainfall Simulators Helping Fight RunoffBy Jan Suszkiw October 12, 2001With the pull of a cord, researchers
can now simulate thunderstorms on demand with portable showers that
allow for detailed studies of field conditions that promote phosphorus runoff
into lakes, reservoirs and other water bodies. This summer, 40 teams of scientists across the country used the portable
rainfall simulators (PRS) to help standardize their collection of soil and
runoff data in agricultural watershed regions. Until recently, such research
has primarily been confined to the laboratory and carried out by scientists
using different methods, notes Agricultural Research Service (ARS) soil scientist Andrew Sharpley. With rainfall simulators, its now possible to coordinate such efforts
and generate results for easier comparison, adds Sharpley, with ARS
Pasture Systems and
Watershed Management Research Laboratory, University Park, Pa. There, he
helps coordinate the National Phosphorus Research Project, an ARS-led effort
involving 21 ARS labs, 16 state universities, USDAs
Natural Resource Conservation Service,
and the Environmental Protection Agency. The projects main objectives include determining how much phosphorus
the soil can retain before losing the nutrient to runoff, creating a reliable
indexing system to assess and rank a farm sites vulnerability to
phosphorus runoff, and devising new guidelines by which farmers can maximize
their crop yields using manure and fertilizer while minimizing runoff. Driving the effort is concern over phosphorus enrichment of fresh water,
which can speed eutrophication, a natural aging process. One manifestation is
the growth of aquatic weeds and blue-green algae that can clog filters, crowd
out beneficial plants and deprive aquatic life of oxygen. At field sites, scientists can simulate how it all begins on 20-square-foot
plots by starting a gas-powered pump that forces water through the simulators'
plumbing systems and into nozzles that convert it to rain. The
plots are showered at a thunderstormlike rate of nearly three inches per hour.
Once puddling and runoff occur, metal borders downstream collect the water and
direct it to gutters that empty into plastic bottles for weighing and analysis.
A more detailed story in
Octobers
Agricultural Research magazine. ARS is the U.S. Department of
Agriculture's principal scientific research agency. U.S. Department of Agriculture |