Return to HydroWeb HomepageISSN 1058-3912
Electronic journal of the International Association
for Environmental Hydrology
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JEH Volume 8 (2000), Paper 6, March 2000 Posted
March 11, 2000
USE OF ISOTOPICALLY LABELED FERTILIZER TO TRACE NITROGEN FERTILIZER
CONTRIBUTIONS TO SURFACE, SOIL, AND GROUND WATER
Donald H. Wilkison
Dale W. Blevins
U.S. Geological Survey, Independence, Missouri, U.S.A.
Steven R. Silva
U.S. Geological Survey, Menlo Park, California, U.S.A.
ABSTRACT
The fate and transport of a single N fertilizer application through
plants, soil, runoff, and the unsaturated and saturated zones was determined
for four years at a field site under continuous corn (Zea mays L.) management.
Claypan soils, which underlie the site, were hypothesized to restrict the
movement of agrichemicals from the soil surface to ground water. However,
N fertilizer moved rapidly through preferential flow paths in the soil
and into the underlying glacial till aquifer. Most N transport occurred
during the fall and winter when crops were not available to use excess
N. Forty months after application, 33 percent of the fertilizer had been
removed by grain harvests, 30 percent had been transpired to the atmosphere,
and 33 percent had migrated to ground water. Although runoff volumes were
50 percent greater than infiltration, less than 2 percent of the fertilizer
was lost to runoff. Small measured denitrification rates and large measured
dissolved oxygen concentrations in ground water favor the long-term stability
of NO3-1 in ground water. Successive fertilizer applications,
in areas that lack the ability to moderate N concentrations through consumptive
N reactions, risk the potential of N-saturated ecosystems.
Reference: Wilkison, D.H., D.W. Blevins and S.R. Silva; Use
of Isotopically Labeled Fertilizer to Trace Nitrogen Fertilizer Contributions
to Surface, Soil, and Ground Water, Journal of Environmental Hydrology,
Vol. 8, Paper 6, March 2000.
Donald H. Wilkison
U.S. Geological Survey
301 W. Lexington
Independence, MO 64050
U.S.A.
E-mail: wilkison@usgs.gov