%0 Conference Proceedings %D 1992 %T Effects of tallgrass prairie vegetation on the concentration and seasonality of nitrate\-nitrogen in soil water and streams %A Ramundo, R.A. %A Tate, C.M. %A Seastedt, T.R. %E Smith, D.A. %E Jacobs, C.A. %K tallgrass prairie %X

Inorganic nitrogen concentrations in tallgrass prairie soils and streams exhibit a sinusoidal seasonal pattern; nitrate levels are relatively high in winter and low in summer. The pattern is not observed in either rainfall or canopy drip (throughfall). Thus, the pattern is created by plant root-microbial interactions; when roots are not active, nitrates accumulate and can be leached from the soil. We used nitrogen fertilizer and herbicide in a factorial experiment to test the strength of root uptake activities on soil water nitrogen. Soil-water nitrate concentrations were 10 times higher when prairie roots were deactivated by application of a foliar herbicide. Ammonium nitrogen concentrations were unaffected. When fertilizer was added, nitrate levels of soil water beneath herbicide-treated vegetation were double that of untreated prairie. Mineralization of nitragen from herbicide-treated roots was not believed to be the source of the increased nitrate. These and previous studies at Konza Prairie emphasize the importance of plant cover in maintaining low nitrate concentrations of streams

%I University of Northern Iowa %P 9 -12 %G eng %M KNZ00375