01974nas a2200145   4500008004100000245010400041210006900145300001300214490000700227520141000234653002201644100001901666700001601685856012701701       1988                        eng d00aFactors influencing nitrogen concentrations in soil and water in a North American tallgrass prairie0 aFactors influencing nitrogen concentrations in soil and water in  a725 -7290 v203 a<p>The influence of roots, soil fauna and microbes on nitrogen concentrations in soil water in annually-burned tallgrass prairie were evaluated using porous cup lysimeters and a series of manipulations involving an insecticide, clipping of the vegetation, and C and N additions to the soil surface. An organophosphate insecticide (isofenphos), which significantly reduced densities of certain nematode and arthropod groups, resulted in small but statistically significant declines in soil water NO3- concentrations during 2 of 3 yr of study. Organic N, the dominant form of soil water N, was unaffected by treatment. Clipping the foliage weekly during the spring resulted in significant reductions in annual foliage production, but failed to change concentrations of soil water NO3- or organic N. Nitrogen additions (10 g N m-2 as NH4NO3) greatly increased soil water NO3- concentrations; however, when 250 g C sucrose m-2 were concurrently added to plots, there was a significant reduction in soil water NO3- concentrations. Soil water NH4+ concentrations were unaffected by treatment. These studies emphasize the importance of microbes as the dominant factor affecting soil water N concentrations in carbon-rich soils. Plants, soil fauna and nitrogen fertilizers do affect N. dynamics, but, under annually-burned conditions in the tallgrass prairie, these effects are obscured by microbial processes</p>10atallgrass prairie1 aSeastedt, T.R.1 aHayes, D.C.  uhttp://knz.lternet.edu/content/factors-influencing-nitrogen-concentrations-soil-and-water-north-american-tallgrass-prairie