ARS | Publication request: MODELING NITROGEN TRANSFORMATIONS DURING A LONG-TERM INCUBATION

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: May 23, 2005
Publication Date: June 15, 2005
Citation: Clapp, C.E., Molina, J., Lee, D.T., Layese, M.F., Miller, M.A., Hayes, M., Palazzo, A.J., Baker, J.M. 2005. Modeling nitrogen transformations during a long-term incubation [abstract]. EMSI/North Central NOM Workshop. p. 54.

Technical Abstract: Inorganic and organic N were determined on a Waukegan silt loam soil for a 90-wk aerobic incubation experiment. 15N labeled soil samples were taken from 2 different tillage treatments, till (T) or no-till (NT), and 2 residue management practices, returned (R) or harvested (NR). Triplicate samples of 4 treatment combinations (TR, NTR, TNR, and NTNR) were incubated in polyethylene bags (15 x 40 cm), 500 g each, at 35oC under constant water conditions. The initial NO3-N concentration for TR and NTR treatments were 30 to 70 mg L-1 higher than the TNR and NTNR treatments (10 mg L-1). At week 90, the values had risen to 425, 550, 150, and 180 mg L-1 NO3-N, respectively, with slight increases still occurring. Inorganic N concentration was determined at periodic intervals after KCl extraction. Extracted samples were converted into NH4-N by the Mason jar diffusion technique, for analyses of total N and 15N. Atom-% 15N (inorganic) increased than reached a plateau. The extent of each phase depended on the treatment. This information was used to estimate the 15N content in the organic pools of the model NCSOIL.