Nitrogen retention capacity of a northern hardwood forest soil under ammonium sulfate additions
- Rutgers Univ., Piscataway, NJ (United States)
- SUNY College of Environmental Science and Forestry, Syracuse, NY (United States)
- Institute of Ecosystem Studies, Millbrook, NY (United States); and others
To determine the N-retaining capacity of a beech-dominated stand in the Hubbard Brook Experimental Forest, we added (NH{sub 4}){sub 2}SO{sub 4} at three levels (40, 160 and 520 kg N{center_dot}ha{sup {minus}1}{center_dot}yr{sup {minus}1}) to replicate plots in monthly increments for two years, and measured NH{sub 4}{sup +} and NO{sub 3}{sup {minus}} concentrations in monthly samples from zero-tension lysimeters. The two lower treatment levels failed to increase N loss through the deepest soils horizon when compared to controls. Plots under the highest treatment level retained >95% of the added N; NH{sub 4}{sup +} accounted for 77% of the leaching loss. The treatments caused an accumulation of exchangeable NH{sub 4}{sup +} in the soil, but concentrations of exchangeable NO{sub 3}{sup {minus}} remained small, even after samples were incubated at room temperature. Leaching, uptake by plants, and the increase exchangeable NH{sub 4}{sup +} accounted for 3-25% of the added N. Accumulation of available N without nitrification contradicts common expectations concerning N saturation. It was not clear why excess N was not nitrified. 74 refs., 4 figs., 4 tabs.
- Sponsoring Organization:
- USDOE
- OSTI ID:
- 96332
- Journal Information:
- Ecological Applications, Journal Name: Ecological Applications Journal Issue: 3 Vol. 5; ISSN 1051-0761; ISSN ECAPE7
- Country of Publication:
- United States
- Language:
- English
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