HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Johnson, D. W. Articles by Todd, D. E. Search for Related Content PubMed Articles by Johnson, D. W. Articles by Todd, D. E. Agricola Articles by Johnson, D. W. Articles by Todd, D. E.

Nitrogen Mineralization, Immobilization, and Nitrification Following Urea Fertilization of a Forest Soil Under Field and Laboratory Conditions¹

ABSTRACT

Following a 200-kg urea-N/ha fertilization in a loblolly pine stand (Pinus taeda), soil mineral N levels (almost entirely NH₄⁺) declined from 200 ppm 20 days after fertilization to < 10 ppm within 161 days. Similar patterns had been previously observed following urea fertilization in a Douglas-fir stand. After the decline in soil mineral N, 20% (40 ppm) of fertilizer N was mineralized within 4 weeks of aerobic incubation in the laboratory at 25°C. Nitrogen mineralization in control soils did not occur after 7 weeks incubation.

In contrast to field results, urea additions to control soils in the laboratory resulted in rapid net N mineralization. The difference between laboratory and field fertilization results is thought to be due principally to differences in available C supplies, i.e., large (> 2 mm) litter and roots were excluded from laboratory tests.

The maximum rate of nitrification during incubation was related to the supply of NH₄⁺ substrate, whereas the delay period was probably related to the initial populations of nitrifiers.

Additions of 100 kg P/ha as triple superphosphate in the field and equivalent additions of NaH₂PO₄ in the laboratory had little or no effect on results.

¹ Support for the senior author was provided by a Eugene P. Wigner Fellowship at Oak Ridge National Lab. Analytical funds were provided by the Div. of Distributed Technology, U. S. Dep. of Energy, under contract W-7405-eng-26 with Union Carbide Corp. Pub. no. 1465, Environmental Sciences Division, ORNL.

² Research Associate, Research Associate, and Senior Technician, respectively. Oak Ridge National Lab., P.O. Box X, Oak Ridge, TN 37883.

Received for publication June 7, 1979. Accepted for publication December 14, 1979.

This article has been cited by other articles:

				C. Ringrose and W. A. Neilsen Growth Responses of Pinus radiata and Soil Changes following Periodic Fertilization Soil Sci. Soc. Am. J., September 29, 2005; 69(6): 1799 - 1805. [Abstract] [Full Text] [PDF]

				D. W. Johnson, P. S. J. Verburg, and J. A. Arnone SOIL EXTRACTION, ION EXCHANGE RESIN, AND ION EXCHANGE MEMBRANE MEASURES OF SOIL MINERAL NITROGEN DURING INCUBATION OF A TALLGRASS PRAIRIE SOIL Soil Sci. Soc. Am. J., January 1, 2005; 69(1): 260 - 265. [Abstract] [Full Text] [PDF]