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Relieving substrate limitation-soil moisture and temperature determine gross N transformation rates

Author:
  • Per Bengtson
  • Ursula Falkengren-Grerup
  • Göran Bengtsson
Publishing year: 2005
Language: English
Pages: 81-90
Publication/Series: Oikos
Volume: 111
Issue: 1
Document type: Journal article
Publisher: Wiley-Blackwell

Abstract english

A field experiment was designed with the objective to reveal the interactions between soil moisture, temperature, total, dissolved, and phosphate buffer extractable C and N, and microbial activity in the control of in situ gross N mineralization and immobilization rates in a deciduous forest. We had three alternative hypotheses to explain variations of the gross N transformations: 1) microorganisms are C limited, 2) microorganisms are N limited, or 3) neither C nor N limit the microorganisms but moisture and temperature conditions. Each hypothesis had specific criteria to be fulfilled for its acceptance. The results demonstrated that gross N transformation rates were more dependent on and variable with soil moisture and temperature than the size of the different C and N pools. The immobilization of N was dependent on the gross mineralization rate, suggesting that the production of enzymes for mineralization of organic N and the immobilization of N from the surrounding soil is disconfirmed when the intracellular N content of the microorganisms is sufficiently high. If the microorganisms are starved for N, enzyme systems involved in both the assimilation and mineralization of N are activated. The mean in situ gross N mineralization rate was two orders of magnitude higher than the natural N deposition in the area and the N addition in the NITREX experiments, meaning that a reduction in the gross N mineralization rate of about 1% would be enough to compensate for the addition of inorganic N. This decrease would hardly be detectable given the great spatial and temporal variability of N transformation rates.

Keywords

  • Biological Sciences
  • Ecology

Other

Published
  • Microbial Ecology
  • ISSN: 1600-0706
Per Bengtson
E-mail: per [dot] bengtson [at] biol [dot] lu [dot] se

Researcher

MEMEG

+46 46 222 37 60

E-F212

Sölvegatan 37, Lund

50

Research group

Microbial Ecology

Projects

Doctoral students and postdocs

PhD students, main supervisor

 

PhD students, assistant supervisor

Jian Li

Experimental setup