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B.Marschnerand A.Bredow
Effects of Sterilization and Incubation Temperature
4.6
Effects of Sterilization and
Incubation Temperature on
Formation and Quality of
Dissolved Organic Matter in
Soils
B. M
ARSCHNER
1
AND
A. B
REDOW
2
1
Ruhr-UniversitätBochum,GeographischesInstitut,
Universitätsstrasse150, D-44780 Bochum; and
2
Technische
UniversitätBerlin,InstitutfürÖkologie, FGBodenkunde,Salzufer
11-12, D-10587 Berlin, Germany
Introduction
Dissolved organic matter (DOM) in soils can contribute to a number
of important soil processes. These include the solubilization and
complexation or sorption of metals and hydrophobic organic compounds
which may thus affect plant nutrition, soil genesis or the bioavailability,
toxicity and translocation of pollutants (Zsolnay, 1996). Furthermore,
pedogenic DOM can act as substrate for microorganisms in the soil
solution or in groundwater, enabling denitrification or other redox-relevant
activities which influence solution chemistry (Qualls and Haines, 1992;
Møller
et al
., 1999).
Still, little is known about the processes that are involved in the
formation of DOM or about the relevance of these processes to DOM
quality. Generally, litter leachates, root exudates and microbial degradation
products are regarded as important DOM sources (Zsolnay, 1996).
However, drying-rewetting cycles, temperature and changes in solution
chemistry also affect DOM release (Powlson and Jenkinson, 1976;
Tipping and Woof, 1990; Gödde
et al
., 1996; Lundquist
et al
., 1999).
This may occur either directly through physical or chemical processes
or indirectly through the stimulation or inhibition of microbial activity.
Our aim was therefore to investigate the role of microorganisms in
the release or formation of DOM and on some of its ecologically
relevant properties in response to different temperatures and incubation
periods. In order to exclude microbial activity, soils were exposed to
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