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| Titel |
Effects of biochar and elevated soil temperature on soil microbial activity and abundance in an agricultural system |
| VerfasserIn |
Chris Bamminger, Christian Poll, Sven Marhan |
| Konferenz |
EGU General Assembly 2014
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 16 (2014) |
| Datensatznummer |
250096374
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| Publikation (Nr.) |
 EGU/EGU2014-11874.pdf |
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| Zusammenfassung |
| As a consequence of Global Warming, rising surface temperatures will likely cause increased
soil temperatures. Soil warming has already been shown to, at least temporarily, increase
microbial activity and, therefore, the emissions of greenhouse gases like CO2 and N2O. This
underlines the need for methods to stabilize soil organic matter and to prevent further
boost of the greenhouse gas effect. Plant-derived biochar as a soil amendment could
be a valuable tool to capture CO2 from the atmosphere and sequestrate it in soil
on the long-term. During the process of pyrolysis, plant biomass is heated in an
oxygen-low atmosphere producing the highly stable solid matter biochar. Biochar is
generally stable against microbial degradation due to its chemical structure and
it, therefore, persists in soil for long periods. Previous experiments indicated that
biochar improves or changes several physical or chemical soil traits such as water
holding capacity, cation exchange capacity or soil structure, but also biotic properties
like microbial activity/abundance, greenhouse gas emissions and plant growth.
Changes in the soil microbial abundance and community composition alter their
metabolism, but likely also affect plant productivity. The interaction of biochar
addition and soil temperature increase on soil microbial properties and plant growth
was yet not investigated on the field scale. To investigate whether warming could
change biochar effects in soil, we conducted a field experiment attached to a soil
warming experiment on an agricultural experimental site near the University of
Hohenheim, already running since July 2008. The biochar field experiment was
set up as two-factorial randomized block design (n=4) with the factors biochar
amendment (0, 30 t ha-1) and soil temperature (ambient, elevated=ambient +2.5°C)
starting from August 2013. Each plot has a dimension of 1x1m and is equipped
with combined soil temperature and moisture sensors. Slow pyrolysis biochar from
the C4 plant Miscanthus was first put on top and then manually incorporated into
20-30 cm soil depth. Differences in the isotopic signature of the biochar and the soil
organic matter make it possible to trace the flow of biochar-derived carbon into
different labile C pools such as CO2 or microbial biomass. Spring barley litter of the
previous growing season was mixed into soil together with the biochar. Rapeseed
oil plants were sown one week after biochar application. Weekly gas sampling
between the crop rows allows the determination of CO2, N2O and CH4 fluxes. In
addition, 13CO2 will be measured at specific dates in order to calculate the proportion
of biochar-C in emitted CO2. First soil sampling after biochar application was in
November 2013 and soil was taken in three depths (0-5, 5-15 and 15-30 cm). After the
first three months we could not observe any effect of biochar on CO2 and N2O
emissions, but elevated soil temperature increased emissions of both gases. Data
on soil microbial abundance and community composition will be available soon. |
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